The Kemp’s ridley is a small sea turtle, weighing less than 45 kg as adults, with a carapace length of 65 cm. The shell is almost as wide as it is long. Hatchlings are 42–48 mm long and weigh 15–20 g. The carapaces of adult Kemp’s ridley turtles are light grey or olive, and the plastrons are creamy white or yellow. Males have a longer tail than females with a more distal vent; recurved claws; and a softened plastron during the breeding season. There are two pairs of prefrontal scales on the head, five vertebral scutes, five pairs of costal scutes, and usually twelve marginal scutes. The bridges between the carapace and plastron have four scutes, each perforated by a pore. The head is triangular with a slightly hooked beak.
Can be Confused With
Kemp’s ridley turtles might be confused with their cogener, the olive ridley. The Kemp’s ridley turtle consistently has five costal scutes, whereas the olive ridley’s costal scutes are often divided so that they may have as many as nine. The Kemp’s ridley might also be confused with loggerhead sea turtles, but they are smaller and their carapace is lighter in color.
The Kemp’s ridley has a subtropical range and is found primarily in the Gulf of Mexico, but occurs along the Atlantic coast of the United States and Canada as well; in rare circumstances they are found in the eastern North Atlantic after crossing the Gulf Stream.
Ecology and Behavior
Kemp’s ridley sea turtles have a coastal habitat and nest in large aggregations between April and June in Rancho Nuevo, on the northeastern coast of Mexico in southern Tamaulipas. Mating has been observed just offshore of the nesting beaches. Females typically nest every two years, laying an average of 2.5 clutches each containing approximately 100 eggs. Age at maturity is estimated to be 7-15 years. Distribution of hatchlings is largely dependent upon currents in the western Gulf of Mexico. They have been found living in floating mats of vegetation in the Gulf of Mexico and Atlantic Ocean. When turtles reach 20-25 cm, they begin to use coastal benthic habitats in the Gulf of Mexico and along the United States Atlantic coast, often found near the red mangrove shoreline of the Florida Keys.
Feeding and Prey
Kemp’s ridleys have a focused diet; for adults, diets consist of: crustaceans>mollusks>algae while diets are dominated by algae for juveniles. Little is known regarding the diet of hatchlings, but they likely feed on sargassum and associated fauna.
Adult Kemp’s ridleys are benthic feeders. They may migrate long distances between coastal feeding grounds. Although plants comprise a significant portion of items found in Kemp’s ridley’s digestive tracts, this may be due to incidental ingestion in the course of preying on crabs, mollusks, and other animals.
Kemp’s ridleys have a seizing feeding mode and prey species include:
For juveniles: Sargassum sp., Recluzia rollandiana, Cavolina longirostris, Litiopa melanostoma
Threats and Status
Threats for Kemp’s ridleys include the harvest of eggs/adults, fisheries bycatch, loss of habitat, oil and plastic pollution, incidental take from dredging, and entanglement in debris/fishing gear.
The Kemp’s ridley sea turtle is listed as critically endangered by the IUCN and is on the endangered species list in the United States. A dramatic decline in the population makes this turtle the most endangered of all the sea turtles. In 1947, 42,000 females were filmed nesting in one day in Rancho Nuevo, Mexico. Because females nest in large groups (arribadas), the adults and eggs are particularly vulnerable to harvest. The total number of nests laid in 1985 was reduced to 740, highlighting the need of conservation of the Kemp’s ridley. The Mexican government now protects many of the nests at Rancho Nuevo. A slow recovery of the species may be in the early stages, demonstrated by the fact that over 6,000 nests were found on the Mexican coast in the year 2000.
Ernst, C.H. and R.W. Barbour. 1989. Turtles of the World. Smithsonian Institution Press, Washington, DC.
Lutz, P.L and J.A. Musick (Eds). 1997. The Biology of Sea Turtles. CRC Press LLC, New York, NY.
Turtle Expert Working Group. 2000. Assessment Update for the Kemp’s Ridley and Loggerhead Sea Turtle Populations in the western North Atlantic. U.S. Department of Commerce NOAA Technical Memorandum NMFS-SEFSC-444, 115 pp.