August 2017 – Part II
The following anatomy terms are mentioned in the blog.
Carapace – The hard upper shell (dorsal section) of a tortoise, turtle, crustacean, or arachnid.
Scutes – Scales forming carapace.
Plastron – The underside, bony plate, forming the ventral part of the turtle’s shell; i.e. its breastplate.
Clutch – A clutch is a nest of eggs which were laid at the same time.
In Costa Rica, the families of Sea Turtles nesting here are the Olive Ridley, Kemp’s Ridley, Pacific Green, Hawksbill, Loggerhead and Leatherbacks. Here is the sea turtle guide; the species and their peculiarities, including a description to assist in their identification; understanding their habits; and, their population status.
Olive Ridley (Lepidochelys olivacea)
The Olive Ridley earned its name from the color of its shell. Measuring 2’ to 2.5’ (62- 70 cm) in length, the carapace is made-up of 6 lateral, smooth scutes and is almost completely circular in shape. The adult body is deeper thank the Kemp’s Ridley sea turtle, and weighs between 70lbs. to 100lbs. (45.5 kg).
Habitat: Olive Ridleys are mostly found in the west-north Atlantic; mainly in Costa Rica, Suriname and other adjacent areas. They can also be found in the Pacific and Indian Oceans as well.
Diet: Olive Ridleys are omnivores enjoying a diet of crustaceans- crabs, shrimp, mollusks, fish and occasionally seaweed. They search the surface for food as well as diving to feed on the ocean bottom, up to 500 feet (150 m) below the surface.
Status: Most regions reported declines in the number of nesting’s; estimated declines of over 80% since 1966. Pacific nesting places are considered, by environmentalist, to be relatively stable and enjoying marginal increases annually. Their spectacular beach invasion for nesting is called an arribada; which in Spanish means ‘the arrival’.
Kemp’s Ridley (Lepidochelys kempii)
These are the most ‘critically endangered’ of all the sea turtles. They too nest in mass arrivals or arribadas, similar to the Olive Ridleys. The most recently identified member of the Ridley; they owe their individuality to Richard Kemp who discovered, researched and documented the specie. Kemp’s Ridleys nest more often than any other turtle; on average every 1- 3 years they lay 2 or 3 times each season; laying approximately 110 eggs in each clutch.
Their carapace has 5 large, lateral scutes; fully grown their overall measurement is 2’ (60 cm). Adults are dark-grey-green on the top-shell and yellowish or white on the plastron. The young hatchlings are black. An adult Kemp Ridley weighs 80 – 110 lbs (32 -50 kg).
Habitat: They enjoy living in shallow coastal waters, preferring sandy or muddy shallow bottoms.
Diet: Kemp’s Ridleys feed on crabs, shrimp, clams, mussels, fish, sea urchins, jellyfish and squid.
Status: This specie is classified as ‘CRITICALLY ENDANGERED’.
Hawksbill (Eretmochelys imbricata)
Description: These sea turtles are equipped with a narrow beak affixed to an equally narrow head; thus, its name.
Size: Adults grow to 2.5 feet – 3 feet (70 cm – 90 cm)
Habitat: Best place to view is in Cahuita National Park, Limon; northwest Caribbean Coast. They prefer life on coastal reef, estuaries, rocky structures and lagoons.
Diet: It enjoys a diet of sponges, anemones, shrimp and squid. The bill of the Hawksbill allows it to easily extract food from pockets in the reef. It assists Parrotfish and others to clean the reef by taking care of the sea sponges.
Range: The most tropical of all sea turtles, predominantly found in the Caribbean, the Atlantic, Pacific, and Indian Oceans.
Nesting: The Hawksbill is a solitary nester, making population estimates hard to estimate. Laying every 2 years to 4 years, and 3 to 6 times per season, the average Hawksbill’s clutch is 160 eggs. Nesting can be viewed year-round but records show it is heaviest between March and October.
Status: CRITICALLY ENDANGERED– In 1983 stable populations were discovered in Yemen, N.E. Australia, Oman and the Red Sea. They are scarcely seen in the USA, but are popular in Costa Rica and throughout the Caribbean.
