Unraveling parental care in caecilians: nutritional and toxinological implications in Siphonops annulatus

Abstract

Caecilians (order Gymnophiona) are apodan, serpentiform amphibians, distributed in most of the tropical regions of the planet. Due to the generally fossorial habit and the low diversity of species, the caecilians constitute the least known group of tetrapods in all biological aspects. As in other amphibians, their skin has a multifunctional role, participating in several vital activities. Their skin is rich in glands that secrete a variety of substances, acting directly on reproduction, water economy, gas exchange, and production of compounds used against predators and microorganisms. The research group of the Cell Biology Laboratory of Instituto Butantan, participating of an international team, discovered a peculiar phenomenon related to parental care, which was widely disseminated by the international midia. This finding, published in 2006 (Nature, 440, 926-929), was considered by Marvalee Wake as "perhaps the most dramatic new discovery in caecilian biology" (Wake, 2012). This discovery demonstrated that the young oviparous caecilians, during parental care, feed exclusively on the mother's skin, phenomenon that is known as skin feeding (or dermatophagy). Although described more than a decade ago, the biology, morphology, biochemistry and molecular biology related to this phenomenon remain little elucidated. For example, it is possible that the composition of secretions and the morphology of the cutaneous glands change during parental care. It is also possible that the secretions contain molecules that are important for the nutrition and immunity of the young, similar to the breast milk in mammals. This project, therefore, aims at the study of the oviparous caecilian Siphonops annulatus during and outside the period of parental care. It proposes the use of this species as a model for the study of skin feeding, through the use of an integrative approach. (AU)