Marine Iguanas Marine lizard endemic to Galapagos islands These are the only marine lizards. They return to land to escape predators. Marine iguanas have flattened tails that assist them in swimming. Their primary diet are algae that encrust the rocks around the islands.
Iguanas dive to feed on the algae and in the process, their bodies undergo substantial cooling. After diving and feeding bouts, they must warm themselves on land to raise their body temperature. During feeding they accumulate a lot of salt that is excreted via specialized salt-glands on their noses.
Recently, iguanas have been observed feeding on terrestrial vegetation. The stresses of El Nino may have driven them to forage ashore. Sea turtles, saltwater crocodiles, sea snakes, and marine iguanas are the only surviving reptiles that depend on the sea.
Sea Snakes Called a krait Snakes are cold-blooded (poikilotherms). Consequently, their distributions are restricted to warm waters. Sea snakes are only found in the Indo-Pacific region. Sea snakes inhabit estuaries, coral reef areas and the open sea and they are often found in large schooling groups.
Normally, sea snakes are quite docile and dont pose a threat to humans. They have powerful venom which they use to incapacitate fishes or squid. Human fatalities have occurred and these are most common when the snakes wash up on beaches and humans handle the reptiles. They have few natural predators other than sharks, saltwater crocodiles and eagles.
Behavior: Often schooling in aggregations. Not aggressive but human fatalities have occurred. Prey Feed on small fish or squid, which are killed with powerful venom.
Predators (few): Sharks, snapper, grouper, crabs, saltwater crocodiles, raptors. They descend to escape. Osmoregulation Skin is impermeable to salts. Salts eliminated by sublingual gland.
Reproduction: Kraits are oviparous and lay eggs on land Hydrophiids are viviparous and produce young in the water Not much known about breeding However, olive sea snake breed in spring; seasonal courtship displays
Saltwater Crocodiles The animal most likely to eat a human Average-size males reach 17 feet (5 meters) and 1,000 pounds Specimens 23 feet long and weighing 2,200 pounds are not uncommon. Eggs laid and incubated on land Tropical and subtropical They are excellent swimmers and have often been spotted far out at sea.
Classic opportunistic predators. Lurk patiently beneath the surface near the water's edge, waiting for potential prey to stop for a sip of water. Theyll feed on anything they can get their jaws on, including water buffalo, monkeys, wild boar, and even sharks.
Habitat Most commonly found on the coasts of northern Australia, and on the islands of New Guinea and Indonesia. Saltwater crocodiles tolerate salinity and are found mostly in coastal waters or near rivers. They are also found in freshwater near rivers and swamps. Juveniles are raised in freshwater rivers during the wet season between November and March.
Feeding Behavior Saltwater crocodiles have a variety of prey. Juveniles are restricted to small insects, amphibians, reptiles, crustaceans, and small fish. Adults feed on crabs, turtles, snakes, birds, buffalo, shark, wild boar, and monkeys. Saltwater crocodiles hide in the water exposing only their eyes and nose. They lunge at prey, often killing it with a single snap of the jaws, then drag the prey under water where it is more easily consumed.
Reproduction Saltwater crocodiles breed in fresh water during the wet season. Males mark their territory and defend it against other males. Males unable to defend their territory are either killed or forced to find another river system. Females reach sexual maturity between years old followed by males that reach sexual maturity at 16 years. The females lay between eggs on average, but can lay as many as 90 at one time.
She places her eggs and buries them in nests of vegetation and mud which are elevated to avoid loss from flooding during the rainy season. Females protect their nests until the eggs are hatched in 90 days depending on nest temperature. Sex is also determined by nest temperaturemales are produced around 31.6°C (88.9°F). Any deviation from that temperature will result in a female hatchling. Once the female hears the newborn call, she digs up the nest and carries her offspring back to the water in her mouth watching them until they learn to swim.
Marine Turtles The first turtles appeared during the Triassic period, 245 to 209 million years ago. The earliest known sea turtles appear in the fossil record in the Late Jurassic period, 208 to 144 million years ago. Scientists believe that modern sea turtles are derived from marsh- inhabiting ancestors that lived during the Late Triassic period.
Fossil records show that the now-extinct sea turtle Archelon ischyros, which lived 65 to 144 million years ago, was one of the largest turtles that ever lived. It reached a length of 3 to 4 m ( ft.).
Taxonomy Class – Reptilia Order – Testudines This order includes all turtles and tortoises. It is divided into three suborders: 1. Pleurodira (side-necked turtles), 2. Cryptodira (freshwater turtles, snapping turtles, tortoises, soft-shelled turtles, and sea turtles) 3. Amphichelydia (a suborder of turtles that is now extinct).
