Caecillian care and breeding

The care and captive breeding of the Caecilian
(Typhlonectes natans)
Copyright: Richard W Parkinson & the Herpetological Bulletin
8th March 2004
 
Introduction
   
Caecilians (Apoda) are the often overlooked third order of amphibians and are not thought to be closely-related to either Anurans or Urodelans. Despite the existence of over 160 species occurring throughout the tropics (excluding Australasia and Madagascar), relatively little is known about them.
 
pic1The earliest known fossil caecilian is Eocaecilia micropodia, which is dated to the early Jurassic Period approximately 240 million years ago. Eocaecilia micropodia still possessed small but well developed legs like modern amphiumas and sirens. The wormlike appearance and generally subterranean habits of caecilians has often led to their dismissal as primitive and uninteresting. This view-point is erroneous. Far from being primitive, caecilians are highly adapted to their lifestyle. Typhlonectes natans are minimalist organisms having dispensed with tail, limbs, one lung and functioning eyes. Animals which live in underground burrows or the turbid depths of South American rivers, however, have no use for these organs.
 
Instead of sight, caecilians have a pair of organs known as the tentacles situated in pits between the eye and nostril. The tentacles are connected to both the optic nerves (and muscles) and the olfactory system. How this hybrid sense (sight, taste and smell combined) functions is unknown. That this sense does function is undeniable. I can testify from personal observation how rapidly caecilians locate and consume food. The research of Himstedt & Simon (1995) clearly demonstrates how efficient caecilians are at foraging for food using the tentacle organ by locating food items faster than newts in experiments. They are the only vertebrate animals known to possess motile sub-ocular tentacles. Caecilians have poor hearing but, like other amphibians and fish, have a well developed lateral line system.
 

Many caecilians have no larval stage and, while some lay eggs, many including Typhlonectes natans give birth to live young after a long pregnancy. Unlike any other amphibian (or reptile) this is a true pregnancy in which the membranous gills of the embryo functions like the placenta in mammals, so that the mother can supply the embryo with oxygen. The embryo consumes nutrients secreted by the uterine walls using specialized teeth for the purpose.

 
 
             
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