Sea Turtles in the Classroom: A Model for Science Education

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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

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Drexel University

• Study turtles in the city, you ask?!?

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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

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Drexel University

• Professors at Drexels Center for Biodiversity
  and Conservation have decades of years of
  experience and hundreds of publications in the
  field of turtle biology, ecology, and
  conservation!

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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

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Current Research

• Drexel students, as well as students from other
  Universities and Earthwatch volunteers, carry out
  an extensive research program on Costa Ricas
  population of Leatherback sea turtles
• These efforts include movement studies, nesting
  studies, and hatchling studies

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Current Research

• Research on turtles in not confined to marine
  turtles, however

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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

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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

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Current Research

• Amanda Curtin has devoted her doctoral research
  to a osteological growth study of the desert
  tortoise

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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

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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

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Introduction

• Of all animals, the humble turtle seems to
  capture the imagination and wonder of children of
  all ages the most

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Introduction

• Turtles have found themselves a part of popular
  culture
• Who can forget Yertle and the Art of Turtle
  Stacking??

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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

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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

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Introduction

• Whether revered as a cultural and spiritual icon
  or just thought to be cool...
• Just about everybody likes turtles!!!

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Introduction

• This interest in the organism itself can be used
  as an advantage to todays 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

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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.

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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).

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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".

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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

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Sea Turtles of the World
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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

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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.

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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

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• 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

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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.

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• 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

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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

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• 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

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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

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• 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

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Kemps 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.

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• 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

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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.

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• 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

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Distribution and Habitat

• Sea turtles live inhabit all of the worlds
  oceans
• Adults of most species are found in shallow,
  coastal waters, bays, lagoons, and estuaries.
• Some also venture into the open sea.

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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.

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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

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Migration

• Loggerheads leave foraging areas and travel on
  breeding migrations that range from a few to
  thousands of miles

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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

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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.

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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

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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.

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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.

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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.

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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

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Head and jaw

• The jaw structure of many species indicates their
  diet

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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

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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

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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

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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

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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

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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

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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

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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

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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

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Nesting behavior

• Females usually lay between one and nine clutches
  (groups) of eggs per season
• Females may nest every two to three years

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Nesting behavior

• 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

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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

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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

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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
  groupstowards the brightest spot, the horizon
  over the ocean

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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

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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

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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

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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

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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

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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.

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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.

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Threats

• 4. Pollution
• Some sea turtles die when they ingest trash.
  Leatherbacks are especially susceptible to
  ingesting plastic, mistaking it for jellyfish.

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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

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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.

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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

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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.

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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

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Conservation Protection Lighting Ordinances

• Reducing or eliminating beach lighting on
  developed beaches during hatchling emergence
  months prevent disorientation of hatchlings

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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

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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

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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

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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.

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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

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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