Chemical map of skin secretions in old-world snakes

Abstract

Skin secretions of snakes are complex mixtures consisting mainly of various non-polar, fat-soluble compounds with different purposes, incl. water permeability, social communication, and intra- and interspecific recognition. Comprehensive understanding of snake skin secretion composition is important for studying some of their key physiological or behavioural processes. In the current study, we describe skin secretion composition of 13 Old-World snake species using samples from shed skins, as well as alive or dead individuals. All samples were from adult snakes and were extracted by means of short immersion (for live individuals) or soaking for 24 h in n-hexane (for shed skins and dead individuals). We used a standard coupled gas chromatography-mass spectrometry (GC-MS) for the analysis of the samples and detected 88 compounds in the skin secretions, with alkanes being the most common type. The identified compounds are likely to play a role in skin water permeability, host defence and chemical communication. While some compounds, such as alkanes, were common for most species, others, such as fatty acids and some ketones, displayed greater variability. We determined that the two sample extraction methods often produced different results for the same species, so any comparisons should me made with caution. The established differences between samples from live individuals and shed skins can lead to important conclusions regarding either methodologies used, as well as the physiology of the analyzed species. We discuss interspecific qualitative variations in skin secretions and compare our results with the available published data, providing a thorough literature review on skin secretions regarding 10 different genera.