By Zachary Klug
Geographic Range
Kemp’s Ridleys (Lepidochelys kempii) can be found from Nova Scotia and Newfoundland to Bermuda. Nesting Ridleys are found mainly in the Gulf of Mexico. In migration, they follow two major routes: one heads north to the Mississippi coastline and the second extends southward to the shores of the Yucatan Peninsula at the Campeche Bank. (Ernst and Barbour, 1972; U.S. National Park Service, 2003; Wilkinson, 2003)
Biogeographic Regions:
nearctic 
(native ); neotropical (native ); atlantic ocean (native ).
Habitat
Lepidochelys kempii mainly stays near shallow coastal regions characterized by bays and lagoons. These turtles prefer waters that have sandy or muddy bottoms, but also may take to the open seas. At sea, this species has the ability to dive to great depths.
This species is rarely seen on shore, but it is not uncommon to see L. kempii floating in the water just offshore. Females come on shore to nest. (Ernst and Barbour, 1972)
These animals are found in the following types of habitat:
tropical ; saltwater or marine .
Aquatic Biomes:
coastal .
Physical Description
(66 to 110 lbs)
(21.65 to 29.53 in)
Lepidochelys kempii is the smallest species of sea turtle, measuring from 55 to 75 cm in length. Average length is 65 cm. Individuals weigh between 30 and 50 kg. The head and limbs (flippers) are non-retractile. The shell is streamlined, making this turtle extremely hyrdrodynamic. The carapace is a gray-olive color, whereas the plastron is an off-white to light yellow color.
Lepidochelys kempii has four limbs; two foreflippers and two hindflippers. The foreflippers power the turtle through the water while the hindflippers are used to steer and stabilize the turtle in the water. One to two claws are present on each foreflipper.
Ridleys have an upper eyelid for eye protection. As turtles, they lack teeth, and the jaw has a broad-beak shape. The external features of males and females do not differ until they reach maturity. Males are characterized by longer, thicker tails, and may have larger curved foreflippers. (Ernst and Barbour, 1972)
Some key physical features:
ectothermic ; heterothermic ; bilateral symmetry .
Sexual dimorphism: sexes shaped differently.
Development
Eggs are deposited on shore and incubate for an average of 55 days. Embryo development is temperature dependent. Lower nest temperatures tend to produce more males, whereas higher temperatures tend to produce more females.
Hatchlings uses a caruncle (temporary tooth) to break open the egg. After a hatchling escapes from the egg, it may take 3 to 7 days to crawl to the surface of the beach. Hatchlings emerge from the sand at night and immediately crawl towards the water. To locate the sea, hatchlings apparently orient themselves toward the greater light intensity reflected off the water. There may also be an internal magnetic compass that directs them to the water. After an individual hatchling enters the water, it goes into a “swim frenzy” for 24 to 48 hours. The hatchling swims into deeper water that protects it from predators.
The first year of life is spent away from shore. This year is dubbed the “lost year” because individuals in this age class are rarely seen near costal regions.
Lepidochelys kempii takes 11 to 35 years to reach maturity. (U.S. National Park Service, 2003; Wilkinson, 2003)
Special features of growth:
temperature sex determination.
Reproduction
Females breed every two or three years, but can lay multiple clutches within a single breeding season.
The breeding season is from April to July.
Individuals of this species spend most of their lives in isolation, generally coming into contact with conspecifics only to mate and to nest.
Mating takes place in the water. Males use their long curved flippers and claws to grip a female during mating.
Females swim to shore in a congregation called a “arribada,” then nest on beaches near the Texas-Mexico border (Tamaulipas Mexico, Padre Island National Seashore). A female uses her foreflippers to dig a body pit which is deep enough for her carapace to be level with the surrounding sand. She then uses her hindflippers to dig the cavity into which the eggs will be deposited. After the eggs are deposited, the female fills in the egg cavity and body pit with her hindflippers and uses her plastron to erase markings of the nest.
The eggs are leathery and covered in mucus which protects them from breaking as they are laid. Females may spend two or more hours nesting.
Mating systems:
polygynandrous (promiscuous) .
