There are four families of marine reptiles: saltwater crocodiles,
sea snakes, marine iguanas and sea turtles.
Sea snakes. "Scientific classification: Sea snakes are usually
classified in two subfamilies, the Hydrophiinae and the Laticaudinae,
both in the family Elapidae. Some taxonomists classify them instead
in two families, the Hydrophiidae and Laticaudidae, separate from
the family Elapidae. Stokes's sea snake is classified as Astrotia
stokesii. The yellow-bellied sea snake is classified as Pelamus
Sea Snake, common name for certain marine members of a family of
venomous snakes. Sea snakes inhabit the tropical waters from the
Indian to the Pacific oceans; they are particularly abundant in
the Persian Gulf and the Bay of Bengal. Most sea snakes are not
large, ranging from about 0.5 to 1 m (1.6 to 3.3 ft) in length,
although Stokes's sea snake can reach nearly 2 m (6.6 ft). One group
of sea snakes, sometimes called the true sea snakes, give birth
to live young and lack the enlarged ventral scales typical of most
terrestrial snakes. The other group, sometimes referred to as seakraits,
lay eggs; because they must leave the water to deposit their eggs,
they retain straplike ventral scales, although these may be smaller
than those of terrestrial snakes. The paddlelike tail of sea snakes
is wide and compressed and makes an effective swimming organ. Unlike
eels, sea snakes have no gills and must rise to the surface of the
water for air, but they can remain underwater for several hours,
obtaining dissolved oxygen from water that they swallow and eject.
Many species feed on elongate fishes, such as eels, which they paralyze
with their venom. They are generally not aggressive and usually
will not bite humans unless handled roughly or forcibly restrained.
The yellow-bellied sea snake, one of the most common sea snakes,
ranges along the Pacific coast from southern California to northern
South America. It is less than 1 m (3.28 ft) long and is black or
dark brown with a bright yellow belly." (The reptile refrence: http://www.iversonsoftware.com/business/reptile.html)
Crocodiles: "Crocodilians first appeared about 200 million years
ago and are believed to be remnants of the great age of reptiles.
Their ancestors originally lived on land and were lightly built,
but they soon diversified into water-dwelling, or aquatic, and amphibious
forms. Except for the alligators, crocodilians live in tropical
and subtropical areas of the world. Modern crocodilians are amphibious,
spending much of their time in water, where they swim with rhythmic
strokes of the tail. The tail is sometimes used to capture prey,
sweeping it from shallow to deeper water, where it can be devoured
Crocodilians are well-adapted as predators, with few natural enemies.
Bony plates, called osteoderms, form a kind of armor in their thick
skin. Their teeth, about 30 to 40 in each jaw, are set into sockets
in the jawbones and interlock when the mouth is closed. In crocodiles,
the fourth tooth on each side of the lower jaw protrudes when the
mouth is closed; in alligators, these teeth are not visible. The
jaws of crocodilians are powerful enough in closing to crush the
bones of small animals, but so weak in opening that they can be
held together by hand. As the crocodilian floats almost completely
submerged, its protruding nostrils and eyes and a portion of its
back are the only parts visible as it stalks its prey. Crocodilians
are the most vocal reptiles, producing sounds from quiet hisses
to fearsome roars and bellows, usually during the mating season.
On land, crocodilians move quickly in a belly crawl but can also
gallop and walk mammal-like on all four legs.
Crocodiles are physiologically the most advanced reptiles; their
internal anatomy resembles that of birds. They have a four-chambered
heart and well-developed senses. Cold-blooded like all reptiles—their
body temperature depends on the environment—crocodilians bury themselves
in mud to estivate or hibernate. In warm regions they are dormant
during droughts; in colder regions, during winter. Crocodilians
are egg-laying, or oviparous, reptiles, reaching reproductive maturity
at about the age of ten. The eggs, 20 to 90 in number and about
the size of goose eggs, are buried in sand, mud, or vegetable debris,
where they are left to hatch by the heat of the sun or of vegetable
decomposition. Females of some species remain in the area to protect
the nest and care for the newly hatched young, although many of
the eggs and young are lost to predators. The parental behavior
of crocodilians is unique among reptiles and points to their affinity
with birds." (http://www.iversonsoftware.com/business/reptile.html)
Marine Iguana sp[ecies: "Amblyrhynchus cristatusTo be enthusiastic
about a Robinson Crusoe life-style is one thing. To actually live
more than half a year on a desert island in the middle of the Pacific
Ocean is another, especially if you cannot take along fresh fruits
(because of the possibility of introducing exotic plants and insects)
and there is no electricity, not to mention refrigeration. One also
learns how to get by with very little fresh water when one has to
carry every single quart and receives supplies only once a month.
