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Sea Turtles Each species of sea turtle is distinctive in appearance and
behavior, all sea turtles have certain characteristics in common the shell
consist of a carapace (upper part) and plastron (lower part), which are joined
together by cartilage called a bridge. in most species with the exception of the
leatherback scutes cover the carapace.
Like all turtles sea turtles have no external ears, they hear best at low
frequencies and their sense of smell is excellent. Though their vision
underwater is good, on land they are nearsighted. Sea turtles spend most of
their time underwater but must come up to breath. During routine activities sea
turtles can dive for about three to five minutes. Sea turtles can sleep for
several hours underwater, but their ability to hold their breath is shortened by
high activity and stress.
This is why sea turtles drown in shrimp nets and other gear in a short time.
Adult sea turtles sleep near rocks or under ledges. Hatchlings and juveniles
sleep on the surface with their front flippers pulled back over the carapace.
Kemp's ridley sea turtle (Lepidochelys kempi) Charming Tortoise of Kemp Ridleys
are the smallest of the sea turtles. The Kemp's ridley is slightly larger than
the olive ridley, measuring 24 - 28 inches in carapace length and weighing 78 -
100 pounds when mature.
An adult is olive green on top and yellowish in color on the bottom, with a
large head and powerful jaws. The carapace is circular to heart shaped.
Hatchlings are dark gray and about an inch and a half long. Kemp's ridleys were
first discovered and described in 1880 by Samuel Garman. But until the 1940's
was not recognized as a species and was often confused with the olive ridley and
the loggerhead.
Confusion continued through the 1950's with many biologist convinced that the
ridleys sea turtle was a sterile hybrid of the green and the loggerhead turtles.
No one could find nesting beaches or an egg-bearing female. In 1963 an old film
was discovered, made in 1947 by Mexican engineer Andres Herrera that showed
nesting ridleys.
The film showed an estimated 40,000 Kemp's ridleys nesting on an isolated
beach now called Rancho Nuevo in Tamaulipas, Mexico, 200 miles south of Texas.
Ninety-five percent of the population comes to the 17 mile strip of beach. The
other five percent nest at the adjacent beach in Veracruz. No other sea turtle
species goes almost entirely to one nesting spot to breed.
The arribada (Spanish for arrival) of Kemp's ridleys in Mexico occurs at
irregular intervals between April and June. Arribadas may occur several times a
season. Male and Females congregate to mate off the coast of the beaches using
wind direction velocity , lunar cycles and water temperature to gather is a
theory. Once mated females wait for ideal conditions to come ashore. Conditions
generally are high wind and heavy surf. The high wind cools stressed females and
hides traces of the nest from predators.
Mass nesting is thought to be a predator swamping where females and
hatchlings will die but many more will survive. Herrera's film is now being used
as a base line to measure the rapid decline of Kemp's ridleys since 1947.
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