69 10.3 Marine Reptiles
Marine Reptiles
Marine reptiles are cold blooded (ectothermic), meaning that their internal temperature is regulated by their surroundings and is not constant. They have scales that cover their bodies, they reproduce out of the water, and they evolved from amphibians. Today’s marine reptiles include turtles, sea snakes, iguanas, and marine crocodiles.
- 5 widely distributed tropical and subtropical species:
- Green, Hawksbill, Ridley, Leatherback and Loggerback
- All have large limbs and non-retractable heads
- All are excellent swimmers: the front limbs are flattened to act as oars, while the hind limbs work as rudders
- All grow to considerable size: the Atlantic Leatherback is the largest, growing to more than 1500 lbs and 11.5 ft long
- All are under threat of extinction
- The Green turtle is known for its long migrations, often of more than a thousand miles, between its feeding grounds and breeding areas
- Some use smell and vision, wave patterns, the angle of the sun and even celestial navigation to find a beach site close to where they were hatched
- if they survived there, then their offspring is more likely to survive
Sea snakes:
- There are more than 50 species, which represent the most recently evolved group of marine reptiles
- They’re found primarily in the warm oceans of the Indo-Pacific, but some can be found in the Atlantic (as seen in my photo)
- They grow to lengths of 4 to 10 feet
- Their bodies are flattened for swimming
- They breathe air, but have valves on their noses and can dive for crustaceans or shellfish
- They’re truly marine except for one species that lays eggs on land – most give live birth at sea
- They also feed on small fish
- by catching and holding them in their jaws with their small teeth until their venom seeps into the wounds and kills the prey
- Their venom is among the most active of all known biological poisons
- the physiological effects are similar to those of cobra venom, only several times more toxic
- Fortunately for humans, they lack fangs to inject the venom and they are not terribly aggressive
- However, several people a year die from the bites of sea snakes, mostly fishermen who accidentally get bitten while removing them from their nets
Marine Iguanas:
- Found in the Galapagos Islands
- They’re large, heavy and sluggish on land, but much more graceful in the sea
- They eat encrusting algae that they scrape from rocks with their spade-like teeth
Marine Crocodiles:
- These are occasional seafarers
- And are found mostly in the Indo-Pacific area from India to Australia
- They may grow to 30 ft in length
- They may be endangered because of predation by humans
Dr. Cristina Cardona