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The Rubber Eel, Typhlonectes natans



Many hobbyists have probably seen these fascinating creatures in pet stores under the label "Sicilian Worm" or "Rubber Eel." Don't bother asking the clerk what they are, chances are he or she probably won't know. They might tell you they're worms from Sicily or that they are rubbery eels (I've heard both responses). But it's not his fault he doesn't know. There is almost no literature on them from which to learn. Just what are these guys and why is there so much confusion surrounding them?

Neither worms nor eels, caecilians (not Sicilians) are members of an ancient family of amphibians. These unique animals went underground long before the dinosaurs appeared. They are rarely seen in the wild because, with the exception of Typhlonectes natans, they spend almost their entire lives underground. T. natans is one of the only ones that spends a great deal of time in an aquatic environment, and is the focus of this article. This species is native to Columbia (South America), and grows to 18 to 22" in length. It is a dark grey- black in color and closely resembles its relative T compressicauda in appearance (T. compressicauda is brownish with a slightly thicker body). But what do these animals offer to the hobbyist?

Both aquarists and herpers alike can find enjoyment keeping caecilians. Relatively hardy creatures, caecilians will eat almost anything that can't get away from them. In the wild, they feed upon invertebrates such as insects, spiders,and worms. They are not above taking pieces of fish or even sinking pellets, for that matter. I feed mine pellets, earthworms, and even small fresh shrimp. Other good foods are fresh or frozen silversides and live tubifex or waxworms. Do not use live feeder fish because your caecilian will not even be able to find them. They are nearly blind and find their food by taste and smell, which means that they can be kept in aquaria with small, active fish that can easily evade them. Sick or dying fish or small fish that like to sit on the bottom (i.e. kuhli loaches) may become a meal, though. I've seen these guys chase earthworms for quite a ways beneath the substrate and emerge victorious, as their chemical senses are highly developed.

An interesting note is that not all caecilians even possess eyes, some of the subterranean species being an example where nature provided them a unique adaptation. In these animals the eye muscles have developed into sensory probes that wave about like antennae picking up chemical cues. All caecilians, however, are constructed for digging about; therefor the hobbyist should provide substrate that is not too course or sharp, since the animal could easily injure itself. Caves or other objects should also be provided for them to hide in or under.

Other conditions should include clean, well-aerated water. While T. natans can and occasionally does breath air, most of the respiration takes place through its skin. Good water quality should be maintained to keep stress to a minimum, even though it is a fairly hardy animal. It has been my own experience that a specimen of this species is more likely to escape from the aquarium then to expire there. For this reason, an aquarium housing a caecilian should have a well-fitting cover.

Although it is difficult (if not impossible) to sex caecilians, they can be bred in an aquarium. I would suggest keeping a group of them in an aquarium with clean, soft water at about 74 to 78F. The pH isn't too critical, but you might try slightly acidic (about 6.5) water softened by peat. The female will swell noticeably when fertilization has occured and will give birth to one or more live young, which will look like smaller versions of their parents. The young can eat the same foods as the adults, though on a smaller scale, of course. Since caecilians seem to demand a fairly good price, breeding this bizarre species might be a worthwhile pursuit for some hobbyists to try. If you are successful, share your experience with other hobbyists.

There is much that is still unknown about these creatures, which is reflected by the lack of informative literature about them. I would invite you to give these inoffensive fellows a place in your aquaria. Their shy, comical manner can delight both experienced and inexperienced herpers and aquarists alike.

by Kent Turner

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