Caecilians are also found in Indonesia, Sri Lanka, the Philippines, and the Seychelles. Of the three amphibian orders, only caecilians have an axial musculature in which all the hypaxial components, excluding the subvertebral musculature, form an outer muscular sheath. Gymnophiona is the group of amphibians that includes the legless caecilians and all amphibians more closely related to them than to frogs or salamanders (the "stem-caecilians"). The derived reproductive modes oviparity with direct development and viviparity evolved independently in the three amphibian groups, i.e. Snakes and turtles and frogs, oh my! Caecilians have long, limbless, cylindrical bodies that abruptly end behind the cloaca or short tail. Because of their relatively hidden existence, caecilians are unfamiliar to the layperson and are not usually considered in discussions about amphibians. The body is cylindrical dark brown or bluish black in colour. Los gimnofiones (Gymnophiona, qu'en griegu significa "culiebra desnuda") o ápodos (Moteya), conocíos vulgarmente como cecilias o cecílidos, son un clado d'anfibios carauterizaos principalmente por presentar un aspeutu vermiforme, tentáculos olfativos y una ausencia d'estremidáes, cintura coxal y cintura escapular. Several species of caecilians in the South American genus Caecilia exceed 1 metre (about 3.3 feet) in total length; the largest known caecilian is C. thompsoni, at 152 cm (about 60 inches). On the Seychelles there are three genera native to the islands, although caecilians are not found on any other islands in the Indian Ocean. [9] The Late Triassic stem-caecilian Chinlestegophis from the Chinle Formation of Colorado bolsters the proposed pre-Triassic origin of Lissamphibia suggested by molecular clocks by filling a gap in the fossil record of early caecilians and suggesting that groups of stereospondyls, including Metoposauridae, are closely related to caecilians. Though we edit our accounts for accuracy, we cannot guarantee all information in those accounts. Some caecilians deposit eggs on land, and in different species these hatch as larvae or small adults. Male caecilians with their phallodeum, an intromittent organ, generate and deliver sperm into the cloaca of female caecilians. This is achieved by means of the phallodeum, a copulatory organ in males that is modified from the cloacal wall. Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox. Oviparity with biphasic life-cycle is the ancestral mode of reproduction in the Lissamphibia. The name derives from the Greek words γυμνος (gymnos, naked) and οφις (ophis, snake), as the caecilians were originally thought to be related to snakes. These adaptations make it possible for the caecilian to feed, reproduce, and avoid enemies within their subterranean realm. Certain fish adapted to these changing conditions by gradually developing limbs to crawl with and lungs to breathe with. Gymnophiona, also called Apoda, one of the three major extant orders of the class Amphibia. The breeding period of some Asiatic ichthyophiids seems to be aseasonal or at least without seasonal constraints. Herpelidae (African Caecilians) ... Reproduction and Life Cycle. [8] Divergent origins of caecilians and other extant amphibians may help explain the slight discrepancy between fossil dates for the origins of modern amphibia, which suggest Permian origins, and the earlier dates, in the Carboniferous, predicted by some molecular clock studies of DNA sequences. The derived reproductive modes oviparity with direct development and viviparity evolved independently in the three amphibian groups, i.e.