Sea Turtles

sea turtles creatures which when adult are relatively immune to predators (apart from certain large sharks, whales, and human beings) but whose pattern of reproduction renders them vulnerable to extinction, belong to the order Chelonia (or Testudines) and have a very long history, stretching back to the time of the dinosaurs, 90 million years or so ago.

There are seven surviving species of sea turtle, of which six have a global distribution in tropical or subtropical waters. Many have well-defined feeding areas, such as shallow waters with a plentiful supply of marine grasses, and all have a limited number of ‘rookeries’ for reproduction. If only these creatures had been able to develop a viviparous capability, so that they could give birth to their babies at sea, they would have an assured future. Unfortunately, however, they stayed with the technique of laying eggs on land, specifically on beaches with certain characteristics, and this may spell their eventual doom. Where the beaches used by the various species have been identified, efforts may be made to prevent at least human predators from digging up the eggs; but in the case of mainland beaches it seems all but impossible to protect the eggs from raccoons and foxes. (It should not be thought that the turtles are careless about depositing their eggs. On the contrary, they go to great lengths to excavate deep holes in the sand— Bustard (1972) records finding dead turtles, stricken by a heart attack brought on by the intense physical effort, poised over the holes they were making—and to cover their traces afterwards. But several predators can detect the eggs by smell, even though they are buried deep.)