The two-toed amphiuma (''Amphiuma means'') is an aquatic salamander widely distributed in the

southeastern United States The Southeastern United States, also known as the American Southeast or simply the Southeast, is a geographical List of regions in the United States, region of the United States located in the eastern portion of the Southern United States and t ...

. It is commonly, but incorrectly, called "congo snake", "

conger eel ''Conger'' ( ) is a genus of marine congrid eels. It includes some of the largest types of eels, ranging up to or more in length, in the case of the European conger. Large congers have often been observed by divers during the day in parts of ...

" or the "blind eel".

Description

Two-toed amphiumas are the most prominent in the Amphiumidae family and the longest salamander species in the United States, that can grow from in mass and from in length.Caudata Culture Species Entry – Amphiuma
Caudata.org. Retrieved on 2013-01-03.Deyle, Anna C. (2011
Population Genetics of ''Amphiuma means'' and ''Siren lacertina'' in Central Florida
M.S. Thesis, University of South Florida They have four vestigial legs that end in two toes; the number of toes is one of the primary differences between ''Amphiuma means'' and its relatives, the one-toed and three-toed amphiumas. Additional genetic studies have been conducted on the three species; genetic distance estimates suggest that there is high levels of similarity between two-toed amphiumas and three-toed amphiumas, and much greater dissimilarity between the one-toed amphiuma and the two-toed amphiuma. The head is pointed and wedge-shaped, and the eyes are small. Adults retain a single gill slit on each side of the head. They are black, dark grey or dark brown in color. Two-toed amphiumas tend to be unicolored. Their dark dorsum contrasts with their slightly lighter ventrum.

Distribution and habitat

Amphiumas live in areas of shallow, heavily vegetated water in swamps,

bayou In usage in the Southern United States, a bayou () is a body of water typically found in a flat, low-lying area. It may refer to an extremely slow-moving stream, river (often with a poorly defined shoreline), marshy lake, wetland, or creek. They ...

lake A lake is often a naturally occurring, relatively large and fixed body of water on or near the Earth's surface. It is localized in a basin or interconnected basins surrounded by dry land. Lakes lie completely on land and are separate from ...

s, and

pond A pond is a small, still, land-based body of water formed by pooling inside a depression (geology), depression, either naturally or artificiality, artificially. A pond is smaller than a lake and there are no official criteria distinguishing ...

s, as well as

wet prairie Prairies are ecosystems considered part of the temperate grasslands, savannas, and shrublands biome by ecologists, based on similar temperate climates, moderate rainfall, and a composition of grasses, herbs, and shrubs, rather than trees, as the ...

s. They tend to be found below the fall line but occasionally in low sandy pine hills. It has been found that their microhabitats largely coincide with high prey availability. They require a habitat with light soil, so they can burrow in it. Their range includes southeastern

Virginia Virginia, officially the Commonwealth of Virginia, is a U.S. state, state in the Southeastern United States, Southeastern and Mid-Atlantic (United States), Mid-Atlantic regions of the United States between the East Coast of the United States ...

, eastern

North Carolina North Carolina ( ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, South Carolina to the south, Georgia (U.S. stat ...

South Carolina South Carolina ( ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders North Carolina to the north and northeast, the Atlantic Ocean to the southeast, and Georgia (U.S. state), Georg ...

, southern

Georgia Georgia most commonly refers to: * Georgia (country), a country in the South Caucasus * Georgia (U.S. state), a state in the southeastern United States Georgia may also refer to: People and fictional characters * Georgia (name), a list of pe ...

and

Alabama Alabama ( ) is a U.S. state, state in the Southeastern United States, Southeastern and Deep South, Deep Southern regions of the United States. It borders Tennessee to the north, Georgia (U.S. state), Georgia to the east, Florida and the Gu ...

Florida Florida ( ; ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders the Gulf of Mexico to the west, Alabama to the northwest, Georgia (U.S. state), Georgia to the north, the Atlantic ...

, south

Mississippi Mississippi ( ) is a U.S. state, state in the Southeastern United States, Southeastern and Deep South regions of the United States. It borders Tennessee to the north, Alabama to the east, the Gulf of Mexico to the south, Louisiana to the s ...

Arkansas Arkansas ( ) is a landlocked state in the West South Central region of the Southern United States. It borders Missouri to the north, Tennessee and Mississippi to the east, Louisiana to the south, Texas to the southwest, and Oklahoma ...