But when my two Ecuadorian co-workers, Victor Carrillo and William
Revelo, and I landed with our gear on the rocky coast of Santa Fe,
in the Galapagos archipelago, we didn't think about the hardships
To cope with the high salt content of their diets, marine iguanas
have the most efficient salt-excreting glands of all reptiles. The
glands are located just above the nostrils. By sneezing frequently,
the lizards expel the salt in small white geysers, which often give
these black lizards a whitewashed look. After eating, a marine iguana
must reset its body temperature and heart rate (from 30 to 100 beats
per minute), because the digestive system works best at a constant,
relatively high temperature. By flattening their dark bodies against
the warm lava rocks, the lizards expose as much skin surface as
possible to the sun and the rock surface. The flow of heat from
the rocks is controlled by vessels in the marine iguanas' chest,
which close and open to regulate body temperature. To prevent overheating,
the lizards elevate their torsos and face the sun, thereby diminishing
the amount of body area exposed and allowing the cooling coastal
breezes to convect heat away. Unable to sweat, most marine iguanas
pant when the temperature approaches 104 degrees. Not so the hatchlings;
they sometimes enter the intertidal flats with body temperatures
of 108 degrees and, in general, have higher body temperatures than
all the other marine iguanas. This allows them to digest their food
in half the time adults require and supplies the energy needed for
fast growth." (Maritn
sea turtle species: Caretta caretta: Loggerhead Sea Turtle
According to the Website - Turtle Trax, a 1990 study showed that
the S.E. of the US recorded 50-70,000 nests which they estimate
is 30-40% of the world population of loggerehads.
Decline in Australian rookeries (Limpus and Reimer 1994)
Florida populations stable.
South African doubled since early 1960s (Hughes 1989)(Euro Turtle:
Chelonia agassizi: Black Sea Turtle
Inhabits coastal waters of the eastern tropical Pacific ocean.
Not commonly observed in the opean ocean. :
Chelonia mydas: Green Sea Turtle; (2,000) waters.
Rarely nest in waters below 25 degrees C.
Near continental coasts and around islands.
Rare in temperate waters.
Along with hawksbill, the most tropical of turtles.
Some estimated population figures shown above.
Many populations on the decline, mainly in Australasian region.
Here, 100,000 green turtles per annum harvested for meat.
Near total egg harvesting in Indonesia and Malaysia. (Sarawak Turtle
Strong conservation in Sabah, Hawaii and Florida have seen some
recovery" (Euro Turtle: http://www.exeter.ac.uk/telematics/EuroTurtle/dleath.htm
Eretmochelys imbricata: Hawksbill Sea Turtle;
Wide spread nesting patterns with few very large nesting places.
Nesting confined to 25 degrees N and 35.5 degrees S.
Population: According to the Website Turtle Trax, 38 out of 65 population
areas are on the decline.
Population difficult to assess but under pressure from commercialization
for its shell.
According to Agardy (BBC Wildlife) 1992 approx: (Limpus 1995)(Euro
Lepidochelys kempii: Kemp's Ridley Sea Turtle; are still being
added up. Since each female is thought to lay an average of 2.3
clutches, it is likely that about 1671 turtles laid these clutches.
Only a portion of adult Kemp's ridley females nest every year."
(Euro Turtle: http://www.exeter.ac.uk/telematics/EuroTurtle/dleath.htm).
Lepidochelys olivacea: Olive Ridley Sea Turtle; " (Euro Turtle:
Dermochelys coriacea: Leatherback Sea Turtle; "Range: Widely distributed
and can be found in colder waters due to ability to thermo-regulate.
Highly pelagic species
Population: In 1980, the population was estimated (Ripple) at between
70,000 and 115,000 but since then it has declined at an alarming
rate to its present estimate (Spotila) of about 34,500. Most important
rookeries are northern coast of South America, especially French
Guiana. Also good populations in Mexico. Serious declines are being
observed in Malaysian nesting sites (Terengganu - Limpus/Bjorndal).
Some recent articles and papers are: Hell for Leatheries - an article
by Tom Langton in the BBC Wildlife Magazine (March 1999, Vol.17,
Worldwide Population Decline of Dermochelys coriacea: Are Leatherback
Turtles Going Extinct? (1996?)"(Euro Turtle: http://www.exeter.ac.uk/telematics/EuroTurtle/dleath.htm).