Anatomy of Venomous Snakes

The anatomy of venomous snakes is widely varied, but some aspects are universal. All snaked have similar venom delivering apparatus systems comprised of venom glands, a duct with an accessory gland and fangs for venom delivery.

Rattle snake venom apparatus. Proteroglyph venom apparatus are similar to the one depicted here, except that the fang is fixed in proteroglyphs. Image taken from Rattlesnake Venoms, copyright 1982. Marcel Decker Inc.

The venom glands are where venom is produced and they consist of three major cell types: basal cells, conical mitochondria-rich cells, and secretory cells, which produce the venom. Venom production appears to be regulated by the gland itself and is independent of neural control. Kochva determined that the gland contains some baro-sensitive (pressure sensitive) cells, and that fluid pressure inside the gland was the main determinant in rate for venom production. Not all components of venom are produced at the same rate. Venom that is fresh has a different composition than venom that has been allowed to mature because some components of the venom are not present until the venom is several days old.

Venom is carried from the gland to the fang by a duct that flows through an accessory gland. The accessory gland was noted by Mitchell to prevent wasteful flow of the secretions. This gland lacks smooth muscle and is strictly regulated by striated muscle. Implications are that the accessory gland is under voluntary control and that snakes can and do control the amount of venom that is released during a bite. The secretions from the accessory gland are generally non-toxic and mucous-like, but often these secretions mix with the venom and act as an activating complex, which increases the potency of the venom.

Fangs are cone-shaped and tapered and are usually curved and are essentially hollow venom delivering tubes. They can be replaced if lost or damaged and some species even have reserve fangs that remain in a suspended, immature state until stimulated to develop. The fang is the site of envenomation. Some snakes have the ability to spit venom.

A textbook diagram of a rattlesnake fang. Image taken from Rattlesnake Venoms, copyright 1982. Marcel Decker Inc.

 

Keep in mind that there are many anatomical differences between the different kinds of venomous snakes. Crotalids have pits, sea snakes have flattened tails, some snakes have bony ridges over their eyes, etc. There are even differences in the types of venom delivery systems. For a good overview of venom delivery system anatomy that is concise and well written, consult the book Snake Venoms and Envenomation by Sherman A. Minton. There are also many fine web sites you may wish to visit by going to the links page.

 

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