Biology: Marine Biology
Biology: Marine Biology
Marine biology, the study of organisms that live in the ocean, incorporates aspects of many different disciplines, including physiology, biochemistry, molecular biology, microbiology, embryology, evolution, ecology, and organismal biology. Marine biology includes the study of microorganisms such as bacteria, protozoans, and fungi, as well as plants and animals, and all types of marine environments: coastal settings such as rocky shorelines, coral reefs, and beaches as well as the open ocean, the deep ocean, and ocean sediments. (This is distinct from biological oceanography, which studies the ocean and the ways that biological organisms influence its processes; many scientists working with the two fields address both perspectives, however.)
Marine biology has existed ever since humans foraged in the ocean for food, but in the last part of the twentieth century public awareness of the important role that marine organisms play in the global economy and climate has increased dramatically.
Historical Background and Scientific Foundations
The earliest marine biologists were people who found food in the ocean. Discarded shells of marine invertebrates often clutter sites inhabited by ancient coastal inhabitants. These people probably had a basic understanding of the behavior of the marine organisms they hunted and the way changing ocean current patterns influenced their abundance and diversity.
Early biologists were referred to as naturalists, or people who studied nature. Much early work is traced to Aristotle (384–322 BC), who was the first person known to make systematic observations of marine organisms.
In the eighteenth century Carl Linnaeus (1707–1778; also known as Carolus Linnaeus or Carl Linné) and later Georges Cuvier (1769–1832) developed the modern binomial naming and classification systems still in use today.
The field of marine biology began in the early 1800s, when naturalists first became involved in ocean research. Often considered the founder of marine biology, British naturalist Edward Forbes (1815–1854) collected marine animals in the Aegean Sea and compared his findings with those of Aristotle. Forbes's maps of geographic distributions of various marine species and study of the natural history of the oceans surrounding Europe introduced the scientific community to the ocean.
In 1859 Charles Darwin (1809–1882) published the theory of evolution he formulated during his voyage on the HMS Beagle. Darwin was a serious marine biologist, devoting a significant portion of his life to classifying barnacles and developing a theory of coral reef formation.
In the late 1800s oceanographic expeditions produced enormous amounts of information about marine organisms. In 1872 the British government financed a four-year circumnavigation of the globe aboard the HMS Challenger to describe marine species collected at all depths in all oceans. This voyage gave scientists their first glimpse of the enormous diversity of ocean life: The Challenger findings filled 50 volumes. Other expeditions followed, including the Blake expedition in the Caribbean and Gulf of Mexico, the Monegasque Princess Alice I and II, the German Valdivia expedition to study planktonic (floating) organisms, and the Norwegian Michael Sars expedition, which explored the North Atlantic.
Research institutions were established to analyze the results of these expeditions. The Marine Biological Laboratories were established at Woods Hole, Cape Cod, in 1888. The Scripps Institute of Oceanography at San Diego and Friday Harbor Laboratories on Puget Sound followed in 1903; all three remain important research institutions today. Around the same time numerous institutions were created in Europe such as the Italian Stazione Zoologica de Napoli (1872), the Plymouth Marine Laboratory in England (1888), and the Oceanographic Museum and Aquarium in Monaco (1910). Today, marine biology studies flourish at numerous institutions throughout the world, and dozens of scientific journals are dedicated solely to publishing such research.
Military technology played a major role in oceanic exploration during the first part of the twentieth century. The development of submarines during World War I led to the development of manned submersible craft, remotely operated vehicles, and scuba diving to explore the deep realms of the ocean. In 1960 a navy submersible called Trieste made the deepest manned descent ever made into the Mariana Trench in the Pacific Ocean. Seventeen years later, the submersible Alvin discovered organisms living around deep-sea hot vents. The need for improved communications and navigational information led to the development of sonar systems, satellite remote ocean sensing, and deep-sea drilling techniques, all of which have improved marine biology research.
During the second half of the twentieth century the field grew with the boom in technological advancement. The use of DNA markers to identify relationships between organisms, for example, is regularly used to evaluate fish stocks, determine evolutionary relationships among species, and understand how the physiological characters of individuals vary. Satellite remote sensing is used to track tuna and shark migration throughout the Pacific and understand how phytoplankton respond to climatic changes.
Prior to the mid-twentieth century, many marine organisms were only known to researchers, fishermen, and naturalists. Sea life was a limited concept to the average beachcomber. Following World War II, however, two events heightened the awareness of marine biology in the public mind: the explorations and masterful storytelling of Jacques Cousteau (1910–1987) and the campaign to save the whales.
Cousteau began his career as a French naval officer. With engineer Emile Gagnan, he developed the Aqua-Lung underwater breathing system, which eventually became the SCUBA (self-contained underwater breathing apparatus) diving apparatus. Cousteau also developed the SP-350, also known as the “diving saucer” or soucoupe, a submersible vehicle for deep-water exploration.
Cousteau produced and starred in award-winning films that documented marine life throughout the world and wrote best-selling books describing his ocean adventures. He produced The Undersea World of Jacques Cousteau television specials, which ran for nearly a decade and were nominated for numerous awards. Cousteau's explorations and his documentation of the places he went brought this exotic and exciting world into the living rooms of people unfamiliar with marine environments. Cousteau's ability to simplify scientific concepts for the public became known as divulgationisme, now a major influence on most modern TV documentaries.
In 1944 the International Whaling Commission was established to slow the slaughter of whales around the world. Financial pressure from whaling countries impeded the IWC's ability to prevent hunting, which led to a continuous of decline in whale populations. During the 1970s the environmental organization Greenpeace took action against whaling vessels by physically placing small boats between whalers and their quarry. These actions brought significant media attention to whales, their biology, and their life history, and this captured the public's imagination.
Such events introduced the public to the realm of the ocean and the organisms that live in it. For the United States in particular, where a large majority of the population does not live near an ocean, these events drew attention to the importance of the marine environment and the organisms that live within it.
Although Forbes contributed an enormous amount to the early scientific theory about the ocean, he also proposed one major incorrect hypothesis that influenced decades of scientific thought about distribution of life in the ocean. Forbes had served as a naturalist aboard the H.M.S. Beacon in 1841; researchers aboard the ship towed nets through the water at different depths, then analyzed their contents. This showed that fewer species and fewer organisms were collected from nets at deeper depths. As a result, Forbes proposed one of the first testable hypotheses about the distribution of life in the sea: that no life existed below 300 fathoms, or 1,800 feet (549 m), in the ocean. This theory became known as the azoic theory.
