Coelacanths and Lungfishes: Sarcopterygii

Physical characteristics: Lungfishes have eel-like bodies and long, thin pectoral and pelvic fins. The skeleton is mostly cartilage (KAR-teh-lej). These fishes have two lungs and small gills, or organs for obtaining oxygen from water. South American lungfishes can grow to a length of 4 feet (1.25 meters). They are dark brown or gray and have dark and light spots on the top and sides.

Geographic range: South American lungfishes live in the Amazon River basin and in French Guiana.

South American lungfish have lungs and small gills. (©Tom McHugh/Photo Researchers, Inc. Reproduced by permission.)

Habitat: These lungfishes live in swamps, slow-moving rivers, floodplains, and pools.

Diet: South American lungfishes eat insects; insect larvae (LAR-vee), or insects in the early stage of growth; other invertebrates (in-VER-teh-brehts), or animals without a backbone; fishes; and algae (AL-gee), which are tiny, plantlike growths that live in water. They do not feed during estivation (es-tuh-VAY-shun), or the period of in activity during dry spells.

Behavior and reproduction: South American lungfishes swim by slow, wavy movement or by "crawling" on their pectoral and pelvic fins. Because their gill surfaces are not large enough to meet their oxygen needs, lungfishes drown if they stay underwater. For estivation, they dig burrows by biting the soil and expelling, or forcing, mud through their gill openings. They then breathe the oxygen in the hole. Spawning usually occurs during the wet season. Fertilization is external. Males guard and fan, or use their fins to move water over, newly hatched young to clean them and give them oxygen.

South American lungfishes and people: South American lungfishes usually are not eaten. They often are displayed in aquariums.

Conservation status: South American lungfishes are not threatened or endangered. ∎