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Kemp's Ridley Sea Turtle, Lepidochelys kempii, Family Cheloniidae, pictures, stock photos, images

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Other common names: Ridley, Atlantic Ridley, Bastard Ridley, Bastard Turtle, Tortuga Lora (Spanish) (Witherington, 2006)

The Kemp’s Ridley and the Olive Ridley are close relatives and occupy the same genus. Recent genetic information suggests that they diverged into separate species about 3 to 4 million years ago.

The name Kemp comes from Richard M. Kemp, the fisherman who first submitted a specimen of this species to Harvard naturalist/zoologist Samuel Garman for study. Garman described the species in 1880, but it was not officially recognized as a distinct species until the 1940s. Even then, there was some dispute about its status, with some herpetologists suggesting it was a hybrid of other species.

The Kemp’s Ridley Sea Turtle, Lepidochelys kempii, is among the smallest of sea turtles, and about the same size as its relative, the Olive Ridley Sea Turtle, Lepidochelys olivacea. It is found in the Gulf of Mexico and the north Atlantic, while the Olive Ridley is generally found elsewhere. It is the only species of sea turtle that mainly nests during daylight hours, and it has just one major nesting site, a small beach near Rancho Nuevo in Mexico. It is a fast-moving, agile sea turtle that will fight vigorously when captured.

Kemp’s Ridley females weigh 35-45 kg (75 to 100 lbs) and have a carapace length of from 60 to 70 cm (25 to 28 in) (Witherington, 2006). They have a flatter carapace than the Olive Ridley, and their shell is sometimes as wide as it is long, making it almost circular. Their carapace is smooth and generally not home to barnacles.

Kemp’s Ridleys are olive-green, but lighter in color and more grayish brown than Olive Ridleys. Their plastron is yellowish to cream colored. Kemp's Ridleys have one claw on each front flipper and two on each rear flipper. They have two pairs of prefrontal scales, and five pairs of lateral scutes. The number of lateral scutes generally does not vary, as it does with Olive Ridleys. Males have longer tails than females.

Like Olive Ridleys, Kemp’s Ridleys have conspicuous openings leading from the Rathke’s glands on the lower portion of their shells. The purpose of the Rathke’s glands is unclear, but they may secrete pheromones or a substance that repels predators.

Kemp’s Ridley Sea Turtles have the second smallest range of any sea turtle (the Australian flatback having the most limited range). They are found almost exclusively in the Gulf of Mexico, where Olive Ridleys are generally not found. Some juveniles have been found on the Atlantic coast of the U.S., and a few rare specimens have been found in the open Atlantic and along the coast of Europe and North Africa. While a few individuals have been found nesting in Texas and Florida, the majority of Kemp’s Ridleys nest at one beach near Rancho Nuevo, Mexico.

Kemp’s Ridley Sea Turtles, like olive ridelys, feed on sea jellies, pelagic snails, and crabs. One of their most preferred foods is the Blue Crab, Callinectes sapidus, which is found in quiet bay waters. They also eat clams, mussels, jellyfish, and the fish bycatch discarded from shrimp trawlers.

Hawksbill Sea Turtle underwater image
Picture of Kemp’s ridley sea turtle, Lepidochelys kempii, endangered species, returns to sea after nesting, Rancho Nuevo, Mexico, Gulf of Mexico. Image #: 003794

Kingdom: Animalia

Phylum: Chordata

Subphylum: Vertebrata

Class: Reptilia

Order: Testudines

Suborder: Cryptodera

Superfamily: Chelonioidea

Family: Cheloniidae

Genus Species: Lepidochelys kempii

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The story of how the Kemp’s Ridley nesting site near Rancho Nuevo, Mexico, came to be known is an interesting one. For years, no herpetologists knew where Kemp’s Ridleys nested, as no nesting behavior had ever been witnessed. Then, in 1960, Dr. Henry Hildebrand, of the University of Corpus Christi, Texas, discovered an obscure film that documented a Kemp’s Ridley arribada. An arribada is a nesting event common among Olive Ridleys whereby many thousands of sea turtles congregate at one nesting site and lay their eggs in close proximity to each other. The film, taken in 1947 by Mexican engineer, Andres Herrera, was of his chance encounter with a Kemp’s Ridley arribada at Rancho Nuevo. It documented an estimated 42,000 turtles arriving to nest. By 1968, however, only 5,000 turtles were nesting at the site, and by the 1980s, only 200 could be found nesting there. The rapid decline was due to locals harvesting the eggs for sale, and later to shrimp trawlers capturing the turtles as bycatch.

Thanks to recent efforts to protect the critically endangered Kemp’s Ridley, the number of nesting females has increased somewhat. A Rancho Nuevo arribada now numbers over a thousand individuals. Females nest every year and one to three times each season, laying about 100 eggs in a nest. Two weeks to a month pass between each nesting. Hatchlings leave their nests in 45 to 60 days and weigh about 17 g (1/2 oz) each. They reach adulthood in 10 to 15 years.

Two features of the Kemp’s Ridley nesting behavior distinguish it from that of the Olive Ridley. First, Kemp’s Ridley arribadas occur in daylight, while Olive Ridley arribadas occur mainly at night. Second, Kemp’s Ridleys rock from side to side after nesting, in what appears to be a kind of dance. The purpose of this movement appears to be to compact the sand over their nesting site.

The IUCN lists the Kemp’s Ridley as Critically Endangered. Although the Mexican government protects the Rancho Nuevo nesting site, Kemp’s Ridleys are still at risk of extinction due to their limited nesting range. The Gulf of Mexico is a key oil drilling area, and just one major oil spill could be devastating to the Kemp’s Ridley population. Efforts have been made to establish other nesting sites, but with limited success to date. There are an estimated 5,000 adult females in existence today.

• Kemp's Ridley Sea Turtle information assembled from published and on-line sources by Kevin Miller on Jan. 20, 2007 for SeaPics.com.

Sources:

Perrine, D. Sea Turtles of the World, Voyageur Press, 2003

Ripple, J. Sea Turtles, Voyageur Press, 1996

Witherington, B. Sea Turtles, Voyageur Press, 2006

http://marinebio.org/species.asp?id=317

http://www.orf.org/turtles_kempsridley.htm

http://en.wikipedia.org/wiki/Samuel_Garman