Throughout Central America, venomous snakes are found widespread. For this report I will be discussing the different venomous snakes that are found in the Costa Rica region and the different types of habitats that they inhabit. I will also cover the different types of prey that these snakes hunt, and the types of venom that the different species have. Also I will also be touching on the different anti-venoms that are currently under practice and use for the snakebites, and also proper steps to take if one is unfortunately bitten.
In Costa Rica, snakes make up almost half of all the reptile species in the country. There are 135 species of snakes, and only 17 are known to be venomous in Costa Rica. These 17 species of venomous snakes are the only ones that are known to be clinically important throughout the Costa Rica region. Other species of snakes may contain traces of venom such as the brown vine snake, however the amount of venom that is carried and injected by this snake is as toxic as a bee sting or an ant bite. The two different families of venomous snakes found in Costa Rica region are the coral snake family (Elapidae), and the pit-viper family (Crotalidae). There are 5 species of Elapids and 12 species of Crotalids that are found in Costa Rica. I will first discuss the Crotalidae family of snakes found in Costa Rica.
The family Crotalidae is comprised of the coral snake species. There are four known different coral snake species in Costa Rica and they include Allen's coral snake (Micrurus alleni), Central American coral snake (Micrurus nigrocinctus), bicolored coral snake (Micrurus multifasciatus), and Micrurus clarki. All of these coral snakes belong to the genera Micrurus. The other genera, Micruroides are not found in Central America. All of these coral snakes are highly venomous, and brightly colored with bright bands of red, black, and yellow or white. These snakes have small heads and blunt tails which allows them to maneuver easily around the leaf litter and rocky regions. The two most common species of coral snakes that you may be likely to see is the Allen's coral snake and the American coral snake. The bicolored coral snake is uncommon, and the Micrurus clarki is extremely rare. Allen's coral snake is a tricolored, black, yellow or white, and red ringed snake. The black of the head projects behind over the adjacent yellow band as a narrow marking at its mid-dorsum region. Allen's coral snake can be distinguished from the bicolored coral snake because the bicolored has more than 40 black bands, and Allen's has 26 or fewer. Allen's coral snake is found in deep forests under ground cover where it may be seen during daylight hours, as well as evening hours. It usually occurs in wet lowland forests and along riverbanks. Its diet consists of lizards, skinks, snakes, mammals, and possibly eels (Russell pp.1475). Its range is mostly along the eastern coast of Costa Rica.
The bicolored coral snake, which is also known as the coralilla or rabo de aji snake, is a long slender bicolored coral snake with red and black rings; the black rings are usually wider than the red however. Juveniles of the species seem to be more brightly colored than adults and some adults may exhibit black or white except for the endpoint of the tail. The bicolored coral snake is usually found in moist and lowland rain forests between 100 and 1700 m. This snake is often commonly found around human habitations (Russell pp.1476).
Another coral snake member, the Central American coral snake is probably the most common coral snake that is found in Central America. In general these snakes are tricolored, however in some of the six sub-species of this species they may be bicolored. The snake is made of yellow, black and some red bands. There may be anywhere from ten to 29 black rings, and three to eight black bands on the tail. This snake is found up to 1500 m in lowland forest but is also known from near the seashore. Its diet consists of snakes, lizards, skinks and birds.
In general the identification of coral snakes in Costa Rica is often difficult because of many variations and sub-species of each species. An often-used saying when dealing with coral snakes is "red on yellow, kill a fellow; red on black that's OK jack." This however is not an applicable guideline to follow when dealing with Costa Rica's coral snakes. If a coral snake is approached by something, their defense display is that they flatten their bodies and snap back and forth while alternately hiding then swinging their heads side to side and coiling and waving their tails. Another important note with coral snakes is that when they bite their prey, they don't have the same type of fangs as the Crotalids. Their fangs are fixed in their upper jaw, and can't be folded back. When they bite their prey, they have to almost use a chewing motion to inject appropriate amounts of venom to subdue their prey.
