THE 7 ENDANGERED SEA TURTLES SPECIES

Source: National Wildlife Federation

The tale of the sea turtles - the marine reptiles that inhabit all of the world's oceans except the Arctic - is a sad one. They are now threatened or endangered species, mainly due to human interventions, even though there are so many organizations trying to save them. Out of the seven turtle species that have been recognised living in the world's oceans, four of them can be found nesting on Malaysian shores.

Source: Redang Pelangi Resort Blog

The following article deals with each of the seven species (with pictures of Malaysian sea turtles added).

7 SPECIES OF SEA TURTLES
By Jennifer Kennedy, Marine Life About.com.

Sea turtles are classified in the Class Reptilia, Subclass Anapsida and Order Chelonii. There are seven recognized species of sea turtles, six of which (the hawksbill, green, flatback, loggerhead, Kemp's ridley and olive ridley turtles) are in the Family Cheloniidae, with only one (the leatherback) in the Family Dermochelyidae. All seven species of sea turtles are listed under the Endangered Species Act.

1. Leatherback (Dermochelys coriacea)

Credit & Source: Daniel Evans/Caribbean Conservation Corporation.

The leatherback is the largest sea turtle and can reach lengths over 6 feet and weights over 2,000 pounds. These animals are deep divers, and have the ability to dive to over 3,000 feet. Leatherback turtles nest on tropical beaches, but can migrate as far north as Canada during the rest of the year. This turtle’s shell consists of a single piece with 5 ridges, and is distinctive from other turtles who have plated shells.

Post-nesting leatherback turtle (penyu belimbing) photographed in Rantau Abang, Terengganu.  Photo credit: E.H. Chan. Source: Turtle Conservation Centre.

2. Green Turtle (Chelonia mydas)

Source: Caribbean Conservation Corporation.

The green turtle is large, with a carapace up to 3 feet long. Green turtles weigh up to 350 pounds and their carapace can be many colours, including shades of black, grey, green, brown or yellow. Adult green turtles are the only herbivorous sea turtles. When young, they are carnivorous, but as adults they eat seaweeds and seagrass.  They are found in tropical and sub-tropical waters around the world.

A post-nesting green turtle (penyu agar/penyu pulau) photographed in the Chagar Hutang Turtle Sanctuary, Redang Island, Terengganu. Photo credit: Jeremy Liew. Source: Turtle Conservation Centre.

3. Loggerhead (Caretta caretta)

Credit & Source: Juan Cuetos/Oceana

Loggerheads are a reddish-brown turtle that have a very large head. They are the most common turtle that nests in Florida. Loggerhead turtles can be 3.5 feet long and weigh up to 400 pounds. They feed on crabs, mollusks and jellyfish.

4. Hawksbill (Eretmochelys imbricate)

Courtesy Silke Baron, Flickr.

The hawksbill turtle grows to lengths of 3.5 feet long and weights of up to 180 pounds. Hawksbill turtles were named for the shape of their beak, which looks similar to the beak of a raptor. These turtles have a beautiful tortoiseshell pattern on their carapace, and were hunted nearly to extinction for their shells. Hawksbill turtles live in tropical waters and feed on sponges.

Post-nesting hawksbill turtle (penyu karah/penyu sisik) photographed in Chagar Hutang Turtle Sanctuary, Redang Island, Terengganu. Photo credit: Alarick. Source: Turtle Conservation Centre.

5. Kemp's Ridley (Lepidochelys kempii)

Credit & Source: David Bowman, U.S. Fish & Wildlife Service.

At lengths up to 30 inches and weights of 80-100 pounds, the Kemp’s ridley is the smallest sea turtle. They are coastal turtles and found in temperate to sub-tropical waters in the western Atlantic and Gulf of Mexico. They prefer to eat benthic organisms such as crabs.

6. Olive Ridley (Lepidochelys olivacea)

Credit & Source: Sebastian Troëng/Sea Turtle Conservancy

Olive ridley turtles are named for - you guessed it - their olive-coloured shell. Like the Kemp’s Ridley, they are small, and weigh less than 100 pounds. They are found in tropical regions around the world. They eat mostly invertebrates such as crabs, shrimp, rock lobsters, jellyfish, and tunicates, although some eat primarily algae.  When nesting, females come to shore in colonies of up to a thousand turtles and have mass nesting aggregations (arribadas) on the coasts of Central America and East India.

Olive ridley turtle (penyu lipas). Fragmentary and occasionally reported in the Sarawak Turtle Islands, Penang, Terengganu and Kelantan. Source: Turtle Conservation Centre.

7. Flatback (Natator depressus)

Flatback turtles are named for their flattened carapace, which is olive-gray in colour. The flatback turtle is only found in Australia and lives in coastal waters. They eat squid, sea cucumbers, soft corals and mollusks.

A flatback turtle hatchling crawls to sea. Source: Wikipedia.

Suggested Reading:
1. Learn About Sea Turtles
2. Sea Turtle Photos and Facts
3. Sea Turtles and Oil Spills

Source:
1. Marine Life About.com
2. Turtle Conservation Centre

[Edited. Some images added.]