Azoic theory sparked considerable debate during the nineteenth century, and numerous voyages were undertaken specifically to test it. In 1850 Norwegian explorer and naturalist Michael Sars described 19 species that he collected below 300 fathoms, firmly disproving the azoic theory. Sars's work was further supported by collection of marine organisms from deep in the ocean on a later cruise aboard the HMS Lighting that studied the seas north of Britain. Additional proof that organisms lived in the deep ocean emerged when a transcontinental telegraph cable raised from the ocean floor 6,600 feet (2,012 m) below the surface was found encrusted with marine life.
Curiously, even though azoic theory has been refuted for more than 150 years, it is still mentioned in a historical context in many textbooks and articles about the history of marine biology. Its lingering impact suggests that the deep ocean resonates in the human psyche as a place of great desolation and mystery.
Marine biology is a broad field that applies nearly every component of general biology to marine organisms. Given the interdisciplinary nature of the field, marine biologists often borrow analytical tools from other biological disciplines. Large research groupings within marine biology include ecology, evolution, genetics, biochemistry, physiology, biomechanics, biotechnology, and biomedicine. These fields are not all-inclusive, but just represent some of the more active branches of marine biology.
Marine ecology deals with the interactions of marine organisms within their environment. Marine ecologists often focus their interest on a single environment within the ocean, such as the ocean floor (or benthos), the deep ocean, pelagic or open waters, as well as any of the various coastal environments, including the rocky intertidal zone, coral reefs, sandy beaches, and estuaries. Further, marine ecologists often study a specific region, defined by its characteristic climate or latitude. For example, marine ecologists studying the ice edge in Antarctica may encounter a similar ecosystem as marine ecologists studying the Arctic. On the other hand, a marine biologist studying giant kelp off the California coast will likely encounter very different ecology.
Marine ecologists also study how an organism survives within an environment, including how it eats, maintains homeostasis (a stable internal environment), and reproduces. They want to understand how organisms interact and how these interactions affect the survival of different populations. For a marine biologist studying the phytoplankton in the Southern Ocean near Antarctica, this might include learning how phytoplankton withstand freezing temperatures or avoid predation by krill. For a marine ecologist studying the Great Barrier Reef near Australia, research might involve the symbiosis between a clown fish and a sea anemone or what caused the numbers of the highly predatory crown-of-thorns starfish to explode.
IN CONTEXT: MODERN NATURALISTS IN OCEAN ENVIRONMENTS
Although the heyday of natural science is widely considered to have ended with the great technological advances of the late twentieth century, the ocean remains a place where much has yet to be discovered. As the threat to biological diversity in terrestrial ecosystems becomes more pronounced, marine biologists have begun to try to catalog the species that live in the ocean.
In 2007 researchers from the Smithsonian Tropical Research Institute participated in an effort to evaluate the abundance of species in the eastern tropical Pacific off the coast of Panama. Although they expected to discover some new creatures, nearly half the species they encountered had never previously been described scientifically. One scientist who specialized in ribbon worms found that 50% of the specimens he collected were new species. The relatively well-studied group of soft corals yielded 15 new species.
Between 2000 and 2010, more than 2,000 scientists from all over the world will collaborate on the Census of Marine Life, a project undertaken to analyze the amazing variety of life in the ocean. One of the project's initial efforts studied a heavily fished region, the Gulf of Maine. While biologists expected to collect approximately 2,000 marine species from this region, they registered instead more than 3,300. Most were microscopic phytoplankton, accounting for one-fifth of the species collected.
While the majority of new species discovered are small and difficult to collect, even very large species are still being discovered in the ocean. On February 22, 2007, fisherman in the Antarctic landed a colossal squid, a species that had previously only been known from two tentacles discovered in the belly of a sperm whale in 1925. This squid was brought aboard a fishing vessel nearly intact. Scientists were able to estimate that fully grown a male of this species could attain a size of 45.5 feet (14 m), even longer than a sperm whale.
Questions about the origin of species in different marine environments and evolutionary relationships between them form the basis for the study of marine evolution and genetics. For example, geneticists studying populations of the striped bass Brevoortia tyrannus have found differences in the mitochondrial DNA of fish from the Gulf of Mexico and the Atlantic coast of the United States. Such differences can help explain evolutionary change in response to changes in local environments.
Biochemistry and physiology explore the basic physical functions of marine organisms. A marine biochemist may try to isolate the chemical responsible for preventing ice formation in phytoplankton living in brine tubes in Antarctica's ice sheets. A marine physiologist may try to determine how the metabolism of a tropical clam and a closely related clam that lives near a deep ocean hot vent differ.
Biomechanics is a field of marine biology in which scientists study how the unique properties of living in a viscous world influence an organism's form and function. Questions investigated in this field include how the shape of a flat fish generates lift or how a worm living in a tube hollowed out from sediments on the bottom of the ocean generates a flow of water that removes waste and brings in food particles or how the shape of sea anemone changes in response to varying current speed. Results from this field have influenced modern design of cars, boats, and airplanes.
Marine biotechnology is the use of any marine biological system, organism, or organismal derivative to solve a technological problem, including fisheries biology and mariculture—fields that study the best way to harvest and farm marine organisms as food products. Fisheries biology involves understanding the population structure and reproductive behavior of marine organisms including small fish such as menhaden, sardines, and anchovies, as well as large predators like swordfish, salmon, and tuna. It also attempts to understand and manage stocks of invertebrate fisheries such as shrimp, lobster, crab, oyster, mussels, and clams.
As the wild populations of marine species began to decrease in the second part of the twentieth century, mariculture developed in response. Mariculture seeks methods of growing consumable marine organisms and plants for the commercial market. This requires balancing the physiological and ecological needs of the organisms with the economic interests of investors and the environmental concerns of watchdog groups and government agencies.
Marine biotechnology also focuses on developing products that can be used to solve industrial problems. Anti-fouling research is a large area of research in biotechnology. The growth of sessile organisms such as barnacles, mussels, and encrusting corals on underwater surfaces is a bane to many marine industries. In particular, fouling of ships hulls significantly decreases fuel efficiency, and removal of encrusting organisms is difficult and expensive. Research into natural anti-fouling chemicals resulted in the discovery of a potent anti-fouling agent in the soft coral Junceella juncea, which inhibits the growth of barnacles. This extract is incorporated into paints and applied to underwater surfaces. Other significant contributions include light-producing photo-proteins, used in numerous biochemical analyses, that were originally isolated from light-producing cells of jellyfish, as well as the development of insect repellents and sun blocks from chemicals found in marine organisms.
