009a Marine Reptiles

Phylum Chordata Subphylum Vertebrata 3 Classes: Class Reptilia Class Aves (birds) Class Mammalia

Reptiles, Birds, Mammals Evolved from fish-like vertebrates Moved from the water to the land Developed 2 pairs of limbs for walking – tetrapods Developed lungs to breathe Challenge of land - need to avoid drying out

Lungfish – A Missing Link Class Osteichthyes Subclass Sarcopterygii (lobe-finned) Breathe air through swim bladder Pectoral and pelvic fins → “legs”

What About Amphibians? Lungfish – now only freshwater Amphibians – some tolerate brackish water, none strictly marine Extinct amphibians - ancestors to the reptiles Extinct reptiles – ancestors to the birds

Reptiles Better adapted to life on land than amphibians Skin covered with scales, prevents water loss Eggs – leathery shell, lay on land http://www.ecologyasia.com/images-png/olive-sea-snake_5284.jpg http://www.nps.gov/pais/naturescience/images/greencloseup-285.gif http://cache.daylife.com/imageserve/03ml5d28gEa1Y/610x.jpg

Marine Reptiles Some reinvaded the oceans, but still breathe air: Turtles (Order Chelonia) Snakes (Order Squamata) Iguanas (Order Squamata) Crocodiles (Order Crocodilia) Saltwater crocodile Marine turtle Marine Reptiles (Sea Snakes) Marine Reptiles include sea snakes, saltwater crocodiles, marine iguanas and sea turtles. Sea snakes are a group of true snakes that have completely adapted their life-histories to live in the sea. Sea snake Marine iguana

Marine Reptiles Ectotherms (“cold-blooded”), so mostly in warmer waters, seasonal in temperate waters Cold stunning – Turtles too far north when water temperature suddenly drops (<50°F) Get lethargic, immobile, float to surface, wash up on beach Fatal if not warmed

Marine Turtles (Honu)

History Found in fossil record 200 mya (Triassic) Common in Cretaceous (130 mya) Present day genera originated 60 (Eocene) and 10 mya (Pleistocene) Not a very diverse group Mostly tropical and subtropical

Taxonomy Class Reptilia Order Chelonia- warm to temperate and boreal seas ex. leatherback, ridley's, kemps   Order Chelonia- F. Cheloniidae- green, flatback, hawksbill, loggerhead F. Dermochelidae- leatherback reduced shell, dermal bone scutes compose shell F. Emydidae- diamond back terrapin Hawaii species- green, hawksbill, leatherback, Olive Ridley

Anatomy Dorsal shell = carapace Ventral shell = plastron Head does not retract carapace plastron

Anatomy Female Male

Adaptation to salt water Lacrimal glands

Green turtle Scientific Name: Chelonia mydas Diet: seagrass and algae Size: ~500lbs Conservation Status: threatened Habitat: high energy ocean beaches, convergence zones in the pelagic habitat, benthic feeding grounds in relatively protected waters Range: throughout world in all tropical and subtropical oceans

Kemp’s Ridley Scientific Name: Lepidochelys kempii Diet: mollusks, crustaceans, jellyfish, fish, algae or seaweed, and sea urchins. Size: 100lbs Conservation Status: highly endangered Habitat: shallow water benthic feeder Range: Gulf of Mexico, Texas

Olive Ridley Scientific Name: Lepidochelys olivacea Diet: jellyfish, tunicates, sea urchins, bryozoans, bivalves, snails, shrimp, crabs, rock lobsters, and sipunculid worms Size: >100lbs Conservation Status: highly endangered Habitat: shallow marine waters Range: Indo-Pacific, S. Atlantic NOAA NOAA

Hawksbill Scientific Name: Eretmochelys imbricata Diet: Shellfish Size: 76 - 91 cm (30 - 36 in) Conservation Status: Endangered Habitat: coral reefs, rocky coasts Range: Tropical Atlantic, Pacific and Indian Oceans; Caribbean

Loggerhead Scientific Name: Caretta caretta Diet: Crustaceans Size: 76 - 102 cm (30 - 40 in), 300 lbs Conservation Status: Vulnerable Habitat: coasts, open sea Range: Temperate and tropical areas of the Pacific, Indian and Atlantic Oceans NOAA

Flatback Scientific Name: Natator depressus Diet: sea cucumbers, soft corals, jellyfish Size: < 1 m in length, 200 lbs Conservation Status: vunerable Habitat: near continental shelf, shallow, soft bottom sea beds Range: northern part of Australia

Leatherback Leatherback Largest species (7 ft, 1200 lbs) Family: Dermochelidae: Scientific Name: Dermochelys coriacea Diet: sea jellies and salps Size: 1500 lbs Conservation Status: endangered Habitat: pelagic water Range: tropical seas, oceanic islands, Atlantic, Pacific, & Indian Ocean Leatherback Largest species (7 ft, 1200 lbs) Global, widest distribution Dive deep (up to 4000 ft) “Warm-blooded” (counter-current circulation, fat)

