Dragonets and Relatives: Callionymoidei
DRAGONETS AND RELATIVES: CallionymoideiLANCER DRAGONET (Paradiplogrammus bairdi): SPECIES ACCOUNT
Dragonets and their relatives are small and have a long flat body with a broad flat head. Dragonets usually have two dorsal fins, the first having one to four spines. The dorsal fins of some males are large and high and have long rays, or supporting rods. Dragonets also have large pelvic and pectoral fins. The dorsal (DOOR-suhl) fin is the one along the midline of the back. The pelvic fins correspond to the rear legs and the pectoral (PECKter-uhl) fins to the front legs of four-footed animals.
The bone in front of the gill cover of dragonets has spines. The body has no scales. Many species of dragonets have camouflage coloring, but others are brilliantly colored. Some species produce a bitter-tasting slime that covers their bodies and may serve as protection from predators (PREH-duh-ters), or animals that hunt and kill other animals for food.
Draconetts have small, long, tubular bodies, large pectoral fins, and long pelvic fins. They have no scales. These fishes have large eyes. There are two dorsal fins, with the first having three spines. There are strong spines around the gill covers.
Dragonets and their relatives live in the Atlantic, Indian, and Pacific oceans.
Most dragonets live on coral, rubble, sand, mud, and other soft bottoms. Some live among algae-covered rocks or mangrove roots in water with a low salt content. Little is known about the habitats of draconetts. They probably live in rubble and sand or among rocks. Algae (AL-jee) are plantlike growths that live in water and have no true roots, stems, or leaves.
Dragonets and their relatives eat small, bottom-dwelling invertebrates, or animals without backbones. Larger species eat larger animals.
BEHAVIOR AND REPRODUCTION
Male dragonets use their long first dorsal fins for male-to-male fights and male-to-female courtship. Almost nothing is known about the behavior of draconetts. Their large eyes probably aid them in movement, feeding, and reproductive behavior in deep bottom habitats.
Males dragonets defend their territory when they are reproducing. In courtship a male approaches a female, displays his spread-out fins to her, and, as if carrying her, rises with her a short distance in the water, where free-floating eggs are released and fertilized (FUR-teh-lyzed), or united with sperm to start development. Almost nothing is known about reproduction of draconetts. Mating is probably paired and takes place in open water with a rapid, short rise in the water, where eggs and sperm are released.
DRAGONETS, THEIR RELATIVES, AND PEOPLE
Dragonets are important aquarium fish. Draconetts do not appear to have any importance to humans.
The World Conservation Union (IUCN) lists one species of dragonets and their relatives as Critically Endangered, or facing an extremely high risk of extinction in the wild.
Physical characteristics: Lancer dragonets reach a total length of about 4 inches (11 centimeters). Males are larger than females, have larger fins, an extended dorsal fin, and bolder color patterns on the body and fins. The body is long and has no scales. These fish have four spines on the first dorsal fin. The color pattern varies between sexes. The top half of the body has marbling and mottling in shades of brown, black, and white. There are white, roundish blotches between narrow brown bars on the bottom half of the body. The first dorsal fin of males has a yellow swirl, and the second dorsal fin has a downward-pointing pattern of dark bands. Males also have blue lines and rows of spots on the first dorsal fin; blue bars with narrow orange edges on the first bone of the gill cover; orange spots, small blue lines, and crescent-shaped markings on the top half of the body; and blue spots around the bottom half of the body and the eyes.
Habitat: Lancer dragonets are bottom dwellers. They live on sand patches on shallow reefs, rocky shorelines, and sea-grass flats at depths of 3 to 300 feet (1 to 91 meters).
Diet: Lancer dragonets eat small bottom-dwelling invertebrates.
Behavior and reproduction: Lancer dragonets take advantage of their camouflage coloring as they forage for food along the bottom. Males defend their territories and females by displaying their fins. Males also begin courtship by displaying their fins to females. These fish spawn in pairs after rising a short distance in the water, where the eggs are fertilized. Eggs drift in a mass in the water. The egg mass breaks up before hatching.
Lancer dragonets and people: Lancer dragonets are collected for aquariums.
Conservation status: Lancer dragonets are not threatened or endangered. ∎
FOR MORE INFORMATION
Allen, Gerald. Reef Fish Identification: Tropical Pacific. Jacksonville, FL: New World, 2003.
"Dragonets." Life at the Edge of Reef. http://www.edge-of-reef.com/callionimidi/callionimidien.htm (accessed on November 1, 2004).