Coelacanths and Lungfishes: Sarcopterygii

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COELACANTHS AND LUNGFISHES: Sarcopterygii

COELACANTH (Latimeria chalumnae): SPECIES ACCOUNTS
SOUTH AMERICAN LUNGFISH (Lepidosiren paradoxa): SPECIES ACCOUNTS

PHYSICAL CHARACTERISTICS

Coelacanths (SEE-lah-kanths) and lungfishes have rounded, fleshy fins. They are closely related to four-footed land vertebrates (VER-teh-brehts), or animals with a backbone.

GEOGRAPHIC RANGE

Coelacanths live on both sides of the Indian Ocean. Lungfishes live in South America, Africa, and Australia.

HABITAT

Coelacanths live in caves deep in the ocean. Lungfishes live in slow-moving rivers, swamps, lakes, floodplains, and ponds.

DIET

Coelacanths are opportunistic (ah-per-too-NIS-tik) bottom feeders, meaning that they take advantage of whatever is available at the bottom of their water habitat. Lungfishes are predators (PREH-duh-ters), or animals that hunt and kill other animals for food.

BEHAVIOR AND REPRODUCTION

Coelacanths give birth to live young. Lungfishes reproduce by external fertilization (FUR-teh-lih-zay-shun), meaning that eggs, or female reproductive cells, and sperm, or male reproductive cells, unite outside the female's body.

COELOCANTHS, LUNGFISHES, AND PEOPLE

Coelacanths are valued mainly for research. Lungfishes are common in aquariums.

AMAZING DISCOVERY

The December 1938 find of a living coelacanth caused disbelief and created one of the greatest biological sensations of the twentieth century. Finding a living coelacanth, so similar to the fossil (FAH-suhl) specimens left in rocks more than seventy-five million years ago, was as inconceivable as meeting a living dinosaur. The living coelacanths are often celebrated as the most unusual case and important example of animal evolution.

CONSERVATION STATUS

The World Conservation Union (IUCN) lists one species of coelacanths as Critically Endangered, meaning that it faces an extremely high risk of extinction in the wild in the near future. Lungfishes are not threatened or endangered.

COELACANTH (Latimeria chalumnae): SPECIES ACCOUNTS

Physical characteristics: Coelacanths have fleshy fins. Instead ofbeing made up of individual bones, or vertebrae (ver-teh-BREE), the backbone is a stiff tube. Coelacanths are bluish gray with white mark-ings. They weigh 110–198 pounds (50–90 kilograms). Female coela-canths can be as long as 6 feet (1.9 meters) and males as long as 5 feet (1.50 meters).

Geographic range: Coelacanths live on both sides of the Indian Ocean.

Habitat: Coelacanths live in caves in tropical oceans below 328 feet (100 meters), in steep, sloping areas. At night they move up the slope to feed.

Diet: Coelacanths eat whatever they find as they drift in the current. Because they can lift the upper jaw as well as move the lower jaw, coelacanths can open their mouths quite far to suck prey from crevices.

Behavior and reproduction: While swimming, coelacanths move their pectoral (PECK-ter-uhl) and pelvic fins the way most four-footed animals move their legs. The pectoral fins are the front pair, and the pelvic fins are the rear pair. Coelacanths give birth to live young, but scientists do not know how they what sort of mating takes place. The gestation (je-STAY-shun) period, or time the young develops inside the female, is about thirteen months. Scientists believe females become mature for the first time when they are more than twenty years old.

Coelacanths and people: Coelacanths are valued for the information they can provide about evolution.

Conservation status: The World Conservation Union (IUCN) lists one species of coelacanth as Critically Endangered, meaning that it faces an extremely high risk of extinction in the wild in the near future. ∎

SOUTH AMERICAN LUNGFISH (Lepidosiren paradoxa): SPECIES ACCOUNTS

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.

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. ∎