Marine Reptiles: Sea Living Snakes, Iguanas, Crocodiles, Turtles
There are 62 species of snake, one lizard, one crocodile, and seven turtles living in the world’s oceans today. Many more reptiles lived in the sea in the past.
These reptiles spend most, or all of their time at sea. Some are so well adapted to life in the water that they have lost the ability to move effectively on land. They are all air breathing, so they need to surface to breathe. They feed mainly on fish and all are venomous, some deadly.
The Marine Iguana
Amblyrhynchus cristatus is found only on the Galapagos Islands, and it is the only living marine lizard. It spends much of its time ashore, but enters the water and dives down to browse on seaweeds.
The Saltwater or Estuarine Crocodile
Crocodylus poros is the largest of all living reptiles. It can be over 20 feet long, and weigh as much as 800kg. Enormous adults will eat anything they can grab, including humans and fully grown water buffalo! They are found from Northern Australia to India, and spend part of their time in estuaries and part far out at sea. There are only one or two human deaths per year in Australia, but hundreds are thought to be killed by these crocodiles every year in the rest of their range. The only natural enemies of an adult Saltwater Crocodile are Tiger and Great White Sharks – and other adult crocodiles!
There are seven species of Sea Turtle alive today, and they are found in all the world’s oceans except the Arctic Ocean. The Green Turtle (Chelonia mydas) can be found in all tropical and sub-tropical waters, both in the Atlantic and the Pacific. All species need to come ashore to lay their eggs, and this is where they are most vulnerable. All are threatened to some extent, but the Leatherback, Kemp’s Ridley, and Hawksbill Turtles are listed as critically endangered
Extinct Marine Reptiles
There were once many superbly adapted marine reptiles, but most died out around 65 million years ago with the dinosaurs, and their niches have been taken over by the marine mammals.
There are tantalising myths and legends from around the world that hint at the possible survival of some ancient marine reptiles in large deep freshwater lakes. The ‘Loch Ness Monster’ in Scotland is one example, the ‘Ogopogo’ in Lake Okanagan, British Columbia another. While most zoologists remain highly sceptical about their possible survival some people have suggested that they might be descendents of the plesiosaurs. (Look at the reconstruction of ‘Ogopogo’!)