thumb|thumbtime=26|250px|[[Computed tomography–based model of a Lepidochelys kempii skull, with selected muscles highlighted]]

Kemp's ridley sea turtle (Lepidochelys kempii), also called commonly the Atlantic ridley sea turtle, Kemp's ridley turtle, and Kemp's ridley, is a species of turtle in the family Cheloniidae. L. kempii is the rarest species of sea turtle and is the world's most endangered species of sea turtle as well as the smallest. It is one of two living species in the genus Lepidochelys (the other one being L. olivacea, the olive ridley sea turtle). L. kempii primarily occupies habitat around the Gulf of Mexico, though its migrations into the Atlantic Ocean are being affected by rising temperatures. Kemp's ridley sea turtle is listed as endangered under the Endangered Species Act (ESA), and conservation efforts are attempting to rebuild population numbers. but the origin of the name "ridley" itself is unknown. Prior to the term being popularly used (for both species in the genus), L. kempii at least was known as the "bastard turtle".

At least one source also refers to Kemp's ridley as a "heartbreak turtle". In her book The Great Ridley Rescue, Pamela Philips claimed the name was coined by fishermen who witnessed the turtles dying after being "turned turtle" (on their backs). The fishermen said the turtles "died of a broken heart".

Description

Kemp's ridley is the smallest of all sea turtle species, with a carapace length of and weight of only at maturity. Typical of sea turtles, it has a dorsoventrally depressed body with specially adapted flipper-like front limbs and a beak. Kemp's ridley turtle adults reach a maximum of in carapace length and weighing a maximum of .

Kemp's ridley has a triangular-shaped head with a somewhat hooked beak with large crushing surfaces. The skull is similar to that of the olive ridley. Unlike other sea turtles, the surface on the squamosal bone where the jaw opening muscles originate faces to the side rather than to the back.

They are the only sea turtles that nest during the day. dark blue = adult female range;]]

The distribution of L. kempii is somewhat unusual compared to most reptiles, varying significantly among adults and juveniles, as well as males and females. Adults primarily live in the Gulf of Mexico, where they forage in the relatively shallow waters of the continental shelf (up to 409 m deep, but typically 50 m or less), with females ranging from the southern coast of the Florida Peninsula to the northern coast of the Yucatán Peninsula, while males have a tendency to remain closer to the nesting beaches in the Western Gulf waters of Texas (US), Tamaulipas, and Veracruz (Mexico). from the Atlantic are adults.

Feeding and life history

Feeding

Kemp's ridley turtle feeds on mollusks, crustaceans (such as floating crabs and shrimp), jellyfish, fish, algae or seaweed, and sea urchins. Juveniles primarily are pelagic surface-feeders, while adults are opportunistic bottom-feeders that feed primarily on crabs. Research has shown that dives made by these turtles, including those made to forage, may be longer at night. Comparing dietary habits of head-started turtles (turtles raised in captivity before release) and wild turtles found little difference in variance in feeding habits, but variability exists in feeding habits due to habitat differences and maturation of the turtles. Regional diet compositions aid in conservation efforts through enabling predicting food sources becoming affected by major events. Males will typically stay closer to breeding grounds.

Juvenile turtles tend to live in floating sargassum seaweed beds for their first years. Then, they range between northwest Atlantic waters and the Gulf of Mexico while growing into maturity.

They reach sexual maturity at the age of 10–12.

The nesting season for these turtles is April to August. They nest mostly (95%) on a 16-mile beach in the Mexican state of Tamaulipas and on Padre Island in the US state of Texas, and elsewhere on the Gulf Coast. They mate offshore. Gravid females land in groups on beaches in arribadas Females nest one to four times during a season, keeping 10 to 20 days between nestings. Incubation takes 6–8 weeks. Egg harvesting and poaching first depleted the numbers of Kemp's ridley sea turtles, And in the United States, Kemp's ridley turtle was first listed under the Endangered Species Conservation Act of 1970 on December 2, 1970, and subsequently under the Endangered Species Act of 1973. In 1977 an informal, binational multiagency, the Kemp's Ridley Working Group, first met to develop a recovery plan. This revision includes an updated threat assessment.