Arguably a subfield of marine biotechnology, albeit a very large one, marine biomedicine uses marine organisms as models of human systems, resulting in significant medical advances. For example, in 1967 biologist Graham Hoyle recognized that the barnacle Balanus nubilus contained the largest muscle fibers in the animal kingdom. He developed a system, subsequently used by researchers around the world, to use these fibers as a model of how human muscle cells, including the human heart, function. In 2005 researchers showed that a group of anticancer drug called bryostatins may slow Alzheimer's disease. The model that they used for their research was the marine snail, Hermissenda, which was well suited to the research because it has relatively simple neural networks, but yet the networks function in a manner similar to humans. Primary locations for this type of research include the Marine Biological Laboratories and Friday Harbor Laboratories.
Impact on Science
Just as marine biology draws heavily on many other subject areas, it also contributes to growth within those fields. Zoology often turns to marine biology to understand general features of animals. For example, two researchers at Friday Harbor Laboratories, Ken Lohmann and Dennis Willos, studied how magnetic fields affected the sea slug Tritonia diomedea. Slugs placed in tanks with active magnetic fields running across them always oriented themselves eastward. When the magnetic field is cancelled, the slugs orient themselves randomly. The researchers discovered that a neuron in the slugs responds to changes in the magnetic field. This could help explain the behavior of animals from fruit flies to sharks that seem to navigate using Earth's magnetic field. It could also represent the discovery of an entirely new animal sense.
The field of medicine has profited enormously from research on marine organisms, which often serve as simplified models of more complex human systems. For example, the sea urchin has been used to study fertilization and has led to important discoveries associated with understanding human birth defects. Studying the retina of the skate, a relative of the shark, has led to advances in understanding degenerative eye disease in humans. Sea squirts are studied to understand how diseases like HIV are transmitted.
Study of the long-finned squid (Loligo pealei) provided an enormous amount of information about human neurobiology and physiology. Mammalian nervous systems are made up of extremely small and delicate cells called neurons, which are difficult to study. Because the squid relies on very quick movement to avoid predators, squid have evolved a giant neuron that controls the movement of their mantle (outer body covering). This neuron is nearly 100 times larger than a mammalian neuron, almost 4 inches long. Since the 1930s, researchers have used squid neuron to understand how nerves function, the various protein signals involved with nervous function, and the properties of the fluids both inside and outside of the nerve cell. Understanding how squid nerve cells work has provided important information into how human kidney cells regulate the pH of the body, what effects the permeability of the membranes of the colon, and how blood flow to the brain is regulated.
Impact on Society
Marine biology has affected almost every aspect of society, from politics to economics to people's diet. In the American Northwest, water withdrawal for private or public use has diverted enormous quantities of water from streams that salmon and steelhead trout use as breeding grounds. These fish are anadromous, living the first part of their lives in the ocean then migrating to fresh water to live out their adult lives. This has stirred up an enormous debate over the relative value of the environment, water rights, and the economic value of the fisheries.
During the 1970s the environmental movement heightened public awareness of marine ecosystems to encourage the passage of laws to protect the environment. The Marine Mammal Protection Act of 1972 and the Endangered Species Act of 1973 both give priority to the protection of marine species over development by either government or industry. Internationally, CITES, the Convention for International Trade in Endangered Species, enacted in 1975, put in place similar protection for endangered species. The International Whaling Commission (IWC) has particular jurisdiction over the protection of whales and other marine mammals.
A significant part of the 1972 Clean Water Act covers both salt and fresh waters. In response to serious environmental pollution problems at Love Canal in upstate New York, Congress enacted the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), also called the Superfund Act, to fund environmental cleanup in areas that are heavily polluted. One of the best known Superfund sites is in Santa Monica Bay, near Los Angeles, where DDT, PCBs, and toxic metals were dumped in large quantities. Studies of the area showed significant changes in species composition, with a marked decrease in species diversity in the most polluted regions.
Pollution in marine environments has affected numerous fisheries, putting significant economic pressure on the industry as a whole. Pollution by the carcinogenic pesticide kepone in the Chesapeake Bay closed the crab fishery in the 1960s. The entire striped bass fishery was closed by PCB pollution. Mercury is one of the best known pollutants affecting marine organisms, causing severe neurological damage in large concentrations. Other heavy metals like lead and cadmium are serious marine pollutants as well. In certain places heavy metals can be found in significant quantities in many fish that are top predators, like swordfish and tuna.
IN CONTEXT: MARINE BIOLOGY AND MEDICINE: THE CONTRIBUTION OF THE HORSESHOE CRAB
An ancient marine relative of the spider, the horseshoe crab (Limulus polyphemus) has made major contributions to both medicine and the medical industry. These animals are large arthropods—approximately 2 feet (0.6 m) in length and weighing up to 10 pounds (4.5 kg)—that are very common along the East Coast of the United States. The animals are covered in a dome-shaped black carapace resembling a helmet. They also have a long telson or tail spike. Horseshoe crabs have very large compound eyes and a large optic nerve that connects the eye to the brain. This makes the horseshoe crab an ideal model for studying vision. In addition, the horseshoe crab's circulatory system and blood has been studied intensively because of its important antibiotic properties.
In the early 1930s, Haldan Keffer Hartline (1903–1983) used the horseshoe crab eye to study the way that the brain interprets visual signals. He discovered the visual process known as lateral inhibition, which is not only used in invertebrate visual systems, but is extremely important in human vision. Lateral inhibition is a mechanism that allows animals to improve the contrast along borders, thus improving the ability to discriminate between two objects. Hartline's discovery of lateral inhibition earned him the 1967 Nobel Prize for medicine.
Fred Bang (1916–1981), a researcher at the Marine Biological Laboratory in Wood's Hole Massachusetts, noticed that one of the horseshoe crabs he was studying had developed a fatal infection from a gram-negative bacterium. This infection caused the horseshoe crab's blood to coagulate into a gel-like substance. Working with hematologist Jack Levin at Johns Hopkins University, the team identified a blood component called a hemocyte. When a hemocyte comes in contact with a bacterial endotoxin, it releases a substance containing coagulogen that quickly congeals the blood into a semisolid mass.
