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The ringed caecilian, Siphonops annulatus, has one of the widest distributions of any terrestrial caecilian. Found at altitudes less than 800 m. asl across South American on the eastern side of the Andes from tropical northern Columbia, Venezuela, across the Guyanas, Peru, Ecuador, most of Brazil, Bolivia, Paraguay and into Northern Argentina, some suggest that S. annulatus may represent more than one species; more taxonomic work is needed.
Measuring 280-450 mm in total length, S. annulatus has a blue grey body with the edges of the grooves on each body segment colored white, which give the animal its regular white rings. It has small eyes with vision limited to dark/light detection, a thick head, and non-tapering body. Granular glands in its skin produce mucus that incude toxins, small amounts of which can paralyze frogs and rodents, thought perhaps used for predator avoidance. Recent analyzes find some components of the mucus have antiparasitic activity that might be commercially effective against protozoa and trypanosomes causing diseases such as leishmaniasis and Chagas disease.
A subterranean species, the ringed caecilian burrows to about 20cm (9 in) in rich moist soil in a broad diversity of habitats: forested, open, savannah, and also tolerant of disturbed areas such as gardens, plantations and farm areas, even in semiarid areas. Adults feed on underground invertebrates. The females lay transparent eggs, which hatch into a litter of between 5-16 altricial miniature adults, about 40mm long.
Hatchlings feed by crawling across the mother’s body, scraping off the outer layer of her maternally modified lipid-rich skin (distinctly lighter in color than non-breeding females) with specialized fetal teeth. Offspring feed together in short frenzied bouts. This maternal dermophagy has also been observed in the African caecilian Boulenerula taitanus, which diverged from S. annulatus 100 million years ago and shared fetal teeth morphologies indicate this behavior may be a very old form of parental care ancestral to all caecilians. Hatchlings also eat a clear liquid the mother exudes from her cloacal opening; this behavior is not known from any other amphibians and the contents of the liquid have not been analyzed.