Families Most scientists recognize two families of sea turtles: 1. Family Cheloniidae includes all sea turtles with scutes (horny plates) covering their shells. 2. Family Dermochelyidae are scuteless turtles with only one modern species; the leatherback turtle. A leatherback turtle is covered with leathery skin. It is the only marine turtle whose backbone is not attached to the inside of its shell.
GENUS, SPECIES Most scientists recognize seven species and one subspecies of sea turtles: 1. Green (Chelonia mydas); Sub species -- black or Eastern Pacific green turtle (Chelonia mydas agassizii) Order: Chelonia Family: Chelonidae Conservation Status: Threatened Habitat: Benthic feeding grounds in relatively protected waters. Range: Throughout the world in all tropical and subtropical oceans. Green sea turtle (Chelonia mydas mydas) Black sea turtle (Chelonia mydas agassizii)
2. Loggerhead (Caretta caretta) Order: Chelonia Family: Chelonidae Diet: Crustaceans Conservation status: Vulnerable Habitat: Coasts, Open seas Range: Temperate and tropical areas of the Pacific, Indian, and Atlantic Oceans. loggerhead sea turtle (Caretta caretta)
3. Kemp's ridley (Lepidochelys kempii) Order: Testudines Family: Cheloniidae Diet: crabs, fish, jellyfish, and mollusks Conservation status: Endangered Habitat: Open ocean and gulf waters with the females only coming ashore to lay eggs in beach sand. Range: Kemp's ridley sea turtles are found in the coastal waters and bays of the Gulf of Mexico and Atlantic Ocean.
4. Olive ridley (Lepidochelys olivacea) Order: Testudines Family: Cheloniidae Diet: algae, lobster, crabs, tunicates, mollusks, shrimp, and fish Conservation Status: Vulnerable Habitat: mainly a pelagic sea turtle, but has been known to inhabit coastal areas, including bays and estuaries. Range: Olive ridleys are globally distributed in the tropical regions of the South Atlantic, Pacific, and Indian Oceans. Olive Ridley Turtle (Lepidochelys olivacea)
6. Flatback (Natator depressus) Order: Chelonia Family: Chelonidae Diet: Sea cucumbers, soft corals, jellyfish Conservation Status: Vulnerable Habitat: Near continental shelf, shallow, soft bottom sea beds. Range: Northern part of Australia
7. Leatherback (Dermochelys coriacea) Order: Chelonia Family Dermochelidae Diet: Sea jellies and salps Conservation Status: Endangered Habitat: Pelagic water Range: Tropical seas, oceanic islands, Atlantic, Pacific, and Indian Ocean
Physiology: Poikilothermic (cold blooded) Skin has scales Speed- 35 mph Breath holding- 2 hrs, when sleeping or resting Maturity yrs for green Cannot retract heads like terrestrial turtles Lacrimal gland- salt secretion (drinks seawater)
Anatomy: Has both internal and external skeleton- provided protection and support for organs Fused ribs Powerful sense of smell No ears, but can perceive low frequency sound and vibrations Male & female- difference in tail size; males tail extends past rear flippers, females is shorter.
Mating- at sea Migration- occurs in late spring; female is accompanied by male Green sea turtles migrate as far as 800 miles from feeding area to nest in Northwestern Hawaiian Islands Egg laying behavior- return to same beach (natal beach)
Usually nest at night Front flippers dig pit, rear flippers carve out burrow Egg tooth- used to chip away at shell Group effort to get out of nest- emerge at night (safer) and head towards brightest light
Clutch size- about 100 eggs & covers pit with sand Egg incubation- 2 months depending upon species Sex determined by temperature- males lower temp, females higher temp Leatherback hatching Kemps Ridley hatchlings
Factors Affecting Turtle Population Marine Debris – Plastic bags, soda can plastic rings, fishing line, oil, and tar. Coastal development and habitat degradation – Noise, light, beach obstructions (affecting nesting habitats).
Fibropapilloma- virus in Green turtles Affects ability to feed, see, move about, or breath May be due to pollutants, blood parasites, or habitat change Kaneohe Bay (1991)- >50% infected
Protection and Management Law enforcement – in Hawaii, turtles protected under the endangered Species Act. Riding or harassing turtles - $100,000 fine + prison time. Bringing turtle products into Hawaii - $20, prison time. Fishing regulations – Shrimp Trawlers – incidental catch by commercial shrimp fish nets: drowned 10,000 turtles each year. Increase sea turtle populations: Ranching – Eggs or hatchlings from wild populations. The End!!