Endotoxins are toxic and sometimes fatal to humans, as well. All surgical tools, tubing, drugs, intravenous products and blood products must be free of endotoxins before they are safe to use medically. Based on the properties of horseshoe crab coagulogen, a test called the limulus amoebocyte lysate (LAL) assay has been developed to determine whether endotoxins are present in a substance before administering it medically. In order to obtain coagulogen, blood is removed from the hemocoel of a horseshoe crab, and the animal can be returned, unharmed, to the ocean within 24 hours. A multimillion dollar industry has resulted from harvesting the blood from horseshoe crabs for this assay.
Even as the effects of pollution threaten the quality of seafood, people in the United States have begun to eat more of it. In 2001 the annual per capita consumption of fish and shellfish was 14.8 pounds, according to the National Oceanic and Atmospheric Association (NOAA); by 2005 it had increased to 16.2 pounds, an increase of 9%. As wild fish stocks decrease, mariculture has grown in response to consumer demand. Shrimp farming, in particular, has made great strides in developing sustainable farming practices that do not degrade the environment. While the growth of salmon farming has been enormous, current practices do pose significant environmental challenges. In Japan, mariculture of seaweed is particularly important.
Modern Cultural Connections
The entertainment industry has capitalized on the fact that people find marine organisms exotic and fascinating, beginning with the 1964 television show Flipper. The National Geographic, Public Broadcasting, and Travel Channels, among others, regularly feature documentaries about marine organisms. In 2001 BBC1 produced an extraordinary series called The Blue Planet that explored life in the oceans from pole to pole, and from the deep ocean to the coastline. The BBC and the Discovery Channel also coproduced Planet Earth, launched in 2006. Filming never-before-seen animal behaviors, the series, produced in high-definition television, includes beautiful footage of animals from both the deep ocean and the shallow seas.
Marine biology has also played a starring role in the film industry. Numerous movies focus on marine organisms, including the popular movies, Jaws (1975), Whale Rider (2002), Finding Nemo (2003), and Happy Feet (2006). The IMAX film Deep Sea (2006) focused on relationships among marine organisms throughout the ocean. In that same year former American Vice President Al Gore released the award-winning film An Inconvenient Truth, which discusses climate change. The film won an Academy Award and generated much public debate on changes in Earth's climate and the possible implications for life on the planet, including marine organisms. Although some of the film' contentions were challenged by critics as misleading or even incorrect, Gore won the Nobel Peace Prize in 2007, along with the International Panel on Climate Change, for work in bringing climate change to global attention.
Increased awareness has helped establish scores of nonprofit foundations focused on safeguarding the environment for marine species. Examples include the Cousteau Society, Greenpeace, Marine Resources Development Foundation, Natural Resources Defense Council, Sea Shepherd Conservation Society, Oceans Conservancy, World Wildlife Fund, and Coral Reef Alliance, among others.
The popularity of marine biology in common culture has had interesting and far-reaching consequences. In 2005 DiamlerChyrsler challenged a design team to build a highly efficient and aerodynamic vehicle. Taking their cues from nature, the group discovered a small boxfish, Ostracion cubicus, found in coral reefs and tropical lagoons. Though awkward looking, the fish turned out to be extremely streamlined, with drag coefficients close to that of aerodynamically ideal shapes, like a drop of water. The concept car based on the boxfish shape has 20% better fuel efficiency than other vehicles in its category. Boxfish skin is composed of hexagonal plates, which give the fish rigidity and weight efficiency. A similar structure was incorporated into the concept car, giving it 40% more rigidity than would be achieved with traditional designs.
As research in marine biology has grown, so too has the opportunity for a career within the field. It is estimated that several thousand marine biologists work in the United States. Approximately 40% are employed by government agencies, 30% at universities, and 30% in private industry. With the growing awareness of global climate change and concern over its effects on environments, including the ocean, employment opportunities in marine biology are expected to continue to grow.
Primary Source Connection
Recent international controversies regarding whaling have the International Whaling Commission (IWC) searching for solutions to balance cultural practice with species protection. The International Convention for the Regulation of Whaling bans commercial whaling, but not all species of whale (Cetaceans) are, in reality, protected because not all countries observe the prohibitions. The Convention is an international agreement in effect since 1948 designed to make commercial whaling sustainable. It established the International Whaling Commission, a British-based international regulatory body, which governs the conduct of whaling throughout the world.
In addition to protecting species and biodiversity, the Commission seeks to permit only sustainable whaling, the process by which a limited number of whales from thriving species, such as the minke, are culled each year
Whaling, the hunting and killing of whales, dates back centuries. Native people like the Macah, Nootka, and Coastal Salish of the Pacific Northwest are known to have hunted whales nearly 2,000 years ago. Whaling became economically important to Europeans when they colonized North America in the late 1600s. By 1672, whaling parties were organized off of Cape Cod in Massachusetts and off of Long Island in New York. However, by the early 1700s, the number of whales venturing close to shore had already begun to decline, so larger ships called sloops were developed that could capture whales farther off shore.
By the late 1800s, whaling had become a thriving commercial industry. Two of the most commonly hunted whales were the right whale and the sperm whale. The right whale was so named because it was the “right” whale to catch. It floated after it was killed, and so it was easy to recover from the ocean. Sperm whales were highly prized for their spermaceti, an oil found in their heads and used for making candles.
Whales had a variety of commercial uses. Whale oil was used for lubrication, lighting, cosmetics, and food. Whale bones were ground and sold as fertilizer and animal feed supplements. The baleen (horn-like substance that hangs from the upper jaws of some whales) from whales was once commonly used in women's corsets (an undergarment). A type of fat called ambergris was occasionally found in the intestines of whales and was used to make perfume. Today, there are substitutes for all of the products that whales once supplied.
In December 1946 longstanding efforts by the world's whaling nations to exert control over the whaling industry and protect against over-hunting produced the International Convention for the Regulation of Whaling (ICRW). Originally signed by 15 nations in Washington, D.C. on December 2, 1946, it came into effect nearly two years later, on November 10, 1948.
The whaling industry of the early twentieth century quickly overwhelmed the stocks of whales in the ocean. It is estimated that 4.4 million large whales swam in the oceans in 1900. By 2004, the estimates were that only 1 million remained. Of the 11 species of whales that are commonly hunted, in 1999, 8 were commercially extinct, which means that they are too rare to justify the expense of hunting. The blue whale is in danger of becoming totally extinct (no longer in existence). When commercial blue whale hunting ended in 1964, only about 1,000 animals were left, and that may ultimately prove too small a number for the population to recover.
