Poisonous Snakes of Kansas

by Robert F. Clarke

The poison of venomous snakes is not only a defensive mechanism, but also a highly efficient food-getting device. Whereas some of the snakes strike and hold the prey within their jaws until the poison has rendered it helpless, others only strike and follow the trail to where the victim falls.

In feeding, the snake does not chew its food, but swallows it whole. The jaws are wonderfully adapted for this purpose, having the bones on each side of the jaws attached to their mates on the other side by an elastic ligament, and the upper and lower jaws also joined by such an attachment. This allows the jaws to be spread apart and lowered, making an opening capable of taking in a food item actually larger in diameter than the snake! The teeth of both the upper and lower jaws are recurved, pointing inward, and as each section of the jaw can work independently, one side secures its grip while the other side moves forward. Thus, the snake actually crawls around its food.

ABUNDANCE: The non-poisonous snakes far outnumber the poisonous kinds, both in number of species and individuals. In the United States, there are approximately 95 species of non-poisonous snakes and only 19 species of poisonous ones, including 15 rattlesnakes, one copperhead, one cottonmouth, and two coral snakes. In Kansas, there are six species of poisonous snakes (two should hardly be counted) and 34 species of non-poisonous snakes. Many of the non-poisonous species are common and widespread. It is far more probable that any snake seen is non-poisonous than poisonous.

SNAKE BITE: Venom is secreted from glands within the head, on each side behind the eyes, causing the swollen appearance of the head in this region. The venom travels through ducts to each of the two fangs. The fangs are enlarged teeth in the front of the upper jaw. They are hollow, with one end connected to the poison duct and the other end having an opening on the front edge near the tip. The fangs are also fastened to a moveable bone, which enables the fangs to be folded back against the upper jaw when the mouth is shut and erected and directed forward when the mouth is opened to strike. The power of a strike imbeds the fangs into the skin of the victim, and muscles force venom from the glands through the duct and hollow fang and out of the opening at the tip. The venom causes a breakdown of the red blood corpuscles and walls of blood vessels. It also has an effect upon the nervous system. Some snakes have venom which is much more destructive to the nervous system. The pit vipers have venom which is more hemotoxic (destructive to blood), whereas the coral snake, which belongs to the cobra group, has a venom which is neurotoxic (destructive to nerves).

The venom is yellowish and somewhat “thicker” than water. The amount of poison ejected at any one strike varies from a part of a drop to 2 cubic centimeters, depending upon size and kind of snake, and time elapsed since last venom ejection. Various factors influence the amount of venom which is injected into the victim, i.e., smaller snakes have smaller fangs and less venom; strikes through clothing or footwear are less effective.

It has been estimated that there are fewer than 50 deaths due to snake bite in the United States in a year; most of these bites result from imprudent handling of venomous serpents. There has been no survey of snakebite in Kansas, but few deaths are reported annually. At times several years have elapsed without any deaths being reported. Most victims are less than 20 years of age and most bites occur on the hands, feet, arms, or legs.

It should be stressed that poisonous snakes cannot be made harmless by removing the fangs. The poison glands and ducts remain and other teeth can still scratch the skin, allowing entrance of the venom. Also, “reserve” fangs are normally present. These are immature fangs lying along the upper jaw bone. At intervals a reserve fang grows down beside a fang which has been used for some time. The old fang is shed and a new sharp “hypodermic needle” is in position. Thus, snakes are sometimes found with three or four fangs.

DUCT POISON GLAND FANG SHEATH TONGUE SKULLS NON-POISONOUS POISONOUS REPLACEMENT FANGS

Snake venom is used to manufacture antivenin, which is injected into snakebite victims to help counteract the effects of the poison. The venom is injected in graduated doses into horses, which build up an immunity to the venom. Blood is withdrawn from the horse and the serum is processed to produce antivenin.