Caecilian (Gymnophiona or Apoda)

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Caecilian (Gymnophiona or Apoda)

Conservation Status:
Depending on the species, either Vulnerable, Not Threatened or Least Concern.

Range/Distribution:


Caecilians are divided into six families:
Beaked Caecilians (Rhinatrematidae) - 2 genera, 9 species
Fish Caecilians (Ichthyophiidae) - 2 genera, 39 species
Indian Caecilians (Uraeotyphlidae) - 1 genus, 5 species
Tropical Caecilians (Scolecomorphidae) - 2 genera, 6 species
Aquatic Caecilians (Typhlonectidae) - 5 genera, 13 species
Common Caecilians (Caeciliidae) - 26 genera, 99 species

Identifying Characteristics: Caecilians completely lack limbs, making the smaller species resemble worms, while the larger species resemble snakes. The tail is short or absent, and the cloaca is near the end of the body. Their skin is smooth and usually dark-matte, but some species have colorful skins.
Size: Body lengths vary depending on species and age from 4.3 in (11 cm) to 4 ft 11 in (1.5 m).
Habitat: Tropical forests and grasslands and on stream banks. Land-dwelling tailless caecilians live in loose, moist, soil rich in decayed plant matter and leaf litter. They are often found under rocks, logs, and waste material.
Food: The diet of caecilians is not well-known, though it seems to mostly consist of insects and invertebrates found in the habitat of the respective species. The stomach contents of 14 specimens of Afrocaecilia taitana consisted of mostly undefinable organic material and plant remains. Where identifiable remains were most abundant, they were found to be termite heads. While it was suggested that the undefinable organic material shows that the caecilians eat detritus, others believe these are in fact the remains of earthworms. Caecilians in captivity can be easily fed with earthworms, and worms are also common in the habitat of many caecilian species. Aquatic caecilians can often be fed on fish.
Reproduction: For some species the young caecilians are already metamorphosed when they hatch; others hatch as larvae. The larvae are not fully aquatic, but spend the daytime in the soil near the water. 75% of the species are viviparous, meaning that they give birth to already developed offspring. The fetus is fed inside the female with cells of the oviduct, which they eat with special scraping teeth. The egg laying species Boulengerula taitanus feeds its young by developing an outer layer of skin, high in fat and other nutrients, which the young peel off with similar teeth. This allows them to grow by up to ten times their own weight in a week. The skin is consumed every three days, the time it takes for a new layer to grow, and the young have only been observed to eat it at night. It was previously thought that the juveniles subsisted on a liquid secretion from their mother. Some larvae, such as those of Typhlonectes, are born with enormous external gills which are shed almost immediately. Ichthyophis is oviparous and known to show maternal care, with the mother guarding the eggs until they hatch.
Other Information: Little is known of the evolutionary history of the caecilians, which have left almost no fossil record. What few fossils exist suggest that they have changed little in millions of years. The earliest fossil known comes the Jurassic period. This primitive genus, Eocaecilia, had small legs and well-developed eyes.