MARINE REPTILES ZARA KOERBER; SAMUEL CRIDLAND PERIOD 2

MARINE REPTILES FIRST STARTED APPEARING ON EARTH IN THE PERMIAN PERIOD (298.9 TO MILLION YEARS AGO) DURING THE PALEOZOIC ERA (541 TO MILLION YEARS AGO). THEY STARTED ADAPTING TO THE LIFE OF THE SEAS IN THE MESOZOIC ERA (252 TO 66 MILLION YEARS AGO). COMMON ANIMALS THEN WERE THE ICHTHYOSAURS AND PLESIOSAURS. AFTER A WHILE MORE ANIMALS APPEARED SUCH AS OUR COMMON DAY SEA TURTLES. AT THE END OF THE CRETACEOUS PERIOD (145 ± 4 TO 66 MILLION YEARS AGO) THERE WAS A MASS EXTINCTION WHICH LEAD TO CREATING OUR COMMON DAY MARINE REPTILES. Those marine reptiles were the sea turtles, sea snakes, marine iguana, and the saltwater crocodiles (although not considered to be true marine reptiles). These marine reptiles belong to the phylum Chordata The Chordates are animals with a notochord (which is a hollow dorsal nerve cord), pharyngeal slits, endostyle, and a tail for most of their life. There are over 65,000 living species of chordates in our world today. They range from the class of Ascidiacea all the way to Synapsida. We will be focusing on the Sauropsida which is the reptiles. But even in the reptiles class there is over 10,000 species (including birds). So we will be focusing even more on those reptiles that live in the sea. These marine reptiles are secondarily adapted to living in the sea or for at least semi-aquatic life in the ocean.

Ichthyosaur (Greek for fish lizard) Plesiosauria (Greek for “near to” and Sauira)

HABITAT, REPRODUCTION, FEEDING, PREDATOR & PREY FT. SEA TURTLES Sea turtles are in the superfamily chelonioidea and the order testudines.  There are seven species of sea turtles: the green, loggerhead, kemp’s ridley, olive ridley, hawksbill, flatback, and leather back.  sea turtles can be found in mostly all regions except polar regions. They can be found mostly near coral reefs and some turtles even travel between oceans.  During mating season a female and a male will mate then the female will come ashore, almost always at nighttime, and will begin digging. Once the hole is about 20 inches deep she will start filling the nest with her eggs. Some turtle species can lay up to 350 eggs. They will hatch in days. And the sex of the turtle depends on the temperature of the sand while the egg is incubating (cooler temp tends to make more males).

HABITAT, REPRODUCTION, FEEDING, PREDATOR & PREY FT. SEA TURTLES  Six of the seven species remain omnivorous for their entire life span. They tend to feast on decapods, seagrasses, seaweed, sponges, mollusks, cnidarians, echinoderms, worms, and fish. Leatherback turtles exclusively feed on jellyfish and hawksbills eat lots of sponges which mostly come from the Caribbean.  As for the green sea turtles, they start out as omnivores but as they mature they become herbivores.  Predators can feed on turtles at all stages of their life. When they are little eggs raccoons and foxes can dig into the nests. When they hatch they can be eaten by seabirds and the former animals. Once they reach the water seabirds can still gobble them up and so can large fish and maybe even other turtles. Once the tiny little sea turtles mature they actually have few predators. Sharks and crocodiles tend to be the largest threat aside from humans.

HABITAT, REPRODUCTION, FEEDING, PREDATOR & PREY FT. HYDROPHIINAE (SEA SNAKES) Habitat  Hydrophiinae which are sea snakes which include coral reef snakes are related to the venomous elapid snakes. But these sea snakes are found in the tropical waters of the Indian Ocean all the way to the Pacific Ocean. A few are found in the Oceania. These snakes prefer shallow waters near land like coral reefs. They go on to land every once in a while, one time they were found 99miles from the ocean. Sea snakes inhabit mangroves and islands far from the main shore. Reproduction  The Hydrophaiinae are all ovoviviparous (except for one genus) which is where the young are born alive in the water where they live their entire lives. When born they can be quite large, sometimes almost as long as the mother.  The one that is an exception is Laticauda which is oviparous.  3o

Habitat, Reproduction, Feeding, Predator & Prey ft. Hydrophiinae (Sea Snakes) Hydrophiinae don’t have to much of a complicated diet. In the ocean they occasionally eat on small fish and young octopods. The predators of Sea Snakes include birds, sharks, large fish, eels, and crocodiles.

HABITAT, REPRODUCTION, FEEDING, PREDATOR & PREY FT. MARINE IGUANA The Marine Iguana is only found on the Galapagos Islands. Because it has adapted to survive in a marine environment it can dive 9ft underwater. It prefers the warm water. The reproduction season for the iguana is during the cold dry season. Females mature in 3-5 years after being born and the males 6-8 years. The females select the males based on size, them the female will lay one to six eggs.

HABITAT, REPRODUCTION, FEEDING, PREDATOR & PREY FT. MARINE IGUANA Marine Iguanas are very picky when it comes to their diet. They eat 4-5 species of algae. They prefer to eat red algae but it is harder to get to. Statistics show that only 5% of iguanas are willing to dive off shore into the water to reach the algae, most of them are males. That’s why foraging becomes necessary. On the islands there isn’t many predators to the iguanas but the ones known are the hawks, owls, snakes, crabs, rats, dogs, and cats.

HABITAT, REPRODUCTION, FEEDING, PREDATOR & PREY FT. SALTWATER CROCODILE  The saltwater crocodile isn’t truly a marine reptile but it does still reside in the oceans and mangrove habitats. Three of the species of crocodile are found in India, the other two are found more regionally.  The reproduction season is in the wet season. In Australia the season if from September to October. Females lay the eggs in nests that are often exposed.

HABITAT, REPRODUCTION, FEEDING, PREDATOR & PREY FT. SALTWATER CROCODILE Crocodiles aren’t picky with their diet just like the most reptiles. They have adapted to survive on a limited amount of food for an extended period of time. The prey they eat would be fish of all sizes, crustaceans, molluscs, birds, mammals, etc. It’s the hatchlings that mostly have predators but when they are fully grown the biggest fear to them is the humans. Although there have been stories of snakes eating crocodiles and sharks, tigers, lions, and jaguars. Hippopotamus are herbivores and won’t eat the crocodiles but might accidently step on them, crushing them.

ADAPTATIONS OF MARINE REPTILES  Reptiles who were forced to live near/in the ocean had to adapt. Their body developed ectotherm (controlling body temperature), anaerobic metabolism, tolerance of acid-base disturbance, ventilation with apneic periods, and a circulation system with intra-ventricular shunting.  The skin plays an important role as well by avoiding salt entry to keep the chemical composition in the body at normal levels.  For marine reptiles the apneic periods are longer than terrestrials so they can stay underwater for longer periods of time with no effort.

HUMAN IMPACTS ON MARINE REPTILES  Artificial lighting can be very dangerous to sea turtles especially those who just hatched. When hatched the sea turtles are designed to go towards the moon light reflecting off the water. With the increase of lighting on the shore line hatchlings go the wrong way into death.  The human impacts on marine iguanas would be the increase of non-native species arriving on the Galapagos islands. The iguanas have no defense to these new animals.  For the crocodiles humans kill them and skin them for their skins.

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