Tick
Description: Round body from size of pinhead to 2.5 cent meters. Has 8 legs and sucking mouth parts. There are 850 species worldwide.
Habitat: Mainly in forests and grasslands. Also in urban areas and farmlands.
Distribution: Worldwide.
CHAPTER 4
POISONOUS SNAKES AND LIZARDS
If you fear snakes, it is probably because you are unfamiliar with them or you have wrong information about them. There is no need for you to fear snakes if you know—
• Their habits.
• How to identify the dangerous kinds.
• Precautions to take to prevent snakebite.
• What actions to take in case of snakebite
For a man wearing shoes and trousers and living in a camp, the danger of being bitten by a poisonous snake is small compared to the hazards of malaria, cholera, dysentery, or other diseases.
Nearly all snakes avoid man if possible. Reportedly, however, a few—the king cobra of Southeast Asia, the bushmaster and tropical rattlesnake of South America, and the mamba of Africa—sometimes aggressively attack man, but even these snakes do so only occasionally. Most snakes get out of the way and are seldom seen.
WAYS TO AVOID SNAKEBITE
Snakes are widely distributed. They are found in all tropical, subtropical, and most temperate regions. Some species of snakes have specialized glands that contain a toxic venom and long hollow fangs to inject their venom.
Poisonous Snakes of the Americas
• American Copperhead (Agkistrodon contortrix)
• Bushmaster (Lachesis mutus)
• Coral snake (Micrurus fulvius)
• Cottonmouth (Agkistrodon piscivorus)
• Fer-de-lance (Bothrops atrox)
• Rattlesnake (Crotalus species)
Poisonous Snakes of Europe
• Common adder (Vipers berus)
• Pallas’ viper (Agkistrodon halys)
Poisonous Snakes of Africa and Asia
• Boomslang (Dispholidus typus)
• Cobra (Naja species)
• Gaboon viper (Bitis gabonica)
• Green tree pit viper (Trimeresurus gramineus)
• Habu pit viper (Trimeresurus flavoviridis)
• Krait (Bungarus caeruleus)
• Malayan pit viper (Callaselasma rhodostoma)
• Mamba (Dendraspis species)
• Puff adder (Bitis arietans)
• Rhinoceros viper (Bitis nasicornis)
• Russell’s viper (Vipera russellii)
• Sand viper (Cerastes vipera)
• Saw-scaled viper (Echis carinatus)
• Wagler’s pit viper (Trimeresurus wagleri)
Poisonous Snakes of Australasia
• Death adder (Acanthophis antarcticus)
• Taipan (Oxyuranus scutellatus)
• Tiger snake (Notechis scutatus)
• Yellow-bellied sea snake (Pelamis platurus)
The polar regions are free of snakes due to their inhospitable environments. Other areas considered to be free of poisonous snakes are New Zealand, Cuba, Haiti, Jamaica, Puerto Rico, Ireland, Polynesia, and Hawaii.
There are no infallible rules for expedient identification of poisonous snakes in the field, because the guidelines all require close observation or manipulation of the snake’s body. The best strategy is to leave all snakes alone. Where snakes are plentiful and poisonous species are present, the risk of their bites negates their food value.
Although venomous snakes use their venom to secure food, they also use it for self-defense. Human accidents occur when you don’t see or hear the snake, when you step on them, or when you walk too close to them.
Follow these simple rules to reduce the chance of accidental snakebite:
• Don’t sleep next to brush, tall grass, large boulders, or trees. They provide hiding places for snakes. Place your sleeping bag in a clearing. Use mosquito netting tucked well under the bag. This netting should provide a good barrier.
• Don’t put your hands into dark places, such as rock crevices, heavy brush, or hollow logs, without first investigating.
• Don’t step over a fallen tree. Step on the log and look to see if there is a snake resting on the other side.
• Don’t walk through heavy brush or tall grass without looking down. Look where you are walking.
• Don’t pick up any snake unless you are absolutely positive it is not venomous.
• Don’t pick up freshly killed snakes without first severing the head.
• The nervous system may still be active and a dead snake can deliver a bite.
SNAKE GROUPS
Snakes dangerous to man usually fall into two groups: proteroglypha and solenoglypha. Their fangs and their venom best describe these two groups (Table 4-1).
Fangs
The proteroglypha have, in front of the upper jaw and preceding the ordinary teeth, permanently erect fangs. These fangs are called fixed fangs.
Table 4-1: Snake group characteristics
Group
Fang Type
Venom Type
Proteroglypha
Fixed
Usually dominant neurotoxic
Solenoglypha
Folded
Usually dominant hemotoxic
The solenoglypha have erectile fangs; that is, fangs they can raise to an erect position. These fangs are called folded fangs.
Venom
The fixed-fang snakes (proteroglypha) usually have neurotoxic venoms. These venoms affect the nervous system, making the victim unable to breathe.
The folded-fang snakes (solenoglypha) usually have hemotoxic venoms, These venoms affect the circulatory system, destroying blood cells, damaging skin tissues, and causing internal hemorrhaging.
Remember, however, that most poisonous snakes have both neurotoxic and hemotoxic venom. Usually one type of venom in the snake is dominant and the other is weak.
Poisonous Versus Nonpoisonous Snakes
No single characteristic distinguishes a poisonous snake from a harmless one except the presence of poison fangs and glands. Only in dead specimens can you determine the presence of these fangs and glands without danger.
DESCRIPTIONS OF POISONOUS SNAKES
There are many different poisonous snakes throughout the world. It is unlikely you will see many except in a zoo. This manual describes only a few poisonous snakes. You should, however, be able to spot a poisonous snake if you–
• Learn about the two groups of snakes and the families in which they fall (Table 4-2).
• Examine the pictures and read the descriptions of snakes in this appendix.
Viperidae
The viperidae or true vipers usually have thick bodies and heads that are much wider than their necks (Figure 4-1). However, there are many different sizes, markings, and colorations.
This snake group has developed a highly sophisticated means for delivering venom. They have long, hollow fangs that perform like hypodermic needles. They deliver their venom deep into the wound.
The fangs of this group of snakes are movable. These snakes fold their fangs into the roof of their mouths. When they strike, their fangs come forward, stabbing the victim. The snake controls the movement of its fangs; fang movement is not automatic. The venom is usually hemotoxic. There are, however, several species that have large quantities of neurotoxic elements, thus making them even more dangerous. The vipers are responsible for many human fatalities around the world.