The IWC banned all commercial whaling in 1986. Because their countries depend on a whaling industry, Norway withdrew from the IWC in 1993 and Iceland withdrew in 1996. Japan never stopped hunting whales, even when the ban was in place. These three countries currently hunt the relatively plentiful minke whales.
Several whale sanctuaries have been imposed by the IWC. The Indian Ocean Sanctuary, established in 1979, prevents whaling in the southern Indian Ocean, in the feeding grounds of many large whales. In 1994, the IWC voted to make the oceans around Antarctica—where many species of large whales feed—a conservation area from whales. This sanctuary neighbors the Indian Ocean Sanctuary. Unfortunately, this sanctuary is often ignored. Both Norway and Japan have killed whales in these waters since the sanctuaries were established.
Despite controversy, the conservation efforts of the IWC have resulted in increases in numbers of whales. Since the commercial whaling ban was put in place, estimates of blue whales off the coast of California increased from 500 in 1979 to more than 2000 in 1991. Similarly, approximately 88 humpback whales were observed off the coast of California in 1979, while more than 600 were observed in 1991. The California gray whale was nearly extinct in 1986. Since then, its numbers have rebounded dramatically to approximately 26,000 animals in 2000. In 1993, it was removed from the endangered species list.
Scientists have long debated just how smart marine mammals such as whales are. Although it is difficult to measure whale intelligence, based on recent science the author of the following primary source concludes that whales “[that] were previously regarded as ‘living marine resources’ … should now be recognised as unique individuals, communities, societies and cultures and valued as such.”
INTO THE BRAINS OF WHALES
The mammalian order Cetacea includes over 80 known species of whales, dolphins and porpoises and is popularly believed to contain some of the most intelligent animals. Although research on cetacean social systems lags some three decades behind equivalent work on primates, new research and expert analyses of research and behaviour mean that, whilst acknowledging the limitations of our present understanding, we can now engage in a well informed consideration of cetacean intelligence, society and culture and attempt to relate our conclusions to urgent conservation and welfare issues.
However, there are a number of significant methodological difficulties involved in evaluating cetacean intelligence. Lusseau and Newman (2004) noted that “animal social networks are substantially harder to study than networks of human beings because they do not give interviews or fill out questionnaires…” Consequently, information must be gained by direct observation of individuals and their interactions with conspecifics. However, when studying marine mammals, the practical difficulties and expense involved in observational work are considerable, including the fact that individuals tend to be wide-ranging, fast moving and, in the case of several species, also very deep-diving. This has lead to the development of stringent photo-identification techniques which in recent years have provided an important insight into cetacean social networks. A further complication is the degree to which the cetacean behaviour observable at the sea surface reflects their activities more generally. This is especially true of the deep divers such as the beaked whales of the family Ziiphidae or the cachalots (or sperm whales), Physeter macrocephalus, which spend so much of their time in the depths. In the case of the latter in particular, studies at the surface are now being combined with sophisticated acoustic techniques which enable the animals to be monitored underwater, including monitoring particular individuals.
Another tier of complexity is provided by the likelihood that physically proximate individuals, apparently operating as a distinct group, may actually be in acoustic contact with other more distant animals creating a larger, dispersed social unit that is far more difficult to study. Janik recently calculated that the wild common bottlenose dolphin, Tursiops truncatus, whistles in the Moray Firth, Scotland, could be discernable 20–25 km away (in water of 10 m depth and with a sea state of zero). The larger, louder whales may be in contact across entire ocean basins. In fact, cetaceans predominantly perceive their world using sound and remarkable hearing abilities; a distinction that makes comparison with primates difficult.
Another methodological issue is the anatomical differences between cetaceans and primates. Goold and Goold in The Animal Mind commented “… privately many primatologists (and publicly a few) concede that they assume that their subjects are to some degree self aware. In part this may arise not because primates are so much smarter than others species, but because it is easier for humans to read primate gestures and emotional expressions than the equivalents in, say, beavers or dolphins. It is also easier for us to empathize with behavioural responses to situations that could touch our own lives.” Thus they highlight the possibility that our interpretation of cetacean behaviour might be hampered by a lack of empathy which could also have significant implications for conservation priorities and welfare issues.
In terms of behavioural interpretation, the physical differences between primates and cetaceans are significant. For example, whilst the arrangement of bones in the cetacean forelimb is similar to our own, the phalanges are encased within a flipper, which acts as an aqua-foil for lift and steering. Thus they lack the manipulative abilities of primates and cannot gesture or point with the same facility. Similarly, the musculature of their heads prohibits facial expressions, although a few species such as the beluga, Delphinapterus leucas, have some “facial” mobility.
From their work on primates, Russon and Bard identified the following signs of intelligence: problem solving by insight; tool use/manufacture; imitation; sense of self; pedagogy and culture. This paper reviews the recent key literature and results concerning relevant cetacean attributes in these key areas and, additionally, considers some evidence that suggests emotional responses in cetaceans. It is also worth commenting at the outset that two evolutionary pressures on cetaceans are likely to have resulted in the development of high cognitive functioning: firstly the patchy un-predictable prey resources that they tend to exploit and, secondly, the cognitive demands of living in complexly bonded social groups….
3. Examples of Intelligent Behaviours
Brain size and comparative development is, at best, only an indicator of intelligence and a better way to assess intelligence may be to look at behaviour, including communication skills. Captive cetaceans, especially bottlenose dolphins and orcas, Orcinus orca, have successfully been taught to repeat a wide range of actions. In fact, bottlenose dolphins modify taught behaviours and invent new ones (Norris, 2002). They appear to make their play more complex and difficult over time, arguably a “hallmark of intelligence” and innovative play is also known in wild dolphins.
The bottlenose dolphin can imitate both vocally and non-vocally and is considered by some to be the most sophisticated non-human imitator. Herman suggests that the extensive vocal and behavioural mimicry of the dolphins is “a seemingly unique combination of abilities among non-human animals” and notes that dolphins can copy behaviours and sounds without extensive repetition or training. Behavioural fads have also been seen to spread spontaneously among captives.
Bottlenose dolphins have also shown that they can learn and generalise a variety of reporting tasks. This includes reporting on named objects in their environment; reporting on the behaviour of others (including other dolphins, humans and seals) by mimicry; reporting their own behaviour. From their experiments, Mercado et al. suggest that dolphins can “flexibly access memories of their recent actions” that are of sufficient detail for reenactment.
