Introduction

The green sea turtle is a common resident of the Galapagos archipelago.  It is in fact an eastern specific subspecies, although many consider it to be a distinct species.  They acquired their "green" label as a result of their green body fat, which is due to their diet of algae.  They can be seen throughout the Galapagos, including Wolf Island, Darwin Island, in the waters close to Caleta Tortuga Negra on Santiago and off of southern Isabela.  Unfortunately the Pacific green sea turtle is an endangered species and newly laid eggs are vulnerable to predation.

Identification

Pacific green sea turtles have teardrop shaped blackish brown carapace, which tapers towards the rear with a slight keel.  The central plates are more or less equal in size, hexagonal in shape with straight edges.  They have a round head and slightly hooked beak.  The sexes are similar in appearance, although the males are significantly smaller than the females with a concave plastron. 

Behaviour

Male green turtles spend their entire lives in the sea, but females come to the shores of many of the islands usually only to lay their eggs.  Green turtle mating takes place in the sea, while the egg laying is done at night.  Egg laying generally occurs from December to June, with peak activity during February.  Green turtle eggs are very vulnerable and are often eaten by foreign invaders such as pigs.  Galapagos hawks, herons and mockingbirds destroy nests, while frigatebirds prey on young hatchlings.  Even after the hatchlings reach the sea, they are at risk of predation from sharks.  Overall, only a tiny proportion of hatchlings reach maturity.  Of these, some are ready to breed by the time they are 8 years old, while others are may not be ready for several decades.

Sea turtles are very powerful swimmers and have an incredible ability to determine which direction to travel, irrespective of ocean currents.  Interestingly, no matter how far sea turtles travel in their juvenile years, they will always make the long journey back to the beaches where they were originally hatched. Journeys of 1500 miles (2500 km) have been recorded.  Although somewhat of a mystery as to how, many believe that sea turtles steer by the sun and that they can sense the earth's magnetic field   

Pacific green turtles have salt glands behind each eye which help their bodies maintain a healthy water balance by shedding excess salt.  This process can only be described as crying - although there is no reason to be alarmed, as the turtles are simply keeping their body salt levels in check.

Diet

When the turtles first hatch, the yolk that remains in their stomach and sustains them for a short time, whilst they make the perilous journey into the ocean.  Upon reaching the ocean, the hatchlings feed on tiny plants and animals swept along by the currents including jellyfish, algae, shrimp and crustaceans.  The more mature green sea turtle's diet consists mainly of sea grass and mangrove leaves. 

Photographs kindly provided by Dan Holmes