Females nest every two to three years, and may lay between one and nine clutches per nesting season. Females lay between 50 and 200 eggs per clutch. The nesting season extends from April to July.
Both males and females are reported to reach sexual maturity between the ages of 11 and 35 years. (U.S. National Park Service, 2003)
Key reproductive features:
iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; oviparous .
Females invest energy in the production of eggs and the digging of the nest. However, after providing their eggs with some protection by burying them, females expend no further energy or effort in caring for their young. Young are independent from the time of hatching. (U.S. National Park Service, 2003; Wilkinson, 2003)
Parental investment:
pre-fertilization (provisioning, protecting: female); pre-hatching/birth (provisioning: female, protecting: female).
Lifespan/Longevity
Mortality for L. kempii is very high around the time of hatching. For individuals reaching adulthood, lifespan generally ranges from 30 to 50 years. ()
Behavior
This species is strongly adapted for swimming, spending nearly all of its life in the water. These turtles are migratory. Lepidochelys kempii spends most of its life in relative isolation. Social contact apparently occurs only during mating and nesting. The activity of these animals during days versus nights has not been well studied.
Home Range
Home ranges for individuals of this species have not been reported. ()
Key behaviors:
natatorial ; motile ; migratory ; solitary .
Communication and Perception
It is not known to what extent sea turtles communicate with one another. They make grunting noises which can be heard by other turtles, and apparently use these vocalizations to locate each other. Visual cues are probably important in identifying other members of their species, and some tactile communication undoubtedly occurs during mating. However, the bulk of communication in this species remains undescribed. (Scholastic and Inc., 1998; Scholastic and Inc., 2001)
Food Habits
Lepidochelys kempii feeds on floating crabs, mollusks, shrimp, jellyfish and some vegetation. The jaws of these turtles are shaped for crushing and grinding. (Ernst and Barbour, 1972)
Primary Diet:
omnivore .
Animal Foods:
mollusks; aquatic crustaceans; cnidarians.
Plant Foods:
algae; macroalgae .
Predation
- tiger sharks ( Galeocerdo cuvier)
- herons
- seabirds
- killer whales (Orcinus orca)
- humans (Homo sapiens)
- raccoons (Procyon lotor)
Lepidochelys kempii is most vulnerable as a hatchling crawling from the nest to the shore. The slow-moving hatchlings make easy targets for herons, dogs, raccoons, and a variety of seabirds. The primary predatory threat to adults comes from sharks, especially the tiger sharks. Killer whales have also been known to consume sea turtles.
Human interference with nesting behavior may facilitate predation, and act as a barrier to this species. Lights around nesting areas confuses hatchlings about which way to crawl, sometimes causing them to crawl away from the water. Trash and noise can cause females to turn around from the nesting beach and back into the water, preventing deposition of eggs. The turtles are also hunted illegally to harvest meat. The shells can be made into combs and eyeglass frames. Eggs are also illegally collected because it is believed they have an aphrodisiac effect. (Ernst and Barbour, 1972)
Ecosystem Roles
Sea turtles have no significant economic role. Eggs and turtles were harvested in the past for reasons outlined under "Predation", but the harvesting of turtles or their eggs is now illegal. ()
Economic Importance for Humans: Negative
There is no known direct economic importance for humans. ()
Economic Importance for Humans: Positive
As a result of illegal harvesting, sea turtle meat may be eaten, and shells be made into combs or eyeglass frames. The eggs of L. kempii are believed to have an aphrodisiac effect. ()
Ways that people benefit from these animals:
food ; body parts are source of valuable material; source of medicine or drug .
Conservation Status
IUCN Red List: [link]:
Critically Endangered.
US Federal List: [link]:
Endangered.
CITES: [link]:
No special status.
Lepidochelys kempii is currently listed as endangered by the United States Fish and Wildlife Service and IUCN.
For More Information
Find Lepidochelys kempii information at
Contributors
Zachary Klug (author), Kalamazoo College. Ann Fraser (editor, instructor), Kalamazoo College.
Nancy Shefferly (editor), Animal Diversity Web Staff.