Louisiana Louisiana ( ; ; ) is a state in the Deep South and South Central regions of the United States. It borders Texas to the west, Arkansas to the north, and Mississippi to the east. Of the 50 U.S. states, it ranks 31st in area and 25 ...

, and southeastern

Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...

Behavior

Two-toed amphiumas are nocturnal, and are often difficult to handle because of their slippery skins. They may leave water temporarily if weather is wet enough. They dig burrows in muddy stream bottoms, or may invade the burrows of other aquatic creatures. They are primarily found in the littoral zones where fish and crayfish are most abundant and vegetation is floating, on logs, or submerged. They are harmless to humans when left alone, but, when disturbed, they can deliver a tough bite, which may lead to a severe infection. ''A. means'' gives a clear whistle when disturbed. It has been studied that two-toed amphiumas utilize acoustic signals during social interactions for communications at short distances, as the species did not express these acoustics when housed individually. These acoustic signals can be described as "clicks". There are three discernable clicks produced, ranging in frequencies.

Breeding

Amphiumas breed from June to July in

and northern

. Females lay about 200 eggs in a damp cavity beneath debris, close to standing water, and they remain coiled around them during incubation (which lasts around five months). These eggs are laid in strings.Gunzburger, M., S. (2003). Evaluation of the Hatching Trigger and Larval Ecology of the Salamander ''Amphiuma means''. Herpetologica, 59(4), 459–468. https://doi.org/10.1655/02-82 Hatchlings are about long with three pairs of light-colored external gills soon lost after hatching. In some conditions offspring can exhibit direct development and hatch without external gills. In a series of three studies conducted in northern Florida, two-toed amphiuma eggs hatched in response to inundation with water, can stand without feeding for 125 days by using resources from their yolk reserves, and the eggs can retain a period of no growth and still survive after 110 days on a moist substrate. A study depicted seasonal lipid storage increases in males' testicular region and females' liver.

Diet

Two-toed amphiumas feed on small

fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...

tadpole A tadpole or polliwog (also spelled pollywog) is the Larva, larval stage in the biological life cycle of an amphibian. Most tadpoles are fully Aquatic animal, aquatic, though some species of amphibians have tadpoles that are terrestrial animal, ...

crawfish Crayfish are freshwater crustaceans belonging to the infraorder Astacidea, which also contains lobsters. Taxonomically, they are members of the superfamilies Astacoidea and Parastacoidea. They breathe through feather-like gills. Some spe ...

insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...

s and insect

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

e. They are also recorded to prey on

reptile Reptiles, as commonly defined, are a group of tetrapods with an ectothermic metabolism and Amniotic egg, amniotic development. Living traditional reptiles comprise four Order (biology), orders: Testudines, Crocodilia, Squamata, and Rhynchocepha ...

s and

amphibian Amphibians are ectothermic, anamniote, anamniotic, tetrapod, four-limbed vertebrate animals that constitute the class (biology), class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all Tetrapod, tetrapods, but excl ...

s such as southern cricket frogs,

southern leopard frog ''Lithobates sphenocephalus'' or ''Rana sphenocephala'', commonly known as the southern leopard frog, is a medium-sized anuran in the family Ranidae (the true frogs). The southern leopard frog is one of the 36 species currently or formerly classi ...

greater siren The greater siren (''Siren lacertina'') is an amphibian and one of the five members of the genus '' Siren''. The largest of the sirens and one of the largest amphibians in North America, the greater siren resides in the coastal plains of the sout ...

s, peninsula newts, water snakes of the genus ''

Nerodia ''Nerodia'' is a genus of nonvenomous colubrid snakes commonly referred to as water snakes due to their aquatic behavior. The genus includes nine species, all native to North America. Five of the species have recognized subspecies. Descript ...

'' and small

mud turtle ''Kinosternon'' is a genus of small aquatic turtles from the Americas known commonly as mud turtles. Geographic range They are found in the United States, Mexico, Central America, and South America. The greatest species richness is in Mexico, ...

s. When feeding, they have two types of suction feeding: buccal expansion with no forward movement of the head for small prey and buccal expansion with a rapid strike, sharp teeth, and rapid twisting to subdue larger prey. Their hunting behavior is not thoroughly understood, but they are believed to forage actively for food and to wait under debris and in burrows for prey to approach them. They likely detect prey through olfaction.

References

{{Taxonbar, from=Q243813 Salamandroidea Extant Pleistocene first appearances Fauna of the Southeastern United States Amphibians of the United States Amphibians described in 1821