Sea Turtles2018-11-23T16:18:08+00:00

Green Turtle

Description

Found in Kenyan waters

Scientific name: Chelonia mydas
IUCN red list status: Endangered
Size: Can grow up to 1.5m carapace length
Weight: Up to 250kg
Feeding: Herbivore
Lifespan in wild: approx. 50 years

Greens are found to inhabit tropical and subtropical coastal waters around the world.

The sub species of the green turtle is found only in the Pacific Ocean, usually named the pacific green or the black turtle. It has an light or dark brown carapace with a yellowish white plastron. Unlike the green, the black turtle when mature is still an omnivore; this is why they have a darker colour skin and carapace. The green turtle was not named because of the colour skin it has or because of its carapace, but for the green colour of its fat. Greens are herbivores when mature, feeding on sea grass and algae. As juveniles green turtles are omnivores and will feed on small invertebrates like crabs, jelly fish and sponges.

This is the only species of turtle that has been seen to bask on quiet islands in Hawaii and the Galapagos islands. It is presumed that the turtles are taking in the sun to warm their bodies or possibly evading predators like Tiger sharks.

Males are larger than females and have a longer tail, this helps to distinguish sex. Males also have larger claws which are used during mating. Mating occurs every two to four years and the turtles will usually move in-shore for this, green turtles are spotted regularly in Watamu Marine Park and Marine Reserve mating.

A green female will lay, on average, 110 eggs per clutch, she will emerge between 3 – 7 times to lay eggs in a single nesting season, usually with a 12-14 day nesting interval.

Sea turtles have many predators but for green turtles humans have been their biggest threat. This species is regularly slaughtered for its meat, eggs, oil and carapace. The meat was highly sought after in many countries in the form of turtle soup! Nowadays greens are slaughtered and the meat is distributed on the black market where it can fetch a very high price.

Hawksbill Turtle

Description

Found in Kenyan waters

Scientific name: Eretmochelys imbricata
IUCN red list status: Critically endangered
Size: up to 1.2m in carapace length
Weight: up to 70kg
Feeding: Omnivore
Lifespan in wild: up to 50 years

Hawksbill turtles are found to inhabit the tropical waters of the Atlantic, Pacific, and Indian Oceans. They are mostly found in shallower waters, preferring reef areas where sponges are abundant and sandy nesting sites are nearby.

These turtles have a striking coloured carapace of dark brown and amber, with serrated marginal scutes and lateral scutes that overlap when young and it has a whitish yellow plastron. Like its name suggests, this turtle has a bird like keratin beak which is adapted for scraping sponge from the coral reefs. Hawksbills are omnivorous and will also eat molluscs, algae, sea grass, crustaceans, sea urchins, fish, and jellyfish. Hawksbills are one of the only creatures that can consume the toxic species of sponge, they are not poisoned by this but their flesh retains the toxins and can be passed onto predators who feed on this species. A number of incidences have occurred in Kenya where a whole family has died due to consuming toxic hawksbill meat.

These turtles are integral to a healthy coral reef ecosystem. Using their hawk like beak they clean the coral by scraping and feeding on the sponges that otherwise smother the coral, this prevents photosynthesis and the coral will die.

The female comes ashore and can lay around 130 eggs in each nest, she will usually emerge 4 times to nest in 1 season.

This species was nearly wiped out due to the huge international trade in sea turtle shell, which came from the hawksbill, to make jewellery, frames and ornaments from the 1950’s up to the early 1990’s. Much of these shells/parts were exported to Japan. Since the hawksbill Turtle was listed in Appendix I of Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), international trade in the species and its products has been prohibited unless the purpose of trade is non-commercial.

Leatherback Turtle

Description

Scientific name: Dermochelys coriacea
IUCN red list status: Critically endangered
Size: up to 2.5m carapace length
Weight: up to 900kg
Feeding: Carnivorous
Lifespan in wild: less than 50 years

Leatherback sea turtles do not usually nest in Kenya, however this female emerged on our nesting beach!

The leatherback turtle has the largest distribution of all sea turtles and are found as far North as Canada and as far south as South America. They are largest turtles on Earth reaching up to 2.5m in carapace length, nowadays they tend to average at 1.5m carapace length.

