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Sea Turtles in the Classroom: A Model for Science Education Presented by Karen M. Klein, M.S., Ph.D. student Drexel University, Philadelphia, PA USA Drexel University Study turtles in the city, you ask?!? Drexel University Drexel University is home of the Center for Biodiversity and Conservation Graduate students from the United States and the world are doing research in areas all over the globe Drexel University Professors at Drexel’s Center for Biodiversity and Conservation have decades of years of experience and hundreds of publications in the field of turtle biology, ecology, and conservation! Current Research The Leatherback Trust, founded in 1988 by Drexel University professor Dr. James Spotila, currently has an active leatherback sea turtle conservation and education program in Las Baulas, Costa Rica Current Research Drexel students, as well as students from other Universities and Earthwatch volunteers, carry out an extensive research program on Costa Rica’s population of Leatherback sea turtles These efforts include movement studies, nesting studies, and hatchling studies Current Research Research on turtles in not confined to marine turtles, however Current Research Dr. Hal Avery and his graduate students have been conducting a long term population study of the threatened desert tortoise, Gopherus agassizii, in the Mojave desert Current Research Barbara Bell has dedicated her doctoral research to studying the effects of a recent oil spill on hatchling and adult snapping turtles (Chelydra serpentina) in the John Heinz Refuge in Philadelphia Current Research Amanda Curtin has devoted her doctoral research to a osteological growth study of the desert tortoise Current Research Karen Klein and Bibi Tomillo, both doctoral students, are conducting a population biology study of red-bellied turtles (Pseudemys rubriventris) in the wetland areas within the Philadelphia Airport Current Research A large project run by Dr. Walt Bien at Warren Grove Range in the Pine Barrens, NJ includes research with population and conservation studies of mammals, reptiles, plant species, and fire ecology Introduction Of all animals, the humble turtle seems to capture the imagination and wonder of children of all ages the most Introduction Turtles have found themselves a part of popular culture Who can forget Yertle and the Art of Turtle Stacking?? Introduction Even as adults, most of us remain fascinated by these animals Their protective shells are of curiosity and their ancient-like demeanor make them especially endearing Introduction In a recent poll of freshman Biology students (non majors), 95% of them said they think turtles are very interesting animals The fascination with turtles transcends all ages, backgrounds and cultures Introduction Whether revered as a cultural and spiritual icon or just thought to be “cool”... Just about everybody likes turtles!!! Introduction This interest in the organism itself can be used as an advantage to today’s classroom educator Turtles, like many animals, are an important part of our ecosystem, and are greatly affected by current issues like habitat loss and pollution In this way, turtles can be incorporated into many concepts in science, and therefore be used as a tool to fulfill your New Jersey Core Curriculum Content Standards for science Introduction Sea turtles are ancient creatures. They have traveled our planet for more than 200 million years, tracing a highly successful evolutionary path, living in a variety of environments from dry land to the open sea. This makes them fascinating, albeit tough, subjects to study. Introduction Of the 16 Orders of reptiles that evolved during the last 310 million years, that of the Testudines, or turtles, is one of only four that remain today The three other Orders are Crocodilia, Squamata, and Rhyncocephala (Tuataras). Introduction Turtles are distinctive because they live inside shells The top shell, over the back, is called the "carapace", and the shell on the bottom, over the belly, is called the "plastron In most turtles, the shell is made up of large bones, covered on the outside by large scales, known as "scutes". Introduction Turtles, terrapins and tortoises all belong to the Order Testudinata (also called Chelonia) Of the more than 220 species of living turtles, only 7 are marine Sea Turtles of the World Loggerhead (Caretta caretta) Characteristics: Named for its very large head and strong jaws; 32-41 inches long, up to 350 lbs Diet: primarily carnivorous, feeding on shellfish at the bottom of the ocean Habitat: Prefer to feed in coastal bays and estuaries, as well as in the shallow water along the continental shelves of the Atlantic, Pacific and