Meeting Abstract
The subterranean brahminy blindsnake (Ramphotyphlops braminus) is among the smallest vertebrate animals on Earth. Among reptiles, snakes have very small eyes, but the fossorial R. braminus has extremely small eyes that are located underneath the skin and scales, and completely invisible from the exterior. This study is part of a comprehensive analysis of what may be the simplest nervous system in any terrestrial vertebrate on the planet, the goals of which are (1) to assess the cellular architecture of the R. braminus eye, (2) to produce an atlas of the R. braminus brain and determine the central targets of retinal projection, (3) to determine whether the R. braminus eye responds physiologically to light, and (4) to determine how light exposure may modify R. braminus behavior. Scanning electron microscopy and visible light microscopy revealed an eye-like structure underneath the skin and scales of the head, the cellular architecture of which was examined by histological and immunofluorescence approaches. Electroretinography showed that the snakes respond to light using their apparently rudimentary eyes. Finally, a series of behavioral experiments revealed that these snakes may not respond to the appearance of shadows from above, but may navigate with the aid of light (via negative phototaxis). This work provides new understanding of the anatomy, physiology and behavior of one of the world’s smallest vertebrate animals, provides a better concept of the fundamental components of central neuroanatomy required for vertebrate animals to perform complex behavior, and provides new insight into the evolutionary adaptations of micro-vertebrate life.
