As oldest surviving reptiles,
turtles ere built for survival
WASHINGTON - Their an
cestors roamed the earth some 275
million years ago, even before the
Appalachian Mountains were
formed. The first recognizable
member of the species appears in
the fossil record about 185 million
years ago, many eons before the
peak of the dinosaurs. And today,
long after the dinosaurs’ demise,
the turtle remains, its dome still
perched on its back.
“Turtles seem to have hit on a
good, conservative thing,” says
Dr. Archie Carr, a world authority
on them. “Turtles clung to their
basic structural design, while
many other animals experimented
their way into extinction.”
Many unique features help the
turtle survive in an increasingly
hostile world, writes freshwater
turtle specialist Christopher P.
White.
Very Flexible Neck
The turtle’s protective shell
actually consists of two parts the
top half, called the carapace, and
the lower half, the plastron. Eight
vertebrae in this reptile’s neck,
compared with the seven of most
mammals, allow most turtles to
fold their necks and retract into
their shells. Most turtles also can
retract all four limbs as well as
their head between the two shells.
In addition to breathing through
a set of lungs, freshwater turtles
can use their mouth cavity in gill
like fashion. Water is drawn
through the nostrils, oxygen ab
sorbed in the mouth, and the water
expelled. A few turtles can even
absorb small amounts of oxygen
through their skin while sub
merged in mud.
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Aquatic turtles have little in
common with the pokey tortoise
that almost lost the race to the
hare. They’re extremely fast. The
smooth softshell turtle, for
example, can outswim the speedy
brook trout. Webbing between toes
increases swimming speed while
allowing some species to walk
underwater to browse.
The world’s 180 kinds of fresh
water turtles include animals
patterned with dots, splashes, and
hieroglyphs. The spotted turtle, for
instance, is sprinkled with dozens
of yellow polka dots. The markings
on the juvenile map turtle
resemble contours on an ancient
chart.
Freshwater turtles vary in size
from the stinkpot, a three-inch
long variety that exudes a musky
fluid when disturbed, to the
alligator snapper, a giant native of
the south-central United States
that can weigh up to 250 pounds.
Snaps Off Fingers
The bite of the alligator snapper
is legendary. “Late one night 16
years ago,” related a veteran
Florida turtle hunter, “my son and
I pulled an old 75-pound alligator
snapper out of a swamp. Like a fool
I put the snapper right behind me
in the boat. After a time we got
stuck in some reeds, so I reached
back for a paddle and slam!
something hit my hand so fast I
didn’t know what had happened.
Then all of a sudden there was
blood everywhere, and my son was
shouting, ‘Dad, two of your fingers
just dropped into the bottom of the
boat!”’
Those who dare to peer into an
alligator snapper’s mouth would
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A Suwannee cooter, one of the world's 180 species of freshwater turtles, cruises the
waters of Florida's Rainbow Run. Webbing between toes speeds turtles through water,
and a gill-like mouth cavity allows them to breathe. Contemporaries of dinosaurs, turtles
are the world's oldest surviving reptiles.
see a rose-colored wormlike ap
pendage projecting from its
tongue, used to lure minnows.
Dissected stomachs of alligator
snappers have turned up baby
alligators, raccoons, snakes,
acorns, shoes, and other turtles.
The increasingly rare alligator
snapper is still legally hunted in
many states. A few other turtle
species, such as New England’s
Plymouth red-bellied turtle, are in
more serious trouble. Considered
endangered since 1980, a few
hundred red-bellies survive in
glacial ponds with the help of
conservationists.
One threat to some freshwater
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turtles’ survival is a slow rate of
reproduction. Mating can be
elaborate. Each species has a
courtship ritual of its own. Com
mon snapping turtles, for example,
face each other and sweep their
heads from side to side in opposite
directions. After several minutes,
the two turtles return their heads
to dead center and stare at each
other for a while before mating.
The male red-eared slider tickles
the female’s neck as he swims
backward and she forward. The
two eventually sink to the pond
bottom, where they mate.
Egg laying can be nearly as
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ritualistic. Many females dig a
chamber near water’s edge, lay
their eggs, and cover the nest. At
least three varieties, however,
practice triple clutching. They lay
most of their eggs in a main nest
and then add two smaller pockets
for one or two eggs each. Some
scientists believe the pockets are
decoys, designed to distract
predators from the main clutch,
but Archie Carr has doubts.
“Two or three eggs in little side
pockets aren’t going to fool a
hungry raccoon they probably
act more like a beacon,” he says.
“It’s still a mystery, and I’ve been
losing sleep over it for 30 years.”
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