Indian Oceans Loggerhead Range: worldwide Status: U.S. - Listed as Threatened; International Listed as Endangered Nesting: Nest at intervals of 2, 3, or more years. Nests between 4 to 7 times per season. Lays average of between 100 to 126 eggs in each nest. Green turtle (Chelonia mydas) Characteristics: Head is small; The carapace color varies from pale to very dark green and plain to very brilliant yellow; 3 feet in length, about 300-350 lbs Diet: mostly eat sea grass and algae, the only sea turtle that is strictly herbivorous as an adult Habitat: Mainly stay near the coastline and around islands and live in bays and protected shores. Rarely are they observed in the open ocean Range: Found in all temperate and tropical waters throughout the world. Status: U.S. - Listed as Endangered; International Listed as Endangered Nesting: Nest at intervals of 2, 3, or more years; Nests between 3 to 5 times per season; Lays an average of 115 eggs in each nest; largest nesting site in Western hemisphere: Tortugeuro, Costa Rica Leatherback (Dermochelys coriacea) Characteristics: Carapace is large, elongated and flexible with 7 distinct ridges running the length of the animal; composed of a layer of thin, tough, rubbery skin; to 8 feet in carapace length; 450 to 1,300 pounds Diet: Feed almost exclusively on jellyfish Habitat: Primarily found in the open ocean, as far north as Alaska and as far south as the southern tip of Africa. Known to be active in water below 40 degrees Fahrenheit, the only reptile known to remain active at such a low temperature. Range: Most widely distributed of all sea turtles; found world wide with the largest north and south range of all the sea turtle species Status: U.S. - Listed as Endangered; International - Listed as Critically Endangered Nesting: Nest at intervals of 2 to 3 years. Nests between 6 to 9 times per season. Lays an average of 80 fertilized eggs Flatback (Natator depressa) Characteristics: Carapace is oval or round and body is very flat; carapace is olive-grey with pale brown/yellow tones on margins and the flippers creamy white; up to 39 inches in carapace length; average of 198 pounds Diet: Apparently eats sea cucumbers, jellyfish, mollusks, prawns, bryozoans, other invertebrates and seaweed Habitat: Prefer turbid inshore waters, bays, coastal coral reef and grassy shallows Range: Most restricted range of all sea turtle species, limited to the coastal waters of the northwestern, northern and northeastern regions of Australia and the Gulf of Papua, New Guinea Status: Listed as Data Deficient Nesting: Nests 4 times per season. Lays an average of 50 eggs in each nest Hawksbill (Eretmochelys imbricata) Characteristics: Head is narrow, carapace is elliptical, orange, brown or yellow; 30 to 36 inches in carapace long; 100 to 150 pounds Diet: The hawksbill's narrow head and jaws shaped like a beak allow it to get food from crevices in coral reefs. They eat sponges, anemones, squid and shrimp Habitat: Typically found around coastal reefs, rocky areas, estuaries and lagoons Range: Most tropical of all sea turtles. Tropical and subtropical waters of the Atlantic, Pacific and Indian Oceans Status: U.S. - Listed as Endangered; International - Listed as Critically Endangered Nesting: Nest at intervals of 2, 3, or more years. Nests between 2 to 4 times per season. Lays an average 160 eggs in each nest Kemp’s ridley (Lepidochelys kempii) Characteristics: Head is moderate and triangular in size; adults have a dark grey green carapace with a white or yellowish plastron; adults measure 24 to 28 inches; between 77 and 100 pounds Diet: Have powerful jaws that help them to crush and grind crabs, calms, mussels, and shrimp. They also like to eat fish, sea urchins, squid and jellyfish Habitat: Prefer shallow areas with sandy and muddy bottoms. Range: Adults are mostly limited to the Gulf of Mexico Status: U.S. - Listed as Endangered; International Listed as Critically Endangered Nesting: Nest every year in arribadas. Nests about 2 times each season. Lays an average of 110 eggs in each nest Olive Ridley (Lepidochelys olivacea) Characteristics: Head is quite small; named for its olive green colored shell; Adults measure 24 to 28 inches; between 77 and 100 pounds Diet: Have powerful jaws that help them to crush and grind crabs, clams, mussels, and shrimp. They also like to eat fish, sea urchins, squid and jellyfish Habitat: They typically forage off shore in surface waters or dive to depths of 500 feet (150 m) to feed on bottom dwelling crustaceans. Range: Live in tropical regions of the Pacific, Indian and Atlantic Oceans Status: U.S. - Listed as Threatened; International Listed as Endangered Nesting: Nest every year in arribadas. Nests 2 times each season. Lays an