For example, bottlenose dolphins will “point” at objects to guide humans to them. They do this by stopping their forward progress, often less than 2 m from an object, aligning their anterior-posterior axis for a few seconds and then alternating head direction between the object and the trainer. These pointing behaviours are affected by the degree of attentiveness of the experimenters, and do not occur with humans absent.
Despite their lack of fingers and thumbs, both wild and captive dolphins may spontaneously manipulate objects. There is one well-documented use of tools in a wild Indo-Pacific bottlenose dolphin, Tursiops aduncus, population which occurs in Shark Bay, Australia. The animals (almost exclusively females) are often seen carrying sponges on the ends of their beaks probably to protect them whilst they forage in the sediments on the seafloor where spiny sea urchins might otherwise cause puncture wounds.
Another example of manipulation involves the bubbles that dolphins produce underwater. Breathing is a voluntary activity in cetaceans and the bubbles may be released in streams, clouds or as single bubble-rings. Although the physics that create these doughnut-shaped bubble formations are well understood (a bubble bigger than two centres in diameter tends to become a ring because of pressure differences between the top and bottom), the production of stable rings probably requires practice, expertise and forethought (McCowan et al., 2000). Dolphins manipulate their bubble rings by forming vortices around them, causing them to flip, turn vertically or fuse. McCowan et al. concluded that this form of manipulation was consistent with at least “low level planning” prior to bubble production, again implying self-monitoring. They also report anecdotal evidence that young dolphins learn to produce rings from their mothers….
The issue of cetacean intelligence has been very controversial in the last few decades and the enthusiasm of some popular authors for promoting cetaceans as highly intelligent in the 1960s arguably caused a counter-productive back-lash with skeptics highlighting lack of rigorous scientific proof, reliance on anecdotal information and failure to separate instinct from intelligence. Gaskin underpinned his very thoughtful—and still widely cited—criticism by asking two basic questions:
(1) Is there any real social structure in cetacean populations?
(2) Do cetaceans have highly developed social behaviour?
We now have the benefit of more than two decades of further and increasingly sophisticated research which has shown relationships and behaviours that were hinted at in Gaskin's day. I therefore propose that the answer to Gaskin's two primary questions is now, for some species at least, an unequivocal “yes.”
[There is an]…emerging body of evidence for the advanced cognitive abilities of some cetaceans… [I]f we accept this perspective, the next question is how should this knowledge affect our interactions with these animals?…
- It has been estimated that some 200,000 cetacean are killed annually in fishing nets.
- The last available data for Japanese whaling reveal that only 40.2% of animals die “instantaneously”…
- “A blue whale, which lives 100 years, that was born in 1940, today has had his acoustic bubble shrunken from 1000 to 100 miles because of noise pollution.”
There is not room here to fully explore the relationship between the intelligence of these animals and the conservation and welfare matters that affect them, but it is clear that deaths in hunts and fishing nets may often be prolonged and painful and also significantly affect more members of the population than just the animals killed. It is also clear that we are having a widespread impact on their environment. Our relationship with these animalstherefore needs to move to a new paradigm. What were previously regarded as “living marine resources”—and typically widespread species distributed across an inexhaustible sea—should now be recognized as unique individuals, communities, societies and cultures and valued as such.
Mark Peter Simmonds
simmonds, mark peter. “into the br ains of whales,” applied animal behaviour science 100 (2006): 103–116.
Primary Source Connection
Marine scientists have paid increasing attention in recent decades to the plight of coral reefs worldwide. Most corals are sensitive to changing ocean temperatures and vulnerable to pollution. Because they are relatively slow growing and sensitive to environmental changes, coral reefs are a good measure of ocean health. By studying corals, researchers can track changes in ocean currents, temperature, and chemistry over centuries. Understanding these changes gives insight into the impact of pollution and global climate change on reef ecosystems.
The consensus of the marine scientific community is that almost all of the world's coral reefs are in peril. However, reef preservation faces several challenges. Not only is research and preservation costly, but coral reefs are also an integral part of many peoples' livelihood. Hundreds of thousands of people worldwide make their living from coral reefs, especially in developing regions. Fishing, sponge and coral collection, and tourism fuel many local economies but can negatively impact coral reefs. While preservation efforts are helping to rejuvenate limited coral populations worldwide, some critics note that restoration efforts too often focus on the reefs that are the most popular with tourists.
CORAL IS DYING. CAN IT BE REBORN?
Clouds were moving across the sun and a 20-knot northeast wind was stirring a 3-foot chop as Meaghan Johnson headed her open boat into the Florida Straits.
Ms. Johnson, a program coordinator for the Nature Conservancy, headed the boat into the swells, to minimize swamping, as her passengers tried in vain to avoid soaking spray.
One of them, Ken Nedimyer, stood next to her at the console, gazing out at the seemingly featureless welter of waves, seeking signs—a slight change in water depth here, a barely visible underwater patch of reef there—that only he could recognize and triangulate with the rapidly disappearing onshore landmarks of Key Largo.
About two and a half miles out, he told Ms. Johnson to throttle back a bit. “Over there,” he said, pointing off the starboard bow. “About 400 yards.”
The boat pulled up to the site and Philip Kramer, who directs the conservancy's Caribbean Marine Program, set its anchor. Soon he, Ms. Johnson and Mr. Nedimyer were over the side, peering into the water through their snorkeling masks. Below them was what they had come to see, an array of concrete disks set in the sand. Each one held a tiny piece of coral.
Mr. Nedimyer had led them to a nursery, one of a number he has established since 2000, when chance, coincidence, a government program and a lifelong passion for tropical fish set him on an adventure: a quest to nourish and restore the tattered remains of the Keys' once glorious reefs.
He is working with assistance from the conservancy, which in turn cooperates with the Florida Keys National Marine Sanctuary and the National Oceanographic and Atmospheric Administration, which has its own coral efforts in places like Puerto Rico. Meanwhile, the Environmental Protection Agency is looking at water quality standards for corals in Florida, Hawaii, the Virgin Islands and Puerto Rico, the only American territories where they occur. The Coral Reef Task Force, created in the Clinton administration, regularly assesses coral health. The World Bank, motivated in large part by corals' importance for ecosystems and ecotourism, has embarked on a global program to assess restoration efforts and to identify tactics to combat their decline.
And 90 miles south on Highway 1, the traffic-snarled spine of the Keys, biologists at the Mote Marine Laboratory struggle with their own coral nursery efforts. Like Mr. Nedimyer, they are trying to identify strains of coral that grow well in the Keys, and to re-establish them offshore.