All sea turtles have a hard keratin carapace to protect themselves, except the leatherback turtle. The leatherback has 7 boney keels or ridges running down its cartilaginous back covered with a thick black leathery skin with white spots. These keels help to make the leatherback hydrodynamic in the water, making it the fastest sea turtle in the ocean.

Leatherbacks can dive to as deep as whales, as far as 1200m, much deeper than any other sea turtle. They can hold their breath for over an hour. Another adaptation this species exhibits that other species of turtle do not is that they are able to maintain a warm body temperature in cold water. They do this using their large body size, changes in swimming activity and blood flow, and a thick layer of fat. They also migrate further than any species of sea turtle to travel between their breeding and feeding grounds, averaging 6,000km each way.

They are renowned to feed primarily on jellyfish, but they also consume other soft-bodied animals such as tunicates. Scientists suggest that to sustain an animal of its size, they would have to consume up to 1000 jellyfish per day. With the rapid decline of leatherbacks worldwide, a high influx of jellyfish has been documented.

Leatherbacks lay approximately 80 eggs in each nest, including a layer of infertile eggs on the top as a way of protecting the nest from predators; they will have their fill of the infertile eggs and hopefully leave the fertile eggs still in the nest. In one season a single female may come up to nest 10 times!

Some populations of leatherback seem to be stable but others, e.g. the Pacific population is currently declining at an unsustainable rate, this is due to egg harvest, fishery by-catch, coastal development, amongst others. Some of these Pacific populations have disappeared entirely.

Loggerhead Turtle

Description

Found in Kenyan Waters

Scientific name: Caretta caretta
IUCN red list status: Endangered
Size: up to 1m
Weight: up to 120kg
Feeding: Primarily Carnivorous
Lifespan in wild: up to 50 years

The loggerhead occurs throughout temperate and tropical regions of the Atlantic, Pacific, and Indian Oceans. Data indicates that this species prefers coastal habitats, however, they will travel hundreds of miles out to sea on their migrations.

Loggerheads are the largest of all hard-shelled turtles; they have massive heads (named because of its enormous head), strong jaws, with a reddish-brown carapace and brown or yellowish platron. It has been found to feed on jellyfish, conchs, crabs, fish, as well as eat seaweed and sargassum on occasion. The loggerhead female comes ashore every 2 to 4 years to nest. The female will lay on average around 112 eggs in a single nest and can return up to 4 times, with a 12 – 17 day nesting interval, to lay more clutches of eggs.

All sea turtle species face threats on both their nesting beaches and in the marine environment. The main cause of decline to loggerhead populations worldwide is incidental capture in fishing gear, primarily in long-lines and gillnets, trawls, dredging as well as traps and pots also play a role.

Olive Ridley

Description

Found in Kenyan Waters

Scientific name: Lepidochelys olivacea
IUCN red list status: Endangered
Size: up to 70cm
Weight: up to 45kg
Feeding: Omnivore
Lifespan in wild: up to 50 years

This species is mainly found in warmer waters, including the southern Atlantic, Pacific and Indian Oceans. They are the most abundant species of sea turtle as well as sharing the spot for the smallest species.

The Olive Ridley was named after the olive green colour of it’s skin and carapace, with a greenish, yellow plastron. It has a unique hump on its carapace that makes it easily distinguishable from other species. The Olive Ridley is a not too fussy omnivore, feeding on small crustaceans, jellyfish and shrimp as well as sea grass, algae and seaweeds.

This species is a solitary nester like all other species of sea turtle, however Olive Ridleys are also known to nest in a method known as ‘arribada’. This means that on a small handful of specific beaches worldwide they come ashore en masse to lay their nests. In one ‘arribada’ up to 400,000 females may come ashore to nest at the same time.

Olive Ridleys are the quickest of the sea turtle species on land and the fastest nester. They take between 45 minutes and 1 hour to nest. A female will lay on average 100 eggs, all around the size of a ping pong ball. The female will come ashore to nest up to 3 times in each season every 2 to 3 years. While the female is covering her nest you will hear a ‘thump thump thump’, this is known as the ‘Ridley dance’. This noise is made by packing sand into their nest using their plastron.

Even though this is the most abundant species of sea turtle, their numbers are rapidly declining worldwide due to by catch, poaching (for their skin and eggs), pollution and over development on nesting beaches.