average of over 105 eggs in each nest Distribution and Habitat Sea turtles live inhabit all of the world’s oceans Adults of most species are found in shallow, coastal waters, bays, lagoons, and estuaries. Some also venture into the open sea. Migration Some sea turtle populations nest and feed in the same general areas; others migrate great distances. Migration habits differ among sea turtle species; migrations may range from a few to thousands of miles. Migration Green sea turtle populations migrate primarily along the coasts from nesting to feeding grounds Some populations will travel 1,300 miles across the Atlantic Ocean from the Ascension Island nesting grounds to the Brazilian coast feeding grounds Migration Loggerheads leave foraging areas and travel on breeding migrations that range from a few to thousands of miles Migration Leatherbacks have the longest migration of all sea turtles. They have been found more than 4,831 km (3,000 miles) from their nesting beaches Population Total population figures are often difficult to ascertain because juvenile and male sea turtles do not come ashore and are difficult to count. Population data are usually based on the numbers of adult females that come ashore to nest. Even then, the numbers are ambiguous some females nest every two to three years, some may nest more than once on the same beach in a season, and some females will visit more than one nesting beach in a season. Population The Kemp's ridley is the most endangered sea turtle In 1947, 92,000 nests were estimated. Surveys conducted between 1978 and 1988 indicated an average of about 800 nests per year The total number of nesting females may be as low as 350 on beaches where tens of thousands of Kemp's ridley used to nest Population U.S. population trends of loggerheads show a decline in nesting areas of Georgia and South Carolina No decline or a possible increase in southern Florida Atlantic areas. Size The Kemp's ridley is the smallest species, and reach about 22-30 in and 66-110 lb The leatherback is the largest of all living sea turtles. Mature leatherbacks reach about 4-6 ft. and 441-1,116 lbs The largest leatherback recorded was 2,019 lbs. Flippers Flippers are adapted for swimming; sea turtles are awkward and vulnerable on land. Foreflippers are long and paddle-like, swimming with powerful wing-like beats 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. Head and jaw A sea turtle cannot retract its head under its shell as a land turtle can. Like other turtles, sea turtles lack teeth. Jaw shape varies among species. Each species has a jaw shape adapted for its diet Head and jaw The jaw structure of many species indicates their diet Shell The large, bony shell provides protection from predation and abrasion Depending on species, the adult carapace ranges in shape from oval to heart-shaped; this allows the turtle to be streamlined as it swims through the water Shell In all species except the leatherback, the shell is covered with a layer of horny plates called scutes The leatherback turtle has a thick and oil-suffused skin, which is an excellent insulator allowing this species to venture into colder waters Diving Sea turtles are excellent divers. Leatherbacks routinely dive more than 1,000 ft., and they may reach depths of more than 3,900 ft. seeking jellyfish Hawksbill turtles have been known to remain submerged for 35 to 45 minutes; green sea turtles can stay under water for as long as five hours Sexual Maturity 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 Mating Activity For most species, courtship activity usually occurs several weeks before the nesting season Males have enlarged claws on their front flippers. These aid males in grasping the shells of the females during mating Fertilization is internal. Copulation takes place in the water, just offshore Nesting behavior Like other turtles, sea turtles lay eggs; they must come ashore to do so Females usually nest during the warmest months of the year. The exception is the leatherback turtle, which nests in fall and winter Most females return to the same nesting beach each year Nesting behavior 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 Nesting behavior 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 Nesting behavior 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 Females may spend two or more hours out of the water during the entire nesting process Nesting behavior Females usually lay between one and nine clutches (groups) of eggs per season Females may nest every two to three years Nesting behavior The Kemp's ridley and olive ridley form masses called arribadas (Spanish for "arrival") Arribadas contain thousands of eggbearing females that come ashore at the same time to lay eggs