BATHYNELLACEANS: Bathynellacea

PHYSICAL CHARACTERISTICS

Bathynellaceans (bath-ee-nel-AYS-see-ans) range in length from 0.02 to 0.14 inches (0.5 to 3.5 millimeters). They do not have eyes and lack any body coloration. The body is divided into a head, thorax, and abdomen. The head may or may not have a beaklike projection, or rostrum. The first pair of antennae, called antennules, is uniramous, or unbranched. The segmented thorax has seven or eight pairs of simple biramous, or branched, legs. There are no leglike thoracic limbs associated with the mouthparts. The six-segmented abdomen may or may not have one or two pairs of small limbs. Bathynellaceans do have a pair of limbs on the end of the body called uropods. The uropods are found on either side of a central projection, or telson.

GEOGRAPHIC RANGE

Bathynellaceans are found on all continents except Antarctica. They are not known to be from Central America, from islands that are volcanic in origin, and from some other islands, such as New Caledonia, Fiji, and the Caribbean islands.

HABITAT

Bathynellaceans are found mostly underground near freshwater habitats or in caves. They are sometimes collected on the surface in waters that are fed by underground water sources, such as wells, in sands along the shores of rivers and lakes, or in springs. At least one African species lives in hot springs and can tolerate temperatures up to 130°F (55°C). A few species can tolerate slightly salty water and are found near the seashore or in other brackish waters.

DIET

Bathynellaceans eat plant materials, worms, microscopic animals, and bacteria. Some species may be specialists and feed on just one or two of these groups of organisms.

BEHAVIOR AND REPRODUCTION

Bathynellaceans crawl through the sand with a combination of swimming and walking movements. Although they are very awkward swimmers in open water, they are extremely agile animals and move easily through the narrow spaces between grains of sand.

Although both male and female bathynellaceans are known, their mating behavior has never been observed. Unlike most crustaceans that carry their eggs or young, female bathynellaceans lay their eggs one at a time in the surrounding sand. The young animal hatches from the egg as a larva with only working antennae and mouthparts. Adulthood is reached through a series of molts, or shedding of the exoskeleton. Additional appendages are added with each molt. The number of molts varies among species.

BATHYNELLACEANS AND PEOPLE

Bathynellaceans help to improve water quality and flow by breaking down bits of plants and animals that wash into underground water systems.

TAPPING IN TO BATHYNELLACEANS

Bathynellaceans eat bits of plants and animals washed into the ground from the Earth's surface. Bacteria, fungi, and other microscopic organisms break down in their waste products. These activities help to clean the water and keep it flowing through the filtering sands that surround underground springs. Without these organisms these natural filters would soon become clogged and prevent the flow of fresh, clean water from underground sources into wells, springs, lakes, and rivers.

CONSERVATION STATUS

No species of bathynellaceans are considered endangered or threatened.

NO COMMON NAME (Antrobathynella stammeri): SPECIES ACCOUNT

Physical characteristics: Males and females have a row of four spines at the base of the uropods. The spine closest to the front of the body is larger and distinctly separated from the others. The base of the seventh leg of the male has a clear, cone-shaped bump on the inside.

Geographic range: Antrobathynella stammeri are widely distributed in Europe, from Ireland to Romania.

Habitat: Antrobathynella stammeri are found in underground springs and all surface habitats fed by them.

Diet: They eat bits of plant materials and worms.

Behavior and reproduction: Antrobathynella stammeri are agile crawlers soon after they hatch from the eggs.

This species reproduces throughout the year. The young take about nine months to reach adulthood. Adults must continue to molt before they can reproduce. Adult males molt four times and females five. Animals in captivity live up to two years, probably longer in the wild.

Antrobathynella stammeri and people: This species probably contributes to keeping underground springs fresh and flowing.

Conservation status: Antrobathynella stammeri is not considered endangered or threatened. ∎

FOR MORE INFORMATION

Books:

Coineau, N. Syncarida. In Encyclopaedia Biospeologica 2, edited by C. Juberthie and V. Decou. Bucarest, Romania: Société de Biospéologie, 1998.

Web sites:

Lowry, J.K. Crustacea, the Higher Taxa: Description, Identification, and Information Retrieval. Version 2 October 1999. http://crustacea.net/ (accessed on February 15, 2005).

Syncarida.http://www.lucidcentral.com/keys/lwrrdc/public/Aquatics/adcrust/html/SYNCARID.htm (accessed on February 15, 2005).