Some aspects of the biology and development of Ichthyophis glutinosus (Amphibia: Gymnophiona)

Specimens of Ichthyophis glutinosus hatched in the laboratory were studied over a three‐year period. Larval mortality during the early period of development was very high, with only three out of an initial number of 19 larvae surviving to the present. The aquatic larvae change gradually into terrestrial burrowing forms within 48–50 weeks after hatching. The larval condition is characterized morphologically by a more rounded head with sense organs, prominent eyes and a tail fin, whereas the post‐metamorphic form has a more pointed head, reduced eyes, tentacles, nuchal collars and yellow lateral stripes. Examination by light microscopy shows the larval skin to be thinner than adult skin and lacking a keratinized stratum corneum and calcified scales. Leydig cells found only in larval skin elaborate a secretion which is a periodate reactive acidic mucosubstance with a protein component. They decrease in number and disappear at metamorphosis. Length and weight increases of the larva arc gradual but after metamorphosis arc marked by weight increases being greater than increase in length. Metamorphosis itself is gradual, spread over an appreciably long period, and is not as dramatic as in anurans.