The second type of venomous snakes found in Costa Rica consists of the Crotalids. There are 13 known Crotalids that inhabit Costa Rica. The Crotalids are members of the pit viper family. They are named pit viper because of a 'pit' located behind their eyes that senses heat from prey. Their wedge shaped heads are easily distinguishable, along with their elliptical vertical pupils and rough-scaled bodies. The pit vipers have solenoglyph fangs that are mounted on the maxillary bones in such a way that they can be rotated and folded against the roof of the mouth. The two most abundant species are the eyelash palm-pit viper (Bothriechis shclegelii), and the Fer de lance (Bothrops asper). Other fairly common species include one species of the hognosed pitviper (Porthidium nasutum), the Neotropical rattlesnake (Crotalus durissus), and the jumping pitviper (Atropoides nummifer). Some fairly uncommon snakes that you may happen to luckily encounter (or unluckily) is the bushmaster (Lachesis muta), and the Godman's montane pitviper (Cerrophidion godmani). There are seven other species of Crotalids that are found in Costa Rica and they include other species of forest pitvipers, other hognosed pitvipers, and also other species of jumping pitvipers.
The eyelash palm pitviper is a relatively slender pitviper that usually doesn't reach lengths over 820 m. This snake can have various ground colors, usually golden yellow, olive green or gray-green. Its name eyelash palm pitviper comes from the spine like processes above the eyes. It's range is quite extensive throughout all of central America, however in Costa Rica it would be likely to be found in tropical and montane wet forests up to 1500 m. Its diet consists of lizards, birds, reptiles and amphibians.
The second type of snake that is commonly seen in Costa Rica is the fer-de-lance also known as the lancehead, and terciopelo by Costa Ricans. The fer-de-lance is one of the world's most venomous snakes. It can reach lengths up to 3 meters. Its body color varies, with olive green, gray, tan, brown or rust blotches, which are usually separated by light edging. The fer-de-lance inhabits a variety of habitats. It can be found in overgrown fields and river courses in drier lowland regions, as well as montane, deciduous wet forests. It is often found near human cultivation as well. It is generally a nocturnal snake, however if stepped on or encountered during the day, they are quick to strike. As juveniles, the fer-de-lance is an arboreal snake that feed on lizards and frogs, which they attract with a yellow-tipped tail. As adults they come down and rest in loose leave litter on the forest floor.
Another member of the Crotalids is the Neotropical rattlesnake. This is the only known rattlesnake snake that inhabits Central America as well as Costa Rica. They can be identified by their dark paravertebral blotches, and the rattle. The body color varies from brown to greenish, while the venter is white or cream. These snakes are usually found at elevations less than 1000 m, however specimens have been found up to 2500 m. They are usually found in dry areas, scrub woodlands, grasslands. They are rare in rain forests. The Neotropical rattlesnake eats anything from mammals to amphibians to birds.
Another pit viper that I will discuss is the bushmaster, which is the largest viper in the world. It is found in the Atlantic lowlands of Costa Rica and in the pacific lowlands of Costa Rica as well. All though this snake is extremely rare to encounter, it is somewhat abundant in the Costa Rica region. The head of the snake is broad and distinct from the neck. The eyes are relatively small with vertically elliptical pupils (as in all pit vipers). The body is more or less cylindrical, and the tail is tapered with spiny scales on the underside. The body color varies from tan to brownish colors. Scientists discovered that bushmasters that are found in the pacific lowlands of Costa Rica tend to be aggressive any time they are disturbed. This snake is extremely dangerous to humans because of its large size, large fangs and extremely large reservoir of venom. A case report was done by Miguel Tanus Jorge, about a field scientist who was bitten by a bushmaster. According to the descriptions the initial bite only connected with one fang on the index finger. As the subject was rushed to medical care, within ten minutes he was feeling the effects of the venom. The subject luckily lived, however he had to stay in the hospital for weeks recovering.
