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Caecilian Ecology
Generally speaking, caecilians are extremely secretive
and difficult to find due to their burrowing lifestyle. A great number
of the known caecilian species are known from only a single specimen.
Even the most experienced of researchers can spend many months looking
but fail to find them. The aquatic and semi-aquatic species of the
family Typhlonectidae are often easy enough to find; they are regularly
caught in fine-mesh fishing nets by fishermen in South America.
Terrestrial species can sometimes be found in large numbers after heavy
rains or floods have saturated the soil and forced them to the surface.
Otherwise, to find them by flipping rocks, turning logs, or digging in
presumed habitat is a matter of chance. As a result, we know very little
about caecilians. This page will endeavor to explain a little of what we
do know about them so far.
Caecilians are predominantly tropical and can be found in the tropics of
the Americas, Africa, India, The Seychelles Archipelago, and Southeast
Asia. A single species, Chthonerpeton indistinctum, is also found
in temperate Argentina and Uruguay (Fig 1).
The soil ecosystem has been referred to as "ecology's
subterranean blind spot" for good reason. Being dense and opaque, it
presents substantial obstacles to the ecologist, yet soil forms the
basis for vegetation and as a result, forms the basis for the ecosystem
above. The extent to which caecilians shape the subterranean ecosystem
and as a result, shape the ecosystem above, is still unknown.
Diet
Caecilians are carnivorous and while the natural diets of most
species have not been studied, the studies that have been conducted
suggest that at least most terrestrial caecilians are probably
generalist predators upon earthworms and other soft-bodied invertebrate
prey they find underground or in leaf litter. Some caecilians such as
Siphonops also appear to prey heavily upon ants or termites and live
in close association with their nests. In addition, beetles, small
frogs, lizards, and small blind snakes have also been found in the
stomachs of some caecilians. Aquatic caecilians seem to eat soft-bodied
aquatic invertebrates as well as carrion and readily accept most
animal-based foods in captivity.
Predators
Despite the poison glands present in their skin, some animals
do eat caecilians. Coral snakes in particular have been known to
regurgitate caecilians when captured and so are presumed to be one of
the main natural predators. The red-tailed pipe snake has been seen
eating an Ichthyophis species and a Scolecomorphus kirkii
has been found in the gut of a burrowing asp. It is likely that other
ground-dwelling snakes also frequently prey upon them. In addition,
chickens, pigs, some shorebirds, and tenrecs have all been documented to
eat caecilians at one time or another.
References:
Cogger, H.G., & R.G. Zweifel. 2003. Encyclopedia of
Reptiles and
Amphibians: A Comprehensive Illustrated Guide by International
Experts. Fog City
Press, San Francisco.
Gaborieau, O. & J.G. Measey. 2004. Termitivore or Detritivore? A
Quantitative
Investigation into the Diet of the East African Caecilian
Boulengerula taitanus
(Amphibia; Gymnophiona, Caecilidae). Animal Biology 54: 45-56.
Gower, D.J., Rasmussen, J.B., Loader, S.P., & M. Wilkinson. 2004. The
Caecilian
Amphibian Scolecomorphus kirkii as Prey of the Burrowing Asp
Atractaspis aterrima
Gunther: Trophic Relationship of Fossorial Vertebrates. African
Journal of Ecology
42: 83.
Kupfer, A., Gower, D.J., & H. Werner. 2003. Field Observations on the
Predation of the
Caecilian Amphibian, genus Ichthyophis (Fitzinger 1826), by
the Red-tailed Pipe-
Snake Cylindrophis ruffus (Laurenti 1768).
Amphibia-Reptilia 24: 212-215.
Measey, J.G., Gower, D.J., Oomen, V.O., & M. Wilkinson. 2004. A
Subterranean
Generalist Predator: Diet of the Soil Dwelling Caecilian
Gegeneophis ramaswamii
(Amphibia; Gymnophiona, Caecilidae) in Southern India. C.R.
Biologies 327: 65-76.
Pillai, R.S. & M.S. Ravichandran. 1999. Gymnophiona of India: A
Taxonomic Study.
Rec. Zoological Survey India, Occasional Paper No. 172: 1-126.
Pough, F.H., R.M. Andrews, J.E. Cadle, M.L. Crump, A.H. Savitzky, K.D.
Wells. 1998.
Herpetology. Prentice Hall Press, New Jersey.
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