Animal Diversity Web

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. (U.S. Na­tional Park Ser­vice, 2003; ; Ernst and Bar­bour, 1972; 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)

• Habitat Regions
• tropical
• saltwater or marine

• Aquatic Biomes
• coastal

Phys­i­cal De­scrip­tion

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)

• Other Physical Features
• ectothermic
• heterothermic
• bilateral symmetry

• Sexual Dimorphism
• sexes shaped differently

• Range mass

  30 to 50 kg

  66.08 to 110.13 lb

• Range length

  55 to 75 cm

  21.65 to 29.53 in

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)

• Development - Life Cycle
• temperature sex determination

Re­pro­duc­tion

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 System
• 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

• Breeding interval

  Females breed every two or three years, but can lay multiple clutches within a single breeding season.

• Breeding season

  The breeding season is from April to July.

• Range number of offspring

  50 to 200

• Average number of offspring

  110

  AnAge

• Average gestation period

  55 days

• Average gestation period

  60 days

  AnAge

• Range age at sexual or reproductive maturity (female)

  11 to 35 years

• Range age at sexual or reproductive maturity (male)

  11 to 35 years

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. ()

• Typical lifespan
  Status: wild

  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.

• Key Behaviors
• natatorial
• motile
• migratory
• solitary

Home Range

Home ranges for in­di­vid­u­als of this species have not been re­ported. ()

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, Inc., 2001; Scholas­tic, Inc., 1998; Scholas­tic, Inc., 2001; Scholas­tic, Inc., 1998; Scholas­tic, Inc., 2001; Scholas­tic, Inc., 1998)

• Communication Channels
• visual
• tactile
• acoustic

• Perception Channels
• visual
• tactile
• acoustic
• magnetic

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

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)

• Known Predators

  • tiger sharks ( Galeocerdo cuvier)
  • herons
  • seabirds
  • killer whales (Orcinus orca)
  • humans (Homo sapiens)
  • raccoons (Procyon lotor)

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: 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. ()

• Positive Impacts
• food
• body parts are source of valuable material
• source of medicine or drug

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

There is no known di­rect eco­nomic im­por­tance for hu­mans. ()

Con­ser­va­tion Sta­tus

Lep­i­dochelys kem­pii is cur­rently listed as en­dan­gered by the United States Fish and Wildlife Ser­vice and IUCN.

• IUCN Red List

  Critically Endangered
  More information

• IUCN Red List

  Critically Endangered
  More information

• US Federal List

  Endangered

• CITES

  No special status

Con­trib­u­tors

Zachary Klug (au­thor), Kala­ma­zoo Col­lege, Ann Fraser (ed­i­tor, in­struc­tor), Kala­ma­zoo Col­lege, Nancy Shef­ferly (ed­i­tor), An­i­mal Di­ver­sity Web.

Ref­er­ences

Ernst, C., R. Bar­bour. 1972. Tur­tles of the United States. Lex­ing­ton, Ken­tucky: The Uni­ver­sity Press of Ken­tucky.

Scholas­tic, Inc., 2001. "Meet Dr. Frank Pal­adino" (On-line). Ocean Life. Ac­cessed No­vem­ber 13, 2005 at http://​teacher.​scholastic.​com/​activities/​explorer/​oceanlife/​main.​asp?​template=meet_​explorer&​article=interview_​frank.

Scholas­tic, Inc., 1998. "Meet Dr. Richard Reina" (On-line). Ocean Life. Ac­cessed No­vem­ber 13, 2005 at http://​teacher.​scholastic.​com/​activities/​explorer/​oceanlife/​main.​asp?​template=meet_​explorer&​article=interview_​reina.

U.S. Na­tional Park Ser­vice, 2003. "Kemp's ri­d­ley nest­ing." (On-line). Na­tional Parks (Padre Is­land Na­tional Seashore). Ac­cessed Au­gust 04, 2006 at http://​www.​nps.​gov/​pais/​website/​kemp's_ri­d­ley.htm.

Wilkin­son, T. 2003. The rid­dle of ri­d­ley's.. Na­tional Parks, 77: 26-29.