Threats: It is important to specify the biggest threat to this specie; its shell is favored for souvenir items. For centuries the shell of the Hawksbill has been used to fashion ornaments, jewelry, and decorative articles. Although Hawksbills are protected in most countries, little has been done to stop local craftsmen for hunting them for fashion purposes. Like all sea-turtles, their meat and eggs are highly sought commercially.
Pacific Green (Chelonia agassizii)
The Pacific Green family is large; it is also known as the Eastern Pacific Green Turtle, the Galapagos Green Sea Turtle, and also the Black sea turtle. The Pacific Green is a cousin of the Atlantic Green family (Chelonia mydas) and lives in different oceans. All are subspecies of the Cheloniidae family and are all endangered.
Description: The Green Sea Turtle gets its name from a greenish colored fatty layer under the carapace. The fat gets its hue from the chlorophyll drawn from its diet of aquatic vegetation. A serrated jaw helps adults chew the veggies. Like the Hawksbill they keep the reefs tidy by trimming the vegetation growing there.
Size: 30 inches to 60 inches (75 cm to 152 cm)
Weight: Up to 700 lbs (315 kgs)
Habitat: Costa Rica and the Pacific Caribbean Sea, the Galapagos Islands, favoring mangrove swamps.
Range: Found in the Hawaiian Islands; from the California coastline through Central America to Chile and the Galapagos Islands; Canada down the US Eastern seaboard to Suriname and French Guiana in South America.
Diet: Herbivorous, eating mostly mangroves, algae, seagrasses, and kelp.
Nesting: Nest year-round, mostly between December and March.
The Loggerhead (Carretta caretta)
The Loggerhead (Carretta caretta) is found in Honduras, Mexico, Colombia, Israel, Turkey, Bahamas, Cuba, Greece, Japan, Costa Rica and Panama. The species is declining but is not on the critically endangered list.
Description: Very strong jaws are mounted on its large head. The carapace is heart-shaped; five hexagonal central scutes are surrounded by 50 non-overlapping scutes on either side. The carapace is reddish-brown and its underside, plastron, is a yellowish-brown. Young hatchings are dark brown with pale brown flippers.
Size: Adult Loggerhead carapaces measure 2.5’ to 3.5’ (80- 100 cm), and weigh 150lbs. to 375lbs (70- 170 kg).
Diet: A Carnivore feeding on crabs, mussels, shellfish and invertebrates, living on the seabed. Their powerful jaws are perfect for crushing their meals.
Habitat: They prefer shallow waters, bays and estuaries along the continental shelves of the Atlantic, Pacific and Indian Oceans.
Nesting: Loggerheads nest every 2 to 4 years; then they lay 3 to 6, approximately 12 to 14 days apart. Each clutch will contain 90 to 125 eggs. Incubation period is 60 days.
Status: Currently facing a high risk of extinction. Coastal development plays a big role in the diminished numbers of Loggerheads. Development and physical changes to the shoreline, combined with the confusion Sea Turtles experience from lights, cause many hatchlings to never make into the water. Additionally, there is the ever-present list of natural predators- plastics, man, fishing trawlers and other catching gear.
Leatherback (Dermochelys coriacea)
As the name implies, the Leatherback does not have a hard epidermal scutes over its back; instead it has a leathery covering to protect it. The last living member of the taxonomic Dermochelys species; it grows the largest; travels farthest; dives deepest.
The population declines at a rate of 22% annually.
Size: 4 ½’ to 5’ 6” (140- 160 cm); 1,800 lbs (900 kgs). This is the only sea turtle that has no claws.
Habitat: Found on- the Pacific Coast of Mexico, Costa Rica, Malaysia, India, Sri Lanka, Thailand, Trinidad & Tobago, and Papua New Guinea; everywhere except Antarctica.
In Costa Rica they are frequently seen on the Osa Peninsula, Boca de Matina, Playa Ostional, Playa Gandoca, Playa Naranjo, and Playa Grande.
Diet: Gelatinous zooplankton, jellyfish, squids, etc.
Nesting: Lays 4-7 clutches per nesting season; and 60 to 70 eggs per clutch.
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