Incubation The incubation time for most species is 45 to 70 days 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 Hatching Hatchlings use a caruncle (temporary egg tooth) to help break open the shell After hatching, the young turtles may take three to seven days to dig their way to the surface. The time immediately before emergence is referred to as a “boil” Hatching 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— towards the brightest spot, the horizon over the ocean Hatchlings When a hatchling reaches the surf, it dives into a wave and rides the undertow out to sea A "swim frenzy" of continuous swimming takes place for about 24 to 48 hours after the hatchling enters the water Hatchlings During the first year, many species of sea turtles are rarely seen. This first year is known as the "lost year" Most researchers believe that they ride prevailing surface currents, situating themselves in floating seaweed where they are camouflaged and where they can find food Longevity Once sea turtles reach sexual maturity, they may have an estimated reproductive life of about 30 years Given that some species reach maturity at 50 years, an 80-year lifespan is feasible Threats to sea turtle survival 1. PREDATION Adult sea turtles have few predators, mostly large sharks Eggs and hatchlings are vulnerable to many predators. More than 90% of hatchlings are predated Threats 2. Fibropapillomas. Green sea turtles are black sea turtles may develop lobed tumorlike growths (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 Threats 3. BEACH DEVELOPMENT/DISTURBANCE Nesting areas are becoming scarce due to beach development and disturbances 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. The noise and activity of people on the beach also may cause females to return to the sea instead of nesting. Threats Artificial lighting on beaches may misrepresent the time of day to turtles attempting to nest. Most turtles are nocturnal nesters, and to a turtle that has not yet come ashore to nest, a brightly lighted beach may signify daylight and inhibit nesting. 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. Threats 4. Pollution Some sea turtles die when they ingest trash. Leatherbacks are especially susceptible to ingesting plastic, mistaking it for jellyfish. Threats 5. Shrimp trawling nets Thousands of sea turtles drown in shrimp nets each year. Sea turtles forage in waters where commercial shrimpers trawl Turtles get stuck in these nets and drown as a result Threats 6. Human predation Some people illegally collect turtle eggs for food and for their alleged aphrodisiac effect. Sea turtles are hunted 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. Conservation & Protection: Legal protection 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. 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 Conservation & Protection: TEDs At a cost of millions of dollars, the National Marine Fisheries Service developed the Turtle Excluder Device (TED). 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. 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. Conservation & Protection: Nest Protection Nests can be protected from predators by placing screens over them. Eggs laid in high traffic beaches can be relocated to safer areas. Those nests left in place on beaches are marked for beachgoers to avoid them Conservation & Protection: Lighting Ordinances Reducing or eliminating beach lighting on developed beaches during hatchling emergence months prevent disorientation of hatchlings Conservation and Protection: Wildlife Refuges Establishing Refuges on important nesting beaches allows nesting sea turtles and hatchlings protection from beach development 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 Conservation & Protection: Wildlife Refuges 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. Local economics is no longer based on turtle harvests, but on tourism Conservation & Protection: Wildlife Refuges The Leatherback Trust has successfully expanded Refuge property in Las Baulas, Costa Rica, in important leatherback turtle rookery. Dr. James Spotila of Drexel University is the President of this organization Conservation & Protection: Education Education local communities and 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. Conservation & Protection: Research Researching sea turtles will allow us to better understand their biology and ecology This will in turn allow ecologists to design better and more effective conservation programs Conservation & Protection: Research Drexel University students are actively involved in many research projects involving sea turtles The Leatherback Trust has been an important force in conserving the leatherback turtle in Costa Rica