SEA TURTLES

Turtles belong to an ancient group of reptiles that date back to the Triassic Era 200 million years ago.  They are among the most distinctive and easily recognizable of all organisms.  Turtles are characterized by the presence of a shell that is composed of a 1.) carapace that covers the dorsal body, 2.) plastron that covers the ventral body, and 3.) bony bridge that connects the plastron to the carapace between the forelimbs and hindlimbs.  The carapace is formed from bones originating in the dermal layer that are fused with the ribs and vertebrate.  Scales (or scutes) derived from the epidermal layer cover the shell and provide additional protection.  The pectoral and pelvic girdles are located within the ribs, a unique feature not found in any other vertebrate.  Instead of teeth, turtles have a keratinous beak.  From the basic body plan of a turtle, adaptive radiation has resulted in the successful invasion of forests, grasslands, deserts, lakes, rivers, estuaries, and the ocean.  All turtles are oviparous ectotherms: they lay eggs and their body temperatures generally match the environmental temperature.

Five major clades of Testudines are currently recognized.  They are typically separated by details of the skull and shell structure, pattern of cranial arteries, and chromosomal morphology.  Sea turtles are found in two families: Dermochelyidae and Cheloniidae.  The leatherback sea turtle, with its shell that is reduced to small bony platlets, is the only extant species remaining in the Dermochelyidae family.  All other sea turtles (“hard shell”) are in the Cheloniidae family.

Sea turtles occur in all oceans and are wide-ranging throughout the tropical and temperature latitudes.  However, egg laying occurs only in tropical and warm-temperate habitats.  All species of sea turtles seem to share a similar life cycle where the adults move between foraging and breeding grounds.  Soon after breeding, females come ashore to deposit their eggs in the sandy substrate above the high tide line.  Females typically emerge from the ocean at night and will take up to two or three hours to complete the nesting process.  The process involves crawling to the upper beach (above high tide), digging a body pit, digging an egg chamber, depositing the eggs, covering the egg chamber, disguising the nest area, and then crawling back to the sea.   Individual females do not reproduce every year, although a female will deposit several large clutches of eggs within a single breeding season. 

Eggs incubate for about sixty days before the neonate turtles break from the egg and crawl to the sand’s surface.  Cued by cooling temperatures, hatchlings typically emerge from the nest soon after sunset.  As a group, the hatchlings from an individual nest swiftly crawl to the sea under the cover of darkness.  Hatchlings are generally attracted to light as they are typically guided to the sea by the brighter horizon over the ocean.  In today’s world, beach development has resulted in the hatchlings following the brighter horizon to hotels and parking lots where they are typically killed before ever reaching the ocean.

Sea turtles have long been exploited for the meat, eggs, shell, and skin.  This exploitation along with accidental catch in the fisheries has jeopardized the future of all sea turtle species.  It will take a lot of work, and a strong commitment, from the international community to remove these ancient reptiles off the path to extinction.  Each one of us can do our part to help the sea turtles and help the environment in which we live.  I hope you will continue reading this website to learn exactly what you can do to help sea turtle research and conservation programs around the globe.  Who knows, you may be the next person to tag a nesting sea turtle on a beach in West Africa.

There are historical records indicating five species of sea turtles use to nest in Ghana.  It has been many years since anyone has confirmed the nesting of a loggerhead or hawksbill turtle although fishermen do recognize seeing these two species when shown photographs of them.  We expect that the leatherback, olive ridley, and green turtle are the only species of sea turtles that are currently nesting in Ghana.