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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