Snake venom can be summarized as a complex mixture, which contains proteins, amines, carbohydrates, organic salts and acids, and possibly other unidentified substances. Most snake venom is a neurotoxin, which disrupts the nervous system of the prey, however the other type attacks the muscular and respiratory system of the prey. For coral snakes, studies have shown that coral snake venom caused respiratory paralysis in cats prior to cardiac failure (Russell pp.1484). Attempts to find an appropriate anti-venom to most coral snake bites found that a certain anti-venom given against M. frontalis was the most suited for use as a coral snake antivenin, giving the most neutralizing and precipitating antibodies. Due to coral snakes having rear fangs, it reduces their ability to bite large objects. To protect against the possibility of being bitten by a coral snake, one might wear thick hiking boots that would deter the fangs from reaching your skin. Most coral snake bites occur when someone deliberately picks up the snake or mis-identifies the snake for another species and is bitten in the hand. In Costa Rica depending on where you are, seeking medical attention may take hours. Studies have shown that with coral snake bites a smart thing to do is to gently massage the area where the victim was bit to hopefully push out venom from the bite wound.
Venom of pitvipers varies extensively from species to species. Snakebites by pitvipers are much more common than being bitten from a coral snake. The most venomous of all pitvipers in Costa Rica is the venom of the fer-de-lance and the bushmaster. Other pitvipers have venom that could easily kill a person as well, however the fer-de-lance and the bushmaster bites are documented more in scientific studies. The venom of the fer-de-lance contains thrombin-like enzymes. It also contained more L-amino acid oxidase than most North American venoms. A common antivenom used against the fer-de-lance and other pitvipers is the polyvalent serum, which neutralizes the defibrillating, fibryonic activities of the different venoms in pitvipers. Certain studies have also shown that newborn pitvipers have the same toxicity, if not more than their parents do. Also for adolescent snakes, they may not know how to control their venom influx when they bite. Therefore immature and newborn snakes are just as dangerous as the parents are.
In conclusion, Costa Rica's snake population is wild and diverse. Not only is Costa Rica home to many venomous snakes, it is also home too many colubrid snakes. The different venomous snakes found in Costa Rica are not exactly easy to find. Most of the snakes in Costa Rica are nocturnal and usually just rest up during the day. If one is lucky enough to stumble across a snake, caution should first be taken, and then appropriate measures would follow. To ensure healthy populations of snakes for years to come certain measures need to be taken. Education is a major key to developing a sound ecological community for snakes. Locals need to be educated on what, where, and how to deal with snakes. Also public awareness of the ecological impact that snakes have on ecosystems needs to be stressed across the globe. By scientists continuing efforts to better understand snakes and all other organisms for conservation purposes, hopefully we can be ensured that generations to come can enjoy the same reptiles that we have today.
Checklist of the Amphibians and Reptiles of Rara Avis. http://www.rara-avis.com/herplist.htm
Costa Rica, Amphibians and Reptiles. http://www.photo.net/cr/moon/amhibians-and-reptiles
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Guyer C, Donnelly MA. "Length Mass Relationships Among Assembledge of Tropical Snakes in Costa Rica." Journal of Tropical Ecology. Vol. 6: 65-76, part 1. Feb. 1990
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Russell, F.E.. "Snakes and Snakebite in Centeral America." Toxicom. Vol. 35 no10. Pp.1469-1522. C 1997.
Miguel, Tanus Jorge. "Snakebite by the Bushmaster In Brazil." Toxicon. Vol. 35 no 4. Pp. 545-554. 1997.
Savage, Jay. "Evolution of coloration, urotomy and coral sanke mimicry in snake genus Scaphiodntophis." Biological Journal of Linnean Society. 52(2) 1996. 129-124.
Hardy, David L. "Bothrops asper (Viperidae) snakebite and field researchers In Middle America. Biotropica. Pp.198-207. 1994.
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