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Amphiumas: Amphiumidae

Physical Characteristics

Amphiumas (AM-fee-YOO-muhs) are very long, medium-sized to very large salamanders that look like snakes with four very short legs. These animals are dark reddish brown to gray or black on top. The belly is a lighter shade than the back or almost as dark. Adult amphiumas reach a length of 13 to 46 inches (33 to 117 centimeters), depending on the species. The legs usually are less than 0.4 inch (1 centimeter) long, and there are one to three toes on each foot.

Amphiumas have a pointed head, but the snout is somewhat flattened in two species. There are teeth on the jaw bones. Amphiumas have no eyelids and have one gill slit on each side of the body. Gills are organs for obtaining oxygen from water. Unlike the bushy, outside gills of other salamanders, the gills of amphiumas are inside their bodies, just behind the head. Gill slits are openings from the gills to the outside of the body. Gill arches support the gills inside the body.

Adult amphiumas have glands in their skin that ooze out slippery mucus. An amphiuma's tail is flat from side to side and makes up 20 to 25 percent of the total body length. A lateral (LAT-uhr-uhl) line, a system of organs that help some animals sense movement in the water, is present on the body and head of amphiumas. The bodies of these animals have fifty-seven to sixty grooves along the sides, each of which indicates a vertebra (VER-teh-bruh), or one of the bones that make up the spinal column. The vertebrae (VER-teh-bree, the plural of vertebra) are curved in on each end like the inside of a bowl. A few vertebrae near the front of amphiumas have ribs connected to them.

Amphiumas are the longest and largest salamanders in the United States. Even though local people call amphiumas congo eels, lamper eels, ditch eels, lampreys, and congo snakes, these salamanders are amphibians, not fish like eels and lampreys and not reptiles like snakes. Amphibians (am-FIB-ee-uhns) are vertebrates (VER-teh-brehts), or animals with a backbone, that have moist, smooth skin; are cold-blooded, meaning their body temperature is the same as the temperature of their surroundings; and, in most instances, have a two-stage life cycle.

Amphiumas that have gone through metamorphosis keep some features of larvae: a lack of eyelids and tongue and the presence of four gill arches with a single opening to the outside between the third and fourth arches rather than a slit for each gill. Larvae (LAR-vee) are animals in an early stage that change body form in a process called metamorphosis (MEH-tuh-MORE-feh-sis) before becoming adults. Amphiumas have lungs, but they also can breath through their throat and skin. When young amphiumas hatch, they keep their gills for a few days. Hatchlings are a little more than 2 inches (5 centimeters) long. Amphiumas that have just gone through metamorphosis may be as short as 2.5 inches (6 centimeters). Adults reach a length of 46 inches (117 centimeters).

Additional topics

Animal Life ResourceAmphibiansAmphiumas: Amphiumidae - Physical Characteristics, Behavior And Reproduction, Amphiumas And People, Three-toed Amphiuma (amphiuma Tridactylum): Species Account - GEOGRAPHIC RANGE, HABITAT, DIET, CONSERVATION STATUS