Amphiuma is a genus of aquatic salamanders found in the United States, and it’s the only living genus within the family Amphiumidae.
These creatures are often called Amphiumas, Conger Eels, or Congo Snakes, but these names can be misleading. Amphiumas are not fish, reptiles, or from the Congo; they are actually amphibians.
They have a lot of DNA, around 25 times more than humans.
What Is the Taxonomy of Amphiumas?
Amphiumas are related to the families Rhyacotritonidae (torrent salamanders) and Plethodontidae (lungless salamanders).
They have a particularly close relationship with the Plethodontidae family.
The earliest known member of the Amphiuma family is the Proamphiuma from the Cretaceous period.
It looks similar to modern species, except for its simpler vertebral structures.
What Do Amphiumas Look Like?
Amphiumas have long, grey-black bodies and very small, vestigial legs. They can be up to 46 in (116 cm) long, but their legs are only about 0.79 in (2 cm) long.
Because of this, they are often mistaken for eels or snakes. They also don’t have eyelids or a tongue.
Amphiumas have a special feature called a lateral line on the sides of their bodies, which helps them detect movement when hunting.
How Do Amphiumas Reproduce?
Females lay their eggs in wet mud and then coil around them for about five months until they hatch.
The young Amphiumas have external gills, but these disappear after around four months as their lungs begin to work.
They keep one pair of gill slits with functioning internal gills, so their metamorphosis is incomplete.
What Are the Different Species of Amphiumas?
There are three living species of Amphiumas, and they can be identified by the number of toes they have:
- Three-toed Amphiuma (Amphiuma tridactylum) – found in the southeastern United States
- Two-toed Amphiuma (Amphiuma means) – also found in the southeastern United States
- One-toed Amphiuma (Amphiuma pholeter) – found in central Florida, the Florida panhandle, extreme southern Georgia, and southern Alabama
There are also two extinct species, Amphiuma jepseni (from the Paleocene of Wyoming) and Amphiuma antica (from the Miocene of Texas).
Where Do Amphiumas Live?
Amphiumas are found in the southeastern part of the United States.
They share much of their range with Sirens, another type of salamander, although they are not closely related.
In the past, Amphiumas had a wider range across North America, reaching all the way to Wyoming.
What Is the Behavior of Amphiumas?
During the day, Amphiumas hide in vegetation, and at night they become active hunters.
Their diet includes frogs, snakes, fish, crustaceans, insects, and even other amphiumas.
They are similar to Axolotls in their hunting and eating habits, which involve sucking in their food with vacuum force.
They can become aggressive if provoked and are rarely found on land.
Females court males before mating. When a pair forms, they wrap their bodies around each other, and the male transfers a spermatophore directly into the female’s cloaca (cloacal apposition).
What Are the Food Habits of Amphiumas?
Amphiumas eat a variety of foods, including annelids, vegetables, arachnids, mollusks, and larvae.
They prefer to eat crawfish and will pass on smaller ones to eat larger ones. This helps them save energy by not chasing less calorie-dense prey.
In captivity, Amphiumas become more active when food is introduced into their habitat.
Anatomy of Amphiumas
Jaw Muscles
Amphiumas have strong jaw muscles that help them catch and hold prey, as well as create suction to bring in food.
They have two types of suction feeding: stationary (with little to no body movement) and strike (with rapid body movement).
Lungs
Amphiumas have long lungs that extend over half of their body length.
They have dense capillary networks and large surface areas, which suggest they use their entire lung for respiration in water or on land.
They mainly breathe through their lungs, even though they live in water.
Respiration
Amphiumas have a unique two-cycle pressure-induced process for breathing that involves both their buccal cavity/nares (mouth and nostril) region and their lungs.
They exhale twice before inhaling, using a negative pressure gradient in their lungs to take in the air.
Sexual Dimorphism
Male Amphiumas usually have larger bodies and longer heads than females, which might indicate male-male combat within the population.
However, there are no other physical signs of combat, such as horns or spines.
Some populations don’t show these traits, and the males and females look similar.