|Family Ecology, Behavior Breeding Interactions Lore & Notes Status Pictures|
In this section I group together what are usually considered the more dangerous snakes, those that are highly poisonous and large ones that kill by squeezing their prey. Few short-term visitors to Costa Rica encounter a poisonous snake because most are well camouflaged, secretive in their habits, or nocturnal and, therefore, they are really outside the scope of this book. However, most people are extremely leery of snakes and want to be well-informed about them, just in case.
Vipers, of the Family Viperidae, comprise most of the New World's poisonous snakes. Among all snakes they have the most highly developed venom injection mechanisms: long, hollow fangs that inject poison into prey when they bite. The venom is sometimes neurotoxic; that is it interferes with nerve function, causing paralysis of the limbs and then respiratory failure. Other venoms cause haemorrhaging both at the site of the bite and then internally, leading to cardiovascular shock and death. (The answer to the question of why venomous snakes are not harmed by their own venom is that they are immune.) Typically, vipers coil prior to striking. They vary considerably in size, shape, colour pattern, and lifestyle. Many of the viperids are referred to as pit-vipers because they have heat sensitive "pits," or depressions, between their nostrils and eyes that are sensory organs. Pit-vipers occur from southern Canada to Argentina, as well as in the Old World. The familiar venomous snakes of North America are pit vipers - rattlesnakes, copperheads, water moccasins, as are most of Costa Rica's poisonous snakes.
The deadly Fer-de-lance is abundant in Costa Rica in lowland wet areas and along watercourses in drier areas. Most are shorter than the maximum length of 2.5m (8 ft). As their name suggests, they resemble a lance or spear, being slender snakes with triangular heads. Palm vipers, such as the Eyelash Vipers, are common arboreal snakes of lowland areas. There are several species, alI small (as long as 1 m, or 3 ft, but most are only haIf that long) with prehensile tails and large wide heads. Their colour schemes vary extensively. The Tropical Rattler occurs in Costa Rica mostly in the drier north-western part of the country. Reaching a length of 1.5m (8 ft), it is a heavy-bodied snake with a slender neck and broad, triangular head. The rattles consist of loosely-interlocking segments of a horn-like material at the base of the tail. A new segment is added each time the snake sheds its skin. Bushmaster, the largest venomous snakes of the Neotropics, inhabit lowland wet areas, such as the Osa Peninsula and La Selva area. They are the giants of the pit-vipers, slender, large-headed snakes reaching lengths of 2.5 to 3.5 m (9 to 12 ft).
Coral Snakes. The Family Elapidae contains what are regarded as the world's deadliest snakes, the Old World cobras and mambas. In the WesternHemisphere, the group is represented by the coral snakes - small, often quite gaily attired in bands of red, yellow and black, and, unfortunately, possessed of a very powerful neurotoxic venom. Four coral snake species occur in Costa Rica, one of which is a fairly common terrestrial animal of moist lowland areas. Coral snakes rarely grow longer than a meter (3 ft).
Boas. The Family Boidae, members of which kill by constriction, encompasses about 80 species that are distributed throughout the world's tropical and subtropical regions. They include the Old World pythons and the New World's boas and anacondas, the pythons and anacondas being the world's largest snakes. Four boa species, but not the Anaconda, call Costa Rica home. The Boa Constrictor, one of the four, occurs over a wide range of habitat types, wet and dry, from sea level up to about 1000m (3300 ft). This boa reaches lengths of about 6m (19 ft), but typical specimens are only 1.5 to 2.Sm (S to 8 ft) long. They have shiny, smooth scales and a back pattern of dark, squarish shapes that provides good camouflage against an array of backgrounds. Within a species male and female snakes usually look alike, although in many there are minor differences between the sexes in traits such as colour patterns or the sizes of their scales.