Theirs is an uphill battle. Many would say corals globally are already so damaged, and so threatened by further environmental degradation, that there is little chance restoration efforts can turn things around.
Staghorn and elkhorn corals, Mr. Nedimyer's principal interests, were once abundant in South Florida, the Bahamas and elsewhere in the Caribbean. But since the 1990s they have significantly declined, to the point that last year they were placed on the threatened list, under the Endangered Species Act.
They are suffering the kinds of environmental disruption that afflict corals around the world. “We have lost 25 percent of the world's corals in the last 25 years,” David E. Vaughan, director of the Center for Coral Reef Research at Mote, said in an interview, adding that 25 percent more are expected to die in the next decade or two. “Sometimes we sound like doomsday sayers,” Dr. Vaughan said, “but those are the facts.”
Environmental disruption takes many forms. Fishing boats, and even dive boats and divers, can damage reefs. Sea turtles bang into corals, breaking them. Polluted runoff can deprive corals of the clear, oxygen-rich water they need to survive.
And then there is global warming. So far, scientists say, it has had two main effects on coral, both potentially lethal. First, as oceans absorb more carbon dioxide, the chief greenhouse gas, they become more acidic. The acidity makes it more difficult for corals to grow and may even cause them to start to dissolve. And as oceans warm, algae that live in corals, and on which they depend, may be killed.
David Lackland, a biologist at Mote, tells children who visit that corals live with algae as people might live if they liked asparagus, say, but instead of raising it in gardens they grew it inside their bodies, absorbing it directly as energy and fertilizing it with their waste in a symbiotic relationship. Different kinds of corals have different kinds of algae symbionts, but if the algae are threatened, corals are threatened, too.
Another serious disruption is overfishing.
Corals need herbivorous fish to keep unwanted algae under control. When seaweed-eating fish are gone, “you are going to end up with seaweed blooms,” said Nancy Knowlton, director of the Center for Marine Biodiversity and Conservation at the Scripps Institution of Oceanography and a leader in the World Bank effort. “It's been shown that seaweeds release a lot of sugars into the water,” she said. Because many bacteria need sugars, “you have these bacteria blooms that kill corals.”
Corals also need predators like groupers, snappers, barracudas and even lobsters to prevent the proliferation of coral-eating snails, worms and other organisms.
Meanwhile, a host of diseases plague coral, many of them poorly understood. For example, staghorn and elkhorn coral are vulnerable to so-called white-band disease, in which coral tissue mysteriously decays. The disease, which struck the Caribbean in the mid-1990s, kills healthy tissue, leaving only white skeletons. It usually progresses quickly, and while it almost never wipes out complete colonies, colonies can be reinfected.
Scientists do not know for sure what causes the condition, and their suspects—bacteria, fungi and other microbes—are present at healthy corals as well as sickly formations, adding to the mystery.
Corals in South Florida have another big problem, a die-off of sea urchins, which began succumbing wholesale to a mysterious ailment about 20 years ago. Urchins graze on unwanted algae, and without them, corals in many areas have been smothered in overgrowth, making it difficult or impossible for them to grow or propagate.
Mr. Nedimyer focuses most of his efforts on coral, something he got into almost by accident several years ago, through his work as a wholesale dealer in aquarium supplies, a business he has operated for 35 years. One of his products is “live rock,” reef rubble that bacteria colonize. In aquariums, the bacteria help break down waste from fish.
He had permission from the government to gather live rock at a particular site and one day about 10 years ago, he noticed that a few bits of rubble had something growing on them. “I didn't know what it was at first,” he said. “I saw five of these little things. I kept watching them and pretty soon they started to grow out into staghorn coral.” He set the rocks aside, underwater, and managed to keep the coral growing in spite of storms and other problems. When he found broken pieces of coral he stuck them in other pieces of rock, and “sometimes they would live.”
In 2000, at an aquarium in Orlando, he heard a presentation on Pacific coral and learned that “you can cut these things into tiny fragments and glue them to things and they will grow.” Back in the Keys, he started experimenting. His daughter Kelly helped, turning the work into a 4-H project.
At first it was trial and error. They experimented with growing platforms and especially with how to glue coral fragments to them. “We tried a lot of epoxy,” Mr. Nedimyer said. “We found kinds that stick to wetsuits, to hair, to cameras.”
Eventually, they discovered a two-part epoxy glue used in taxidermy. They can mix it on a boat and it remains workable for about half an hour. And it is white, which looks nice against the sandy bottom.
For a brief heady moment, he recalled, he thought about the fact that he has government permission to sell coral and considered turning it into a lucrative sideline for his business. But then, he said, he started thinking about what had happened to the Keys' reefs since he first encountered them in the 1970s, “when there would be thickets three, four, five feet high and just vast.”
Those kinds of underwater landscapes have just about vanished, he said. “So I thought, well, these corals are in trouble. And we can make a difference rather than make money.” Today he has several nurseries, each with a variety of coral strains, at varying depth, water quality and distance from shore. The goal of the project is to identify which coral strains are most robust and in what conditions. Dr. Kramer, Ms. Johnson and Mr. Nedimyer were pleased by the corals they saw at the nursery. After climbing back into the boat, Mr. Nedimyer said: “They were a few inches, now they are two or three times the size. That's a lot of growth in six months.”
Dr. Knowlton, the coral expert at Scripps, said staghorn coral was among the fastest growing—up to four inches or so from branch tips in a year, whereas most corals grow only about half an inch a year. But, she said, corals that grow quickly are often unusually sensitive to their environment. “They can slip from growing really fast to dying really fast,” she said.
At Mote, Mr. Lackland maintains and propagates a variety of coral species in tanks, and hopes to emulate Mr. Nedimyer with offshore nurseries between Looe Key and American Shoals.
Like Mr. Nedimyer, Mr. Lackland, who is 40, parlayed a youthful fascination with marine creatures—he had corals in tanks in his bedroom as a teenager in Watchung, N.J.—into his life's work. After earning a bachelor's degree in biology, he worked at an aquarium in Point Pleasant Beach, N.J., where his one-bedroom apartment had six tank systems filled with coral. Friends told him he had “a blue thumb.”
Eventually, he said, he decided to go to the Florida Keys, “where they have the most hurting ocean, an ocean that's slipping away as far as its coral cover.” He presented himself at the National Marine Sanctuary, where he learned there might be an opening for a biologist at Mote. When he got the job, “I was thrilled,” he said.
