The Amphiumidae are a family of just one genus and three species. Their common name of "Congo eels", though they are neither eels nor from the Congo, at least gives some idea of their appearance: an elongated cylindrical body [Grzimek] with small, almost vestigial arms and legs. Their heads are pointed and the eyes small, black and covered by skin. The primary senses seem to be touch and smell. All three are confined to SE USA.
Amphiumids undergo an incomplete metamorphosis from the larval stage, but are not usually considered neotenic. For example, the skin undergoes complete metamorphosis, but adults like larvae lack eyelids [Grzimek]. Other characteristics are as follows: extremely smooth skin; torso cylindrical; costal grooves conspicuous; lungs are present; retains four gill arches, but lacks external gills; open spiracle on each side of the body between third and fourth gill arch; long trachea to the lungs is supported by cartilage; tongue absent; very large red blood corpuscles (in fact the largest known in any vertebrate); 63 amphicoelous (hollowed out on both sides) vertebrae, of which only the front ones are connected to ribs. The skull structure resembles that of the Salamandridae [Grzimek]. The larvae are born with external gills but lose them within 2-3 months [Indiviglio].
Fred Cagle conducted an interesting survey and observation of a population of Amphiuma tridactylium (the Three-Toed Amphiuma) in a large park in Tulane in 1948. The park was bordered on three sides by residential housing but on the fourth by a levee of the Mississipi River, and included a golf course, a lagoon and drainage ditches 2-12" deep. The water table remained near the soil surface all year round. Cagle and his team found it comparatively easy to collect amphiumas whenever heavy rains caused brief flooding on the golf course. When this occurred, the amphiumas would leave their hiding places and be quite active in the temporary pools, during which time their dark bodies were easily visible against the grass. Otherwise they would largely remain in their underground burrows, apparently moving up and down in accordance with the water table. When water was present in the ditches and lower areas, daily activity tended to peak between 10 and 12pm. The amphiumas were not active if the water temperature fell below 9 deg C. Cagle did note also some characteristics of the population that seemed to be at variance with surrounding populations, namely the generally smaller size of the animals and the two year reproductive cycle of the females which he attributed to restrictions in feeding. The males were sexually active from mid-January to mid-May, and a driving rain appeared to be a stimulus to courtship. During this act a sperm flake would be transferred to the female cloaca. The females would lay between 42 and 131 eggs in the burrow between May and June. (Indiviglio notes that the incubation of eggs takes about five months). The young would remain in the burrows until brought upwards by the water table. Females became sexually mature at about 33cm in length.
Indiviglio makes the observation that in the wild, the waters that are home to amphiumas can be quite acidic in their pH, although he does not insist upon this as a precondition for their captive care. Conant and Collins also point out that the amount of "muck" (and mud) that often form part of their habitat.
Amphiumids do not seem to be regularly kept in captivity, even within the US. This is partly because of their needs (Indiviglio recommends a deep tank and subdued lighting) and partly because they are noted for having a poor disposition, lightning quick reactions (in contrast with most caudates) and willingness to make extremely severe bites on human flesh. However, in an age when lizard keepers are willing to tackle much larger (and sometimes equally truculent) creatures such as Green Iguanas, Tegus and various monitors, it seems strange that caudatophiles are not more interested in keeping and breeding amphiumids. There are still many observations that could be made on these unusual amphibians, especially as nowadays we have the help of webcams and associated software to help us watch our charges through the night hours.
Husbandry notes: of the books I have read, Indiviglio seems to have the most comprehensive notes on keeping. Eric Rundquist suggests feeding minnows and/or mice 2-3 times a month: I would qualify this by saying that the mice might be rather fatty as a staple of the diet and would probably not be suitable for A. pholeter anyway. As with any captive animal, the ideal is to see what the creature eats in the wild and try to reproduce this or to try to find a suitable equivalent.
A. means, Two-Toed Amphiuma | A. pholeter, One-Toed Amphiuma | A. tridactylum, Three-Toed Amphiuma |
Bibliography - Amphiumidae
There seems to be no one single work (at least outside academic circles) dealing with the family Amphiumidae in its entirety. However, most books on newts and salamanders, or on herpetology in general, seem to at least carry a page or two on them and their captive husbandry.
Newts & Salamanders - a complete pet owner's manual, Frank Indiviglio, Barrons 1997. An excellent introduction to the subject of the care and husbandry of newts and salamanders, giving a general natural history, general requirements in captivity and finally a very wide selection of popular species accounts (including Sirens, Amphiumas and the Hellbender) and their needs. The author also notes the importance of caudates as a sort of environmental barometer in the wild and encourages the reader to think ethically and ecologically. Although I had never heard of Frank Indiviglio before he writes well and succinctly. I absolutely recommend this book.
Observations on a population of the salamander Amphiuma tridactylium, Fred R Cagle, Ecology Vol 29/4 October 1948. Interesting study of a large population of A. tridactylium in a Tulane park.
A Field Guide to Reptiles and Amphibians of Eastern and Central North America, R Conant and J T Collins, Peterson Field Guides, Houghton Mifflin, Boston/New York 1998. Gives details of all three species.
Animal Life Encyclopedia Volume 5: Fishes and Amphibia, Grzimek,1975 provided details of the general appearance of the species.
Reptile and Amphibian Care, Eric M Rundquist, TFH, 1994. Useful overall guide to herpetological husbandry, although worth checking against other sources. Little specific on amphiumas other than the guidelines mentioned above.
Keeping and Breeding Amphibians, Chris Mattison, Blandford Press.
The Proper Care of Amphibians, John Coborn, TFH, 1992.
Links
Index of newt- and salamander-related articles from herpetological magazines.
Tree of Life has a very useful entry on the Family Salamandridae, including the anatomical characteristics.
AmphibiaWeb is a useful source for species lists and has information on some if not most of the species.
LivingUnderworld.org also has a well-organised and informative set of pages on the Salamandridae.
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