Skin pheromones snake

The blind snake Leptotyphlops dulcis is a specialized burrower that feeds on termites and ant brood. It follows the ant pheromone trails to find its prey (Section 12.1). when attacked by ants, this snake tilts its scales individually so that the skin appears silvery. While it writhes, it covers itself with feces and a clear viscous fluid, discharged from the anus. It may also assume a stationary coiled position. when it resumes searching and feeding, it is no longer attacked by ants. The effect lasts from 3 to 30 minutes (Gehlbach etal., 1968). Here a predatory species protects itself from the defensive actions of its prey. 

The red-sided garter snake pheromone components were isolated by hexane extraction of the skin lipids of sacrificed snakes. Female snakes yielded more total lipid than males (38.4 versus 8.4mg snake-1)80 Initial fractionation on an activity III alumina column gave a fraction (eluted with 98 2, hexanes ethyl ether) that was attractive to courting males. NMR and infrared (IR) spectra of this fraction were suggestive of the presence of methyl ketones, straight chain alkyl lipid subunits, and Z-alkenes. GC—MS analysis, including extensive consideration of the fragmentation of the electron impact MS data, led to the identification of a family of relatively nonvolatile (C29—C37) lipid methyl ketones. Specifically, the individual components of a mixture of saturated and monounsaturated methyl ketones 18—30 were identified. 

Snakes, as a group, are visually cryptic and auditorially impoverished. Therefore, it is probable that chemical cues are quite important in mate location. The utilization of pheromone trails in the reproductive activity of snakes has been examined to some extent in temperate zone colubrids. In these snakes, sexual behavior occurs primarily in the spring. Males leave the hibernacula first and remain in the vicinity to court the females when they emerge. At this time, female snakes leave trails for the males to follow. The pheromone involved is likely the same lipoprotein (vitellogenin) which the females produce in the liver and secrete through the skin to stimulate male courtship activity (Garstka and Crews, 1981, this volume), although the only evidence for this is that the sexual pheromone trails are also produced by skin secretions and, like a lipoprotein, are non-volatile and persistent (Ford and Low, 1984). 

Further, exogenous estrogen injection will induce pheromone production in females and males (Kubie et al., 1978). Unlike females, estrogen-injected male garter snakes are never courted by males. However, serum from estrogen-injected males and females, when spread on the backs of control males, will elicit courtship from sexually active males (Crews, 1976). These observations suggest that the skin in the male and female differ in their transport of the attractiveness pheromone. 

Garstka, W., and Crews, D., 1981, Female sex pheromone in the skin and circulation of a garter snake. Science, 214 681. 

Because we used methylene chloride as a solvent to extract pheromone-containing substances from shed snake skins, we hypothesized that resulting extracts were lipoidal in nature. And because our behavioral bioassays indicated that neonatal rattlesnakes responded differentially to extracts from conspecific and heterospecific sources, we hypothesized that there might be detectable differences between the chemical structures of such extracts. Additionally, knowledge of the extract s chemical structure might provide insight into their biological roles. 

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