From 1947 to 1985, L. kempii nests experienced a sharp decline from an estimated 121,517 nests in 1947 to 702 nests in 1985 (decline of 99.4%), and have since been exponentially recovering until approximately 2011–2016, where another decline in nests occurred. Nesting as of 2016 is estimated to be 9.9% of the nest estimate of 1947. It is a grid of bars with an opening at the top or bottom, fitted into the neck of the shrimp trawl. It works by allowing small animals to slip through bars and get caught, while sea turtles strike the bars and are ejected through an escape hole on either the top or bottom of the device.). Wildlife officials released 10,594 Kemp's ridley hatchlings along the Texas coast in 2007. The turtles are popular in Mexico as raw material for boots and as food. A 2020 rescue mission to save 30 turtles from the freezing seas of Cape Cod was delayed by weather and technical issues, spurring a temporary rescue mission en route between Massachusetts and New Mexico. The Tennessee Aquarium offered overnight shelter and care, and the turtles were eventually released to the sea. These cold-stunning events may become more common with rising sea temperatures, as juveniles linger in near-shore waters in the American Northeast and are subjected to late-season storms.

As of June 13, 2025, 383 Kemp's ridley nests were documented on the Texas coast—breaking the previous record of 353 nests set in 2017 at Padre Island National Seashore.

alt=Thousands of Kemp's ridley females arriving at the beaches of Rancho Nuevo in 2017 to lay their eggs.|thumb|A Kemp's ridley arribada in Rancho Nuevo beach, Tamaulipas, Mexico, in 2017

Oil spills

Some Kemp's ridleys were airlifted from Mexico after the 1979 blowout of the Ixtoc 1 rig, which spilled millions of gallons of oil into the Gulf of Mexico.

Since April 30, 2010, 10 days after the accident on the Deepwater Horizon, 156 sea turtle deaths were recorded; most were Kemp's ridleys. Louisiana Department of Wildlife and Fisheries biologists and enforcement agents rescued Kemp's ridleys in Grand Isle. Most of the 456 oiled turtles that were rescued, cleaned, and released by the US Fish and Wildlife Service were Kemp's ridleys.

Of the endangered marine species frequenting Gulf waters, only Kemp's ridley relies on the region as its sole breeding ground.

As part of the effort to save the species from some of the effects of the Deepwater Horizon oil spill, scientists took nests and incubated them elsewhere; 67 eggs were collected from a nest along the Florida Panhandle on June 26, 2010, and brought to a temperature-controlled warehouse at NASA's Kennedy Space Center, where 56 hatched, and 22 were released on 11 July 2010.

The overall plan was to collect eggs from about 700 sea turtle nests, incubate them, and release the young on beaches across Alabama and Florida over a period of months.

Since the 2010 Deepwater horizon spill, scientists have identified the δ13C values present in turtle scutes to reflect the incorporation of oil. Exposure to oil and the subsequent incorporation of δ13C isotopes has been linked to lessened reproductive success of Kemp's ridley sea turtles.

References

Further reading

  • Garman S. (1800). On certain Species of Chelonioidæ. Bull. Mus. Comp. Zool., Harvard College 6 (6): 123–126. (Thalassochelys kempii, new species, pp. 123–124).
  • Database entry includes a brief justification of why this species is critically endangered and the criteria used
  • Profile from the OBIS-SEAMAP project of the Ocean Biogeographic Information System
  • Turtle Trax.org: Kemp's ridley sea turtle Profile
  • Coastal Research and Education Society of Long Island wiki Information on Kemp's ridley sea turtle
  • Information from the Florida Fish and Wildlife Conservation Commission
  • Texas Parks & Wildlife Dept. — Kemp's ridley sea turtle