In the Region :: Marine
Mammals :: Marine
Turtles :: Strandings
:: Beach Response
 Marine
Turtles
As reptiles, marine turtles:
· lay eggs
· breathe air
· have scales
· have backbones (vertebrae)
· are cold-blooded (cannot regulate their internal body
temperature)
With the exception of a few sea snakes, marine turtles are the
only reptiles that spend their lives in the ocean. Their bodies
are well adapted to ocean life, streamlined with powerful flippers
rather than feet. They are generally solitary animals, interacting
with each only during mating.
As cold-blooded animals, unlike mammals, they take on the temperature
of the water around them. Therefore, they spend most of their time
in warm water. Scientists believe that, as juveniles, the turtles
that we see in the Eastern US follow the warm Gulf Stream waters
of the Atlantic Ocean from the Caribbean to feeding grounds north
of Cape Cod.
World-wide, there are 7 species of sea turtles:
· Loggerhead
· Kemp's Ridley
· Leatherback
· Green
· Hawksbill
· Flatback
· Olive Ridley
The species are identified by the shape of the head and the pattern
of the scutes on the carapace.
The first five are often seen in Atlantic waters around Cape Cod.
The other species, Flatback and Olive Ridley, live in the Pacific
Ocean. All except the Flatback are threatened or endangered species.
With the exception of Leatherback turtles, marine turtles are cold-blooded
animals. This means they are incapable of regulating their internal
body temperatures, unlike mammals, and are believed to spend the
majority of their time in warm waters.
Photo credit: thanks to Don Lewis, Wellfleet Bay Wildlife Sanctuary
Marine turtle adaptations for life in the sea include a streamlined
body, long wing-like flippers for swimming, and color patterns on
the scales (scutes) covering its shell that help camouflage it in
deeper waters. Their lungs are adapted for long, deep dives and
an almost complete exchange of air when they surface to breathe.
Like land turtles and freshwater turtles, sea turtles, except leatherbacks,
have hard shells made of bony plates. The top of a turtle's shell
is called the carapace. The bottom shell, called the plastron, is
much smaller than the carapace. Unlike land turtles, sea turtles
can not pull their heads and long flippers inside their shells for
protection.
A sea turtle's life span is similar to humans. They reach sexual
maturity in late teens or twenties. Sea turtles return to the area
where they were born. Female sea turtles lumber up the nesting beaches
at night, dig a deep hole in the sand with their rear flippers,
lay their eggs (usually more than 100), and then fill in the hole
and camouflage the nest before hauling themselves back into the
sea.
 The
eggs in a sea turtle's nest all hatch at once, and the baby turtles
dig frantically upward through the sand. Hatchling turtles then
head straight for the sea. Birds, crabs and other predators on the
beach will grab many of them before the babies reach the ocean's
edge. Only about one in 1,000 hatchlings survive to adulthood.
Photo credit: thanks to Don Lewis, Wellfleet Bay Wildlife Sanctuary
One of the mysteries about sea turtles is how the hatchlings, only
minutes out of their shells, know to head toward the ocean. In fact,
many scientists believe that the lights from coastal towns and shore
developments confuse hatchlings, causing them to run inland instead
of toward the ocean.
Even though marine turtles lay their eggs on the shores of the
Caribbean and southern US states, they are seen frequently in the
colder North Atlantic regions, including the waters around Cape
Cod. It is widely believed that, as juveniles, they follow warm
water currents to the rich feeding grounds of Stellwagen Banks just
north of Cape Cod.
When the water and air turn cold in the fall, any turtles that don't
get back into warm water currents become "cold stunned."
In this condition, their internal organs slow their functions and,
if not reversed, the turtles die. Cold-stunned Kemp's Ridley, Loggerhead,
Hawksbill and Green turtles (and an occasional hybrid) are found
by the dozens on Cape Cod beaches in the late fall.
Loggerheads are carnivores, eating fish, squid, shrimp,
clams, crabs and mussels. Their stomachs are adapted to digesting
the hard shells of these shellfish.
Adult Green turtles are vegetarians, feeding on algae and sea grasses.
They got their name from the color of their fat. Many people who
live in tropical countries find them quite tasty, so Green turtles
are widely hunted for turtle soup.
The Leatherback sea turtle is very unusual. Rather than a hard
shell, it has bony plates embedded in its skin that form long ridges
down its back. Leatherbacks grow to be five to seven feet long and
can weigh more than 1,000 pounds!
Unlike most marine turtles, Leatherbacks can regulate its body
temperature and can live in colder waters. Adult Leatherbacks migrate
between warm Caribbean waters and the cold Arctic Sea in search
of their main food: jellyfish.
The Hawksbill sea turtle takes its name from its beak-like mouth.
Hawksbills live in tropical waters near coral reefs, where they
scrape and pry sponges, urchins, and algae from the hard coral skeletons.
People use the beautiful "tortoise shell" shells (scutes)
to make jewelry and other decorations. To help protect these animals,
the U S government has made it illegal to bring real tortoise shell
trinkets into the country.
Humans are contributing to the endangered status in other ways.
In many parts of the world, people catch and eat the turtles or
dig up the eggs for food. Some get caught accidentally in fishing
nets and drown. And sometimes, the species of sea turtles that eat
jellyfish may eat plastic bags they find floating in the ocean -
an often fatal mistake.
There is still much that is unknown about marine turtle life cycles
and migration patterns. While juveniles are frequently seen in near-shore
waters, as adults they "disappear." Scientists refer to
the "lost years," the period when juveniles mature and
then the females re-appear to lay their eggs on their home beaches.
This presents opportunities for the NMLC project to include a research
component - tagging and tracking released turtles.
DISTINGUISHING SEA TURTLES AND LAND TURTLES
Marine turtles are adapted to life at sea with long, wing-like
flippers. Front flippers are used for stroking and hind flippers
for steering. Toes have evolved as the edge of the flippers,
with one or two nails visible depending upon the species. |
Land turtles have legs. Their swimming action is more like
a "dog paddle." Their toe nails are clearly distinguishable. |
Marine turtles spend their entire lives in the ocean. Only
the females come ashore, and then just long enough to lay
their eggs. |
Land turtles spend much of their lives out of the water.
|
Marine turtles have lost their ability to right themselves
if they get turned onto their back. |
Land turtles can right themselves if they get turned onto
their back. |
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