Snake defense

Gehibach, F. R., Watkins, J. F., and Reno H. W., 1968, Blind snake defensive behaviour elicited by ant attacks, BioScience 18 784-785. 

Experimental data suggest that VN stimuli might also play a relevant role in prey-predator interactions by mediating affective responses to prey or predator chemical cues. For instance, one of the preferred prey for the snake Thamnophis sirtalis is earthworms. Halpern (1988) demonstrated that earthworm wash constitutes a VN stimulus that is rewarding for these snakes. On the other hand, it has been shown that rats display defensive reactions to a collar that has been worn by a cat, even if they have no previous experience with cats. For these defensive behavioral responses to occur, direct contact with the collar is needed (Dielenberg and McGregor 2001). 

FIGURE 7.4 A female brown tree snake discharges cloacal defense secretion. (From Greene and Mason, 2000.)... 

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. 

Since predators of snakes (and humans) have to deal with snake venoms as defenses, they are included here, even though they serve in predation. Snake venoms are primarily enzymes (proteins), especially of the phospholipase A2 type, which breaks down cell membrane phospholipids hydrolytically. Other snake venoms such as cobrotoxin contain peptides with 60-70 amino acid residues. Pharmacologically, they have neurotoxic, cytotoxic, anticoagulant, and other effects. The neurotoxins, in turn, can have pre- or postsynaptic effects. Snake venoms with both neurotoxic and hemolytic effects on the heart are known as cardiotoxins. Cytotoxins attach to the cells of blood vessels and cause hemorrhage. Snake venom factors may stimulate or inhibit blood clotting. Finally, platelet-active factors can contribute to hemorrhage. 

Siberian chipmunk Eutamias sibiricus asiaticus Carcass Snake Self-defense Kobayashi and Watanabe, 1986... 

Weldon, P. J. and Burghardt, G. M. (1979). The ophiophage defensive response in crotaline snakes extension to new tzxz. Journal of Chemical Ecology 5,141-151. 

Animal toxins are roughly divided into venoms and poisons. Venoms are offensive, used in the quest for food. Snakes produce toxins that can immobilize or kill prey for food. The venom of spiders paralyzes insects to allow the spider to feed on the victim s body fluids. While the venoms may also be used defensively, their primary purpose is in the quest for food. Most venom is delivered from the mouth, as in snakes and spiders, but there are exceptions like the scorpion that uses its tail. 

Snakes occupy a unique place in our collective imagination. The primary function of snake venom is to immobilize or kill prey for food. A secondary function of the venom is defensive or protective, but clearly snakes are not capable of eating large animals, such as humans. Often venomous snakes will strike but not release venom, which conserves a valuable resource. Approximately 400 of the more than 3500 species of snake are sufficiently venomous to be a threat to humans and other large animals. 

Defense Antibodies, toxins from snake venom (these toxins may themselves be enzymes)... 

Toxic proteins Serve as a defense for the plant or animal Snake venoms ... 

Hermes-Lima, M., and K.B. Storey (1993). Antioxidant defenses in the tolerance of freezing and anoxia by garter snakes. Am. J. Physiol. 265 R646 R652. 

Approximately 30-40% of snake species produce some type of buccal toxins or venom. The major adaptive functions of venoms and buccal toxins in snakes have been associated with food acquisition, defense, and predigestion of prey items. Venomous species possess specialized structures (venom glands or Duvernoy s glands), which produce venom or toxins and enlarged teeth or fangs, which inject or introduce the venom into the prey item. Venom contains enzymes and proteins that break down cellular structures and interferes with critical functions such... 

Hutchinson DA, Savitzky AH, Mori A, Meinwald J, Schroeder FC. Maternal provisioning of sequestered defensive steroids by the Asian snake Rhabdophis tigrinus. Chemoecology 2008 18(3) 181-90. 

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