Reproduction 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)

Front flippers dig pit, rear flippers carve out burrow Kemps Ridley nesting 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 Artificial lights- confuse hatchlings Turtle nest Cross section

Incidental Marine Turtle Catches

Marine Debris- plastic bags, soda can plastic rings, fishing line, oil and tar Costal development and habitat degradation- noise, light, beach obstructions- affect nesting habitat

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

Clutch size- about 100 eggs & covers pit with sand Leatherback hatching Kemps Ridley hatchlings 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

Predators

Factors Affecting Green Sea Turtle Population Hawaii- 100-350 nesting females French Frigate Shoals in the Northwest Hawaiian chain Hunters Fisheries Marine Debris Coastal Development and Habitat Degradation Fibropapilloma

Commercial Value Meat Eggs- nearly forbidden in all countries with nesting beaches Soup Jewelry Leather Convention on International Trade in Endangered Species (CITES): turtle commerce prohibited in countries that signed agreement

Protection and Management Law enforcement- in Hawaii, turtles protected under Endangered Species Act Riding or harassing- $100,000 fine + prison time Bringing turtle products into Hawaii- $20,000 + prison time

Protection and Management Increase sea turtle populations: Ranching- eggs or hatchlings from wild populations Farming- originally from wild populations, for breeding stock

Protection and Management Fishing regulations- Shrimp Trawlers - incidental catch by commercial shrimp fish nets: drowned 10,000 turtles each year Drift nets, gill nets Turtle Excluder Device (TED)

Turtle Excluder Device

Sea Snakes Yellow- bellied sea snake Sea Snakes Snakes are cold-blooded (poikilotherms). Consequently, their distributions are restricted to warm waters and sea snakes are only found in the Indo-Pacific region. There is concern that if a sea-level canal were constructed across Panama, they could become introduced to the Caribbean. 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 donÕt 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. Yellow- bellied sea snake

Sea Snakes Diversity: Location: Habitat: Laticodtidae- krates- 5 species (1 is fw in Solomon Islands) Hydrophidae- 54 different species All derived from Colubrid ancestor; colubrids evolved 40 mya; Laticotids evolved from colubrids 30 mya Location: Laticotids- live from east coast India to Japan and come to the tip of Cape York (Australia) Hydrophiids- found from south tip of Africa to India to South East Asian Islands to Japan to north half of Australia Habitat: Primarily tropical; coastal estuaries, coral reefs, open sea; 33-36oC

Sea Snakes 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 Venom: 2-10 times as toxic as that of a cobras

Sea Snakes Adaptations to life in the sea Osmoregulation: skin is impermeable to salts; salts eliminated by sublingual gland Developing a flattened paddle-shaped tail and a laterally compressed body. Reduced metabolic rate and increased tolerance for low oxygen levels Lungs- greatly enlarged; hydrostatic organ Gaseous exchange - lungs and the skin. Developing salt excreting glands under the tongue. 2.Developing a flattened paddle-shaped tail and a laterally compressed body making it an efficient swimmer. 3.Reducing its metabolic rate. Sea snakes are capable of remaining submerged for up to 2 hours by decreasing its metabolic rate and developing an increased tolerance for low oxygen levels. After one breath at the surface, it can dive again. A sea snake also has valve-like flaps over its nostrils to stop water flowing into the lungs. 4.The lungs of sea snakes are greatly enlarged, extending to the base of the tail enabling a large volume of oxygen to be stored in the lungs. 5.Parts of the lung are believed to function as a hydrostatic organ regulating the snake's buoyancy. 6.Gaseous exchange occurs through both the lungs and the skin. Up to 22% of the oxygen is supplied from the sea water through the skin and all excess carbon dioxide is lost into the sea.

Sea Snakes Reproduction: Krates 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 Banded sea krates forming mating group Olive Sea Snake

Saltwater crocodiles Largest living crocodilians: 6-7 m long Eggs laid and incubated on land Tropical and subtropical Saltwater Crocodiles Saltwater crocodiles are the largest of living crocodilians and adults can reach 6-7 m in length. These seagoing animals may travel thousands of miles in the ocean. They are wide-ranging and may move into freshwater areas as well. They havenÕt entirely left land and must return to lay their eggs which are incubated in a terrestrial nest. Their poikilothermic nature means that their distributions are limited to warm areas. Diets include fishes, invertebrates and vertebrates.

Marine Iguanas Endemic to Galapagos islands Herbivorous: graze on seaweeds Salt-glands on nose to eliminate excess salt Recently observed feeding on land for first time They return to land to escape predators. Marine Iguanas These are the only marine lizards and they are endemic to the Galapagos Islands off Ecuador. Marine iguanas have flattened tails that assist them in swimming and they have adapted to an aquatