Over 65 million years ago, leatherback sea turtles swam the oceans while on land, dinosaurs were dying out. Today, leatherbacks are in danger of meeting the same fate!

III. Physical Characteristics.

     A. Size.
         Adult males and females are equal in size.
           1. Green sea turtles reach about 31-44 in. and 150-410lb.
               The largest individual collected was 5 ft.  871 lb.
           2. Black sea turtles reach about 23-46 in. and 93-278 lb.
           3. The Kemp's ridley and olive ridley are the smallest species, and reach
               about 22-30 in. and 66-110 lb.

          4. Loggerheads reach about 32-41 in. and 146-223 lb.
          5. Hawksbills reach about 21-45 in. and 60-190 lb.
          6. Flatbacks reach about 32-38 in. and 132-185 lb.
          7. The leatherback is the largest of all living sea turtles.
              Mature leatherbacks reach about  4-6 ft.  441-1,116 lb.
             The largest leatherback recorded was 2,019 lb.
B. Body shape.
    Sea turtles are characterized by a large, streamlined shell and nonretractile head
    and limbs.
C. Coloration.
    1. Depending on the species, sea turtles range in color.
        They may be olive-green, yellow, greenish-brown, or black.
    2. The green sea turtle gets its name from the color of its body fat.
D. Flippers.
    1. A sea turtle cannot retract its limbs under its shell as a land turtle can.
    2. Flippers are adapted for swimming. Sea turtles are awkward and vulnerable on land.
    3. Foreflippers are long and paddlelike.
        a. Long digits are fused throughout the flipper.
        b. Only one or two claws are present on each foreflipper.
        c. A sea turtle swims with powerful winglike beats of its foreflippers.
    4. Hind flippers serve as rudders, stabilizing and directing the animal as it swims.
        The hind flippers of some species are quite dexterous in digging nests in the sand.
E. Head.
    1. A sea turtle cannot retract its head under its shell as a land turtle can.
    2. Sea turtles have large upper eyelids that provide protection for their eyes.
    3. Sea turtles do not have an external ear opening.
    4. Like other turtles, sea turtles lack teeth. Jaw shape varies among species.
        Each species has a jaw shape adapted for its diet.
F. Shell.
   1. The large, bony shell provides protection from predation and abrasion.
   2. In all species except the leatherback, the shell is covered with a layer of horny
        plates called scutes.
       a. Scutes are firm but flexible, not brittle.
       b. Scientists can identify sea turtle species by the number and pattern of scutes.
       c. The leatherback turtle has a thick and oil-suffused skin, which is an excellent
           insulator allowing this species to venture into colder waters.
  3. The dorsal (top) side of the shell is called the carapace.
       a. Depending on species, the adult carapace ranges in shape from oval to
           heart-shaped.
       b. In all species except the leatherback, the bony shell is composed of broadened,
           fused ribs, and the backbone is attached to the carapace.

     c. The leatherback's carapace is composed largely of cartilage raised into prominent
         logitudinal ridges. A layer of thoursands of small dermal bones lies just below the
         leathery skin.
  4. The ventral (bottom) side of the shell is called the plastron.
G. Sexual dimorphism.
  1. Male and female sea turtles do not differ externally until they approach maturity.
  2. Adult males have longer, thicker tails, because the male reproductive organ is
      housed in the base of the tail. In males, the tail may extend beyond the hind flippers.
  3. On some species, the claws on the foreflippers of males are elongated and curved,
      which may help in grasping the females' shells during mating.

A. Hearing.
    Like other reptiles, the sea turtle ear has a single bone in the middle ear that
    conducts vibrations to the inner ear. Researchers have found that sea turtles respond
    to low frequency sounds and vibrations.
B. Eyesight.
     1. Sea turtles can see well under water but are shortsighted in the air.
     2. Under experimental condititons, loggerhead and green sea turtle hatchlings
         exhibited a preference for near-ultraviolet, violet, and blue-green light.
C. Tactile.
     A sea turtle is sensitive to touch on the soft parts of its flippers and on its shell.
D. Taste.
     Little is known about a sea turtle's sense of taste.
E. Smell.
    1. Most researchers believe that sea turtles have an acute sense of smell in the water.
        Experiments show that hatchlings react to the scent of shrimp. This adaptation
       allows sea turtles to locate food in murky water.
    2. Sea turtles open their mouths slightly and draw in water through the nose, then
        immediately empty it out again throught the mouth. Pulsating movements of the
        throat are thought to be associated with smelling.

A. Swimming.
    1. Sea turtles are strong swimmers. The cruising speed for green sea turtles is
        about 1.5 to 2.3 kph(0.9-1.4 mph). Leatherbacks have been recorded at speeds
        of 1.5 to 9.3 kph (0.9-5.8 mph).
    2. Forelimbs are modified into long, paddle-like flippers for swimming.
    3. Neck and limbs are nonretractile. The shell adaptations necessary for retractile
        extremities would impede rapid swimming.

A sea turtle swims with powerful winglikes beats of its foreflippers.

B. Diving.
    1. Sea turtles are excellent divers. Leatherbacks routinely dive more than
        305 m (1,000 ft.), and theymay reach depths of more than 1,190 m (3,900 ft.)
        seeking jellyfish.
    2. Since they are ectothermic, sea turtles have a slow metabolic rate. This slowed
        metabolism allows them to stay submerged for long periods of time.
        a. Hawksbill turtles have been known to remain submerged for 35 to 45 minutes.
        b. Green sea turtles can stay under water for as long as five hours. Their heart
             rate slows to conserve oxygen: nine minutes may elapse between heartbeats.
        c. In the north-central Gulf of California, black sea turtles return each year to
             specific areas.  They bury themselves under water in sand or mud and may
            remain dormant from November to March.
    3. During long dives, blood is shunted away from tissues tolerant of low oxygen
        levels toward the heart, brain, and central nervous system.
    4. Leatherbacks have high concentrations of red blood cells; therefore, they can retain
        more oxygen.  The muscle of leatherbacks has a high content of the oxygen-binding
        protein myoglobin. Myoglobin transports and stores oxygen in muscle tissue.
C. Respiration.
     In studies conducted on green sea turtles, lung capacity exchange in one breath
     exceeded 50%.
D. Salt secretion.
     1. Sea turtles can live in seawater with no need for a freshwater source. They obtain
         sufficient water from their diet and from metabolizing seawater.
     2. Like other marine reptiles and seabirds, sea turtles have a salt gland to rid their
         bodies of excess salt. This gland empties in the sea turtles' eyes. The secretion of
         salt and fluid makes them look as if they are "crying" when they come ashore.
         These "tears" help keep the eyes free of sand while females dig their nests.
E. Sea turtles on land.
    1. For the most part, the only time sea turtles need to leave the sea is when females
        haul out to lay eggs; however, on uninhabited or sparsely-inhabited beaches, turtles
        have been observed basking on land.
    2. Many adaptations that make sea turtles successful in the sea make them slow and
        vulnerable on land.

A. Food preferences and resources.
    Diet varies with species. Sea turtles may be carnivorous (meat eating), herbivorous
    (plant eating), or omnivorous (eating both meat and plants). The jaw structure of many
    species indicates their diet.
     1. Green and black sea turtles have finely serrated jaws adapted for a vegetarian diet
         of sea grasses and algae. In adulthood, they are the only herbivorous sea turtles,
         but in an aquarium environment all sea turtle species can be maintained on a
         carnivorous diet.
     2. Loggerheads' and ridleys' jaws are adapted for crushing and grinding. Their diet
        consists  primarily of crabs, mollusks, shrimps, jellyfish, and vegetation.
     3. A hawksbill has a narrow head with jaws meeting at an acute angle, adapted for
        getting  food from crevices in coral reefs. They eat sponges, tunicates, shrimps,
        and squids.
     4. Leatherbacks have delicate scissorlike jaws that would be damaged by anything
         other than their normal diet of jellyfish, tunicates, and other soft-bodied animals.
        The mouth cavity and throat are lined with papillae (spinelike projections) pointed
        backward to help them swallow soft foods.
     5. Researchers continue to study the feeding habits of flatbacks. There is evidence
         that they  are opportunistic feeders that eat seaweeds, cuttlefish, and sea
         cucumbers.
B. Eating habits.
     Some species change eating habits as they age. For instance, green sea turtles are
     mainly carnivorous from hatchling until juvenile size; they then progressively shift to
     an herbivorous diet.

A loggerhead's jaws are adapted for crushing and grinding (left).
A leatherback's delicate jaws would be damaged by anything other than soft-bodied animals (right).

A. Sexual maturity.
     Researchers are still studying sexual maturity in sea turtles.
      1. Estimates of sexual maturity in sea turtles vary not only among species, but also
          among different populations of the same species. Maturity may range from as
          early as three years in hawksbills; 12 to 30 years in loggerheads; to 20 to 50 years
          in green sea turtles.
      2. Sexual maturity often is related to carapace size. Studies have shown that
          hawksbills reached sexual maturity at a carapace size of 60 to 95 cm (24-37 in.);
          loggerheads reached maturity at a carapace size of 79 cm (31 in.); and green sea
          turtles reached maturity at 69 to 79 cm (27-31 in.).
     3. Evidence suggests that some turtles continue to grow after reaching sexual
         maturity, while some stop growing after reaching maturity.

Mating activity.
    1. For most species, courtship activity usually occurs several weeks before the
        nesting season.
    2. Two or more males may court a single female.
    3. Males have enlarged claws on their front flippers. These aid males in grasping the
        shells of the females during mating.
    4. Fertilization is internal. Copulation takes place in the water, just offshore.
C. Nesting behavior.
    1. Like other turtles, sea turtles lay eggs. They must come ashore to do so.
    2. Females nest a few weeks after mathing.
    3. Depending on the species, sea turtle nesting follows a set pattern.
      a. Females usually nest during the warmest months of the year. The exception
          is the leatherback turtle, which nests in fall and winter.
      b. Most females return to the same nesting beach each year. Recent studies
          suggest that some females of some species will visit more than one nesting
          beach in a season.
      c. Females of most species usually come ashore at night, alone, most often during
          high tide. A female sea turtle crawls above the high tide line and, using her front
          flippers, digs out a "body  pit." Then using her hind flippers, she digs an egg cavity.
         The depth of the cavity is determined by the length of the stretched hind flipper.
     d. Depending on the species, the female deposits 50 to 200 Ping Pong ball-shaped
         eggs into the egg cavity. The eggs are soft-shelled, and are papery to leathery in
         texture. They do not break when they fall into the egg cavity. The eggs are
         surrounded by a thick, clear mucus.
    e. The female covers the nest with sand using her hind flippers. Burying the eggs
        serves three  purposes: it helps protect the eggs from surface predators; it helps
        keep the soft, porous shells moist, thus protecting them from drying out; and it helps
        the eggs maintain proper temperature. Experts can identify the species of turtle by
        the type of mound left by the nesting female and by her flipper tracks in the sand.
     f. Females may spend two or mroe hours out of the water during the entire nesting
        process.
     g. Females usually lay between one and nine clutches (groups) of eggs per season.
     h. It is possible that through the storage of sperm from one or several males in the
         oviducts of  the females, all clutches of the current nesting season may be fertilized
         without repeated  matings.
     i. Females may nest every two to three years.
 3. The Kemp's ridley and olive ridley form masses called arribadas
     (Spanish for "arrival").
     Arribadas contain thousands of egg-bearing females that come ashore at the same
     time to lay eggs.

A. Incubation.
    1. Incubation time varies with species, clutch size, and temperature and humidity in the
        nest.
    2. The incubation time for most species is 45 to 70 days.
    3. Research indicates that the sex of an embryo is determined sometime after
        fertilization, as the embryo develops, and may be temperature dependent. Lower
        nest temperatures produce more males; higher temperatures produce more females.
B. Hatching.
    1. Sea turtles hatch throughout the year but mostly in summer.
    2. Hatchlings use a caruncle (temporary egg tooth) to help break open the shell.
    3. After hatching, the young turtles may take three to seven days to dig their way
        to the surface.
    4. Hatchlings usually wait until night to emerge from the nest. Emerging at night
        reduces exposure to daytime predators. They leave the nest and head to the
        water in groups. Studies have shown that some nests will produce hatchlings
        on more than one night.
C. Reaching the ocean.
     1. There are several theories as to how htachlings find the sea.
        a. Hatchlings may discriminate light intensities and head for the greater
            light intensity of the open horizon.
        b. During the crawl to the sea, the hatchling may set an internal magnetic compass,
            which it  uses for navigation away from the beach.
    2. When a hatchling reaches the surf, it dives into a wave and rides the undertow out
        to sea.
     a. A "swim frenzy" of continuous swimming takes
     place for about 24 to 48 hours after the hatchling
     enters the water.
     b. This frantic activity gets the young turtle into
     deeper water, where it is less vulnerable to
     predators.
     c. There have been reports of swimming hatchlings diving straight down when birds
        and even airplanes appear overhead. This diving behavior may be a behavioral
        adaptation for avoiding predation by birds.
D. The first year.
     1. During the first year, many species of sea turtles are rarely seen. This first year is
         known as the "lost year."
     2. Researchers generally agree that most hatchlings spend their first few years living
         an oceanic existence before appearing in coastal areas. Although the migratory
         patterns of the young turtles during the first year has long been a puzzle, most
         researchers believe that they ride prevailing surface currents, situating themselves
         in floating seaweed where they are camouflaged and where they can find food.
     3. Research suggests that flatback hatchlings do not go through an oceanic phase.
         Evidence showsthat the young turtles remain inshore following the initial swim
         frenzy. Most remain within 15 km(9.3 miles) of land.

     2. Fishes, dogs, seabirds, raccoons, ghost crabs, and other predators prey on
         eggs and hatchlings. Most than 90% of hatchlings are eaten by these predators.
     3. Flatback turtle nests are susceptible to predation by monitor lizards, dingoes,
         and introduced foxes.
D. Fibropapillomas.
     Green sea turtles are black sea turtles may develop lobed tumorlikegrowths
     (fiborpapillomas) on the skin. These growths can result in reduced vision,
     obstruction of normal swimming and feeding, and increased susceptibility to
     secondary parasitism and infection.
E. Human impact.
     1. Nesting areas are becoming scarce due to beach development and disturbances.
         Kemp's ridleys only nest on one beach in the entire world: on a remote beach in
         Mexico near the village of Rancho Nuevo (about 161 km, or 100 miles, south of
         the Texas border). In 1947, scientists witnessed an arribada of more than 40,000
         Kemp's ridley turtles in one day. In the 1960s, numbers were reduced to less than
         5,000 turtles. In 1973, the largest arribada contained only 200 individuals.
    2. Although the population of olive ridley sea turtles is the most abundant in the world,
        their major nesting beach at Gahirmatha in Orissa, India is in jeopardy. The
        Government of India is planning to develop a major fishing port and processing
        plant 10 km (6.2 miles) from the critical nesting beach.  More sea turtles nest on
        this beach than on any other beach in the world.
    3. Nesting females and hatchlings are disturbed by the presence of trash on nesting
        beaches. If trash impedes its crawl up the beach, a female returns to the sea instead
        of nesting.
   4. The noise and activity of people on the beach also may cause females to return to the
        sea instead of nesting.
   5. Some sea turtles die when they ingest trash. Leatherbacks are especially susceptible
       to ingesting plastic, mistaking it for jellyfish.
   6. Thousands of sea turtles drown in shrimp nets each year. Sea turtles forage in waters
       where commercial shrimpers trawl. In 1947, 5,000 U.S. shrimping trawlers worked in
       the Gulf of Mexico.  That number increased to 15,000 full-time and 40,000 part-time
       trawlers by 1989.
7. Artificial lighting on beaches may misrepresent the time of day to turtles attempting to
    nest. Most turtles are noctural nesters, and to a turtle that has not yet come ashore to
    nest, a brightly lighted beach may signify daylight and inhibit nesting.
8. Hatchlings can become disoriented by city and street lights when trying to find the surf.
    Many young turtles actually head away from the ocean and toward parking lots. These
    animals may be eaten by predators or crushed by cars. Some die from exposure.
9. Some people illegally collect turtle eggs for food and for their alleged aphrodisiac
    effect.
10. Sea turtles are hunted (illegally in this country and in some cases legally elsewhere)
      for their meat and shells, which are used to make combs, eyeglass frames,
      aphrodisiacs, and curious. The fat of green sea turtles, boiled with cartilage called
      calipee, made a popular soup, which led to the decline in green sea turtle population
      numbers.
11. Deforestation may indirectly threaten sea turtle nests. Costa Rica has one of the
      highest deforestation rates in the world. Some researchers fear that without the
     forest to draw up ground water, the water table will rise beneath the beaches and
    drown nests.

12. Propeller and collision injuries from boats are not uncommon. These types of injuries
      are more frequent in areas with a high level of recreational boating, such as South
      Florida, the Florida Keys, and the United States Virgin Islands.

A. Legal protection for sea turtles.
     1. All eight species of sea turtles are listed as threatened or endangered on the U.S.
         Endangered and Threatened Wildlife and Plants List. It is illegal to harm, or in any
         way interfere with , a sea turtle or its eggs.
      2. The Convention on International Trade in Endangered Species of Wild Fauna and
          Flora (CITES) is an international treaty developed in 1973 to regulate trade in
          certain wildlife species. CITES protects all species of sea turtles. The U.S. and 115
          other countries have banned the import or
          export of sea turtle products.
B. Turtle Excluder Device.
     1. At a cost of millions of dollars, the National Marine Fisheries Service developed
         the Turtle Excluder Device (TED).
     2. The TED is a small, metal grid trapdoor inside a trawling net that allows shrimp to
         pass to the back while the turtles escape to safety before becoming entrapped or
         entangled.
     3. Since 1989, federal law requires that this device be installed on the nets of all U.S.
         fishing trawlers working in areas populated by sea turtles.
C. Protecting nests.
    1. Nests can be protected from predators by placing screens over them. Eggs laid
        too close to the water or in erosion zones can be relocated to safer areas.
    2. In a bold conservation program, the townspeople of a small Costa Rican village are
        allowed to gather eggs laid during the first two nights of each olive ridley arribada.
        Scientists have calculated that a controlled harvest would leave enough protected
        eggs to rejuvenate the population (in one nesting season, 20 to 30 million olive ridley
        eggs may be laid in this beach village) while allowing villagers to maintain a
        livelihood. The program has the potential to stop poachers of other eggs on
        other beaches by keeping the prices of the "legal" eggs too low for poachers to
        compete.
D. Lighting.
     Although eliminating beach lighting would be the most effective way to reduce
     disorientation of hatchlings, studies have shown that low pressure sodium vapor
     lights have a lesser effect on loggerhead and green sea turtle hatchlings. Many
     beach communities have encouraged the use of these lights.
E. Wildlife refuges.
    1. Legislation is underway to allocate government funding for the Archie Carr
       National Wildlife Refuge on the east coast of Florida, between Melbourne Beach
       and Vero Beach. Full protection of the refuge would cost a total of $90 million dollars,
        of which $50 million would come from state and local sources. As of 1994, federal
        funding has reached $7 million.
      a. This 33-km (20.5 mile) section of beach is the most important nesting site for
           loggerheads in the Western Hemisphere.
       b. The refuge is the most important nesting beach in the United States for the
           green sea turtle.
      c. The refuge also is considered prime real estate for commercial development,
          making government funding essential to its preservation.
   2. The governments of Nicaragua and Costa Rica have established, and are striving
        to expand, national parks and biological reserves where sea turtles forage and nest.
       Tortuguero, Costa Rica maintains the largest green sea turtle rookery in the
       Caribbean. Local economics is no longer based on turtle harvests, but on tourism.
       More than 15,000 visitors are expected each year.
F. Managing sex ratios.
    Most conservationists believe that abundant nesting females are desirable to
    rejuvenate sea turtle populations. Researchers with Reproductive Sciences, Inc. and
    Reptile Conservation International have developed, and are patenting, a technique of
    applying an estrogen solution onto eggs to produce a higher number of females under
    normal incubation.
G. In zoological environments.
     1. Having sea turtles at marine zoological parks provides an opportunity for the public
         to learn, up-close, about these animals and how human activities may impact their
         survival.
     2. In the protected environment of a marine zoological park, scientists can examine
         aspects of sea turtle biology that are difficult or impossible to study in the wild.
     3. Sea World of Florida treats numerous green and loggerhead sea turtles each year.
         a. Sea turtles often are brought in after a cold weather snap. Low water
             temperatures cause a sea turtle's metabolism to slow - the hypothermic turtles
             become sluggish and are unable to feed. marine patrol officers may find the
             turtles floating at the surface of the water in a
            semi-dormant state.
        b. In December 1989, 95 hypothermic green sea turtles were rescued from Florida's
           Merritt Island. These turtles were housed in recovery pools at Sea World of
           Florida for about 10 weeks. Once the weather warmed up, the turtles were released
           in the same area that they  were rescued.
        c. Sea World has rescued other sea turtles with injuries resulting from entanglement,
           motorboat collisions, ocean dredging, or ingestion of non-food items.
   4. Data gathered through the Sea World Animal Rescue and Rehabilitation Program
       and similar programs can help scientists more accurately assess and recommend sea
       turtle population management programs in the wild.

This is difficult to answer because we don't fully understand all the relationships between different animals and plants in the ocean. Turtles are a natural part of the environment and if they were to disappear it would upset the balance which has existed for millions
of years.

No. None of the sea turtles have the exact same DNA, unless they are identical twins. However, if you compare the DNA patterns of the different turtles you can tell which ones are related to each other. As with all species, the baby turtles have DNA patterns that
closely resemble that of their parents and so on. Some of the eggs that have been laid by the turtles here are particularly large, and it may be possible that there are twins in these eggs but we won't know for sure until after they have hatched.

A leatherback turtle is very large, so its size also provides some protection. They are also able to change direction very quickly in the water, so they can avoid predators that way too.

The entire nesting process lasts about two hours. This is from the time that the female emerges from the water to the time that she returns to the sea. Once she finally gets to a nesting spot, it takes her about 20  minutes with her front flippers to dig a pit for her body. It  takes another 20 minutes or so to dig the nest chamber  with her rear flippers.
When the hole has been dug as deep as her flippers will reach, she starts to lay the eggs. This takes about 20 minutes. 'Camouflaging' or covering up the nest may take an additional 15 or 20 minutes.

Turtles must lay their eggs on land and they are safest if buried away from predators. The sand or earth provides an insulated and stable environment for eggs to incubate.

The jaws of a leatherback turtle have scissor-like edges which assist in cutting soft prey. Its throat is lined with long spines pointed backwards to keep squishy prey from escaping while expelling excess water. Different species of sea turtles eat different kinds of food and their jaws are specially adapted to their diets.

A graduate student here is doing a genetic study with blood samples to learn about the reproductive biology of the turtles. She's finding out whether the hatchlings from the same mother all have the same father. Blood can also provide information about hormones and  biochemistry of the turtles.

In general most Costa Ricans want to preserve their environment and are supportive of conservation programs. Some people have different ideas on what is the best way to do this but still have the same general goal. There is pressure though from some tourism-based industries that see conservation work as obstructing the opportunities for business.

We don't know for sure if turtles communicate, but we think they can probably communicate by sound with each other under water.

The number of eggs that survive varies, but usually 50 to 70 percent of the eggs hatch. However, last year only 8 percent of the eggs hatched at Playa Grande due to  flooding from unpredictably high tides.  Hatching success varies from season to season and between individual females. The success rate is influenced by the condition the eggs are in when the embryo is developing. For example, the temperature and moisture levels of the sand play an important role.

Poachers can sell the eggs at high prices.

The turtles comes up to the surface of the water to breathe. They take several quick breaths before they dive in again.

So far this season at Playa Grande, the largest turtle is 160 cm long by 123 cm wide. She came up on the beach on the night of Oct. 31 to nest. The average turtle size in 1997 was 145cm and the minimum was 129 cm.

Sea turtles have been recorded as diving to more than 1,400 meters (4/5 miles). They have several special adaptations which allow them to stay under water for around one hour.

The males are slightly larger and have a longer tail, otherwise they look the same. Only sexually mature males have a longer tail -- when the turtles are young it is impossible to tell them apart. It is more difficult to study males as they do not come out of the water. Most studies have focused on nesting females.

People sell the turtle eggs to be used in cooking. Their blubber is also used for various oil products -- lamp oil, skin lotions. Leatherback meat is not supposed to taste good, so they are not generally killed to eat.

A nesting female lays about 60-70 large, pool-ball-sized eggs and around 30 smaller eggs. The small eggs have no yolk in them, and so no hatchling develops. We are not completely sure what role the small eggs play.

The lights on a beach at night and the noise and activity of people can cause a nesting female to return to the water before she lays her eggs or even keep her from coming up on the beach at all.

The main reason the species is close to extinction is because of human activity, such as beachside development, discarding of debris into the ocean, poaching of eggs, and capture by fishing vessel.

The hatchlings are about 75 to 85 mm long when measured along the shell. They weigh about 50 grams.

The appearance of the turtle's shell is what gives them the name 'leatherbacks.' The shell looks like leather. It is actually a layer of thin, tough, rubbery skin. The  leatherback is the only turtle without a hard shell.

It is difficult to tell most leatherback turtles apart. There is a pink spot on the turtle's head unique to each individual. Flippers may be scarred or missing, or there may be evidence of shark bites. The way biologists identify different turtles is to use an electronic microchip tag like the ones used to identify dogs and cats. This is put into the muscle of the shoulder and is read with a small scanner.

Many turtles are endangered and are going extinct because of the pet trade. So it is important to find out as much information as possible about the kind of turtle that you want. Is the turtle endangered or restricted?
Go to the library, talk to people who own turtles, join a club. The easiest turtle to have as a pet is the slider turtle, but they also frequently carry salmonella, a bacteria that can make you very sick. Turtles such as Chinese box turtles make good pets, but they can get very big. Turtles have very different requirements. They eat different things, need different kinds of spaces. It also takes a lot of work to keep them clean.

No, we don't use a spotlight. Actually the hatchlings are safest from natural predators when they are under the cover of darkness.

I find sea turtles to be very mysterious animals. They lead secret lives, which lead to great opportunities of discovery. I am also interested in learning about how marine animals are able to dive to such great depths.

Kemp's Ridley is the most endangered sea turtle.

That's a hard question to answer. We estimate that leatherbacks are sexually mature when they are less than 10 years old, and we think that they may live to be  40 or 50 years old.

As turtles grow, their shells grow along the edge of the scutes (the square parts). Sometimes thin lines can be seen which indicate age -- like the rings of a tree.

The males are slightly larger. They have a tail that is 3 to 4 times longer than females. Otherwise there are few differences. It is more difficult to study the males as they do not come out of the water. Most studies have focused on nesting females.

One theory is that they navigate by the magnetic field.  They may also use imprinting, where their sense of smell and taste guides them.

Water is the natural habitat of leatherbacks. The nesting females are not able to stay on land for long.  They will overheat. They can stay on land up to about four hours.