Tuesday, November 22, 2016

Sao Paulo's Snake Island and It's Deadly Inhabitants

Just outside of Sao Paulo, Brazil, in the Atlantic Ocean, there is a legendary island that scares away fishermen and tourists. It is tiny and home to thousands of inhabitants that could kill you with a single bite. They live both on the ground and in the trees. This island is Ilha de Queimada Grande and its inhabitants are golden lancehead snakes (bothrops insularis).

Ilha de Queimada Grande is also known as "Snake Island" or the "Island of the Golden Snakes." Humans do not live on this island for fear of these creatures. In fact, the Brazil Navy enforces a no visitors rule with the exception of some scientists and those who accompany them. This is for the safety of visitors. It is also good for the golden lancehead. These snakes are indigenous to Ilha de Queimada Grande. One disaster could wipe them off the island and the Earth.

The inner part of Snake Island is thick forest. The outer edge is made up of steep, rocky inclines. There are no beaches, so access is limited. Very few other animals exist on this island, so the diet of most pit vipers is out of the question for the golden lancehead. This has made for an unusual adaptation. Golden lanceheads feed mainly on birds. Therefore, they not only spend a lot of time in trees, their venom has notoriously rapid results. Their prey has to be immobilized faster, as birds cannot be tracked on the ground if they fly away from their attacker. What this means for a human is that the necrosis and hemorrhaging caused by this venom occurs faster than that of this creature's equally deadly cousins.

Local fishermen tell stories about the island's last lighthouse keeper and the demise of his family. It is said that snakes snuck into the lighthouse and bit each of them as they slept. Not one survived. Another story is that of a fisherman who went ashore on Ilha de Queimada Grande, was bitten and made it back to his boat only to bleed to death in it before he could leave the island. The former story is rather strange because snakes do not display pack behavior. It seems highly unlikely that the snakes would come into the lighthouse and make it a point to bite everyone inside. The latter scenario is much more convincing. The anticoagulants in this snake's venom are quite dangerous.

Golden lanceheads are close cousins of the fur-de-lance. They can grow to be more than three-and-a-half feet long. Males are smaller than females. They are yellow in color and may have slightly darker, brownish markings. They thrive on Snake Island because they have no natural predators. It is said there is between one and five golden lanceheads on Ilha de Queimada Grande per 1.2 square yards. That is a lot of snakes for an area of that size. However, it is not a lot of snakes for a world population. That is why the IUCN has the golden lancehead on their critically endangered list.


Snake Island, retrieved 12/4/10, nationalgeographic.com/fieldtales/snakeisland