Today, he presides over several rooms full of tanks where many species of coral grow on networks of iron pipes. Mr. Lackland has devised elaborate systems to mimic the flow of ocean currents, the varying pressure of waves and even the coming and going of daylight. He feeds his coral oyster larvae and other plankton, which he buys from an aquarium supplier, and he has devised formulas to maintain the proper mineral balance in the water.
Some of his corals are doing so well they have even spawned in the tanks.
Like Mr. Nedimyer, he is starting corals on concrete disks and establishing them in the water, in his case between Looe Key and American Shoals, near the laboratory.
Dr. Kramer noted that, over all, “corals have managed to deal with many swift changes in the last million and half years.” He added, “Over these geological time scales, in the long term, corals may be able to handle these climate changes.” Meanwhile, though, he said, “I think these types of strategies have a real role to play.”
For scientists like Dr. Knowlton, the major question is not whether some coral strains might do better than others. That is almost a given, she said. “The biggest problem is making a difference on a regional scale or even on a large local scale.”
She said people interested in corals should focus on “fixing the things we can fix—climate action or water quality action or stopping overfishing.”
In interviews, Mr. Lackland and Mr. Nedimyer separately acknowledged that viewed from any reasonable perspective, the problem is huge and their efforts are small.
“I am not an ostrich,” Mr. Lackland said. “The facts are really bad.” But, he added, “If the ocean is really in that bad condition, let's gear up!”
Mr. Nedimyer shares this view even though, as he put it, every day he spends on the project “is one day I can't make a living.” But one of its major rewards, he said, was its lesson for his daughter Kelly, now 19 and a student at the University of Central Florida, and the Coral Shores students working with him. “We have turned five corals into five to seven hundred,” he said. “In another year or two we'll have several thousand corals. That's mostly one person making a difference.”
Correction: May 7, 2007, Monday An article and picture caption in Science Times on Tuesday about efforts to re-establish coral reefs referred incorrectly to the networks of pipes on which coral is grown in the Mote Marine Laboratory in Florida. The pipes are made of PVC, not iron. The article also carried an incomplete list of American territories where corals occur. Besides Florida, Hawaii, the Virgin Islands and Puerto Rico, corals also grow in warm and cold water in several other areas, including American Samoa and the Gulf of Mexico off the coast of Louisiana and Texas.
dean, cornelia. “cor al is dying. can it be r eborn?”
new york times (may 1, 2007): F:1.
See Also Biology: Botany; Biology: Classification Systems; Biology: Comparative Morphology: Studies of Structure and Function; Biology: Developmental Biology; Biology: Evolutionary Theory; Biology: Miller-Urey Experiment; Biology: Ontogeny and Phylogeny; Biology: Paleontology; Biology: Zoology.
Earth Science: Climate Change; Earth Science: Geography; Earth Science: Oceanography and Water Science.
Castro, Peter, and Michael E. Huber. Marine Biology. 6th ed. New York: McGraw-Hill Science/Engineering/Math, 2006.
Garrison, Tom. Oceanography: An Invitation to Marine Science. 5th ed. Stamford, CT: Thompson/Brooks Cole, 2004.
Karleskint, George, Richard Turner, and James Small. Introduction to Marine Biology. 2nd ed. Belmont, CA: Brooks Cole, 2006.
Lerner, K. Lee, Brenda Wilmoth Lerner, and Lawrence W. Baker, eds. UXL Encyclopedia of Water Science. Detroit: UXL, 2005.
Prager, Ellen, and Sylvia A. Earle. The Oceans. New York: McGraw-Hill, 2000.
Sumich, James L., and John F. Morrissey. Introduction to the Biology of Marine Life. 8th ed. Boston: Jones and Bartlett, 2004.
Dean, Cornelia. “Coral Is Dying. Can It Be Reborn?” New York Times (May 1, 2007): F:1.
Simmonds, Mark Peter. “Into the Brains of Whales,” Applied Animal Behaviour Science 100 (2006): 103–116.
American Association for the Advancement of Science: Eurekalert. “Smithsonian Scientists Discover New Marine Species in Eastern Pacific.” March 8, 2007. http://www.eurekalert.org/pub_releases/2007-03/stri-ssd030807.php (accessed March 12, 2007).
BBC News. “NZ Fishermen Land Colossal Squid.” February 22, 2007. http://news.bbc.co.uk/2/hi/asia-pacific/6385071.stm (accessed March 2, 2007).
BBC News. “Save the Whale, Save the Planet.” June 12, 2000. http://news.bbc.co.uk/2/hi/uk_news/787425.stm (accessed December 2, 2007).
Census of Marine Life. “Gulf of Maine Area Program.” January 3, 2006. http://www.usm.maine.edu/gulfofmaine-census/ (accessed March 2, 2007).
DaimlerChrysler. “The Mercedes-Benz Bionic Car as a Concept Vehicle.” June 7, 2005. http://www.daimlerchrysler.com/dccom/0-5-7154-1-503502-1-0-0-503518-0-0-135-7145-0-0-0-0-0-0-1.html (accessed March 2, 2007).
Marine Biological Laboratory. “Biological Discovery in Woods Hole.” http://www.mbl.edu/ (accessed March 2, 2007).
Marine Biological Laboratory. “The Horseshoe Crab: Limulus polyphemus.” http://www.mbl.edu/marine_org/images/animals/Limulus/index.html (accessed June 7, 2007).
Museum of Science. “Oceans Alive: The Living Sea.” http://www.mos.org/oceans/life/index.html (accessed June 7, 2007).
Poseidon Ocean Sciences, Inc. http://www.poseidonsciences.com/index.html accessed June 7, 2007).
University of California, Marine Environmental Education and Research. “A Brief History of Marine Biology and Oceanography.” http://www.meer.org/mbhist.htm (accessed June 7, 2007).
University of Rhode Island, Office of Marine Programs. “Census of Marine Life: Making Ocean Life Count.” http://www.coml.org/ (accessed June 7, 2007).
Woods Hole Oceanographic Institution. http://www.whoi.edu/ (accessed March 2, 2007).
"Biology: Marine Biology." Scientific Thought: In Context. . Encyclopedia.com. (March 26, 2019). https://www.encyclopedia.com/science/science-magazines/biology-marine-biology
"Biology: Marine Biology." Scientific Thought: In Context. . Retrieved March 26, 2019 from Encyclopedia.com: https://www.encyclopedia.com/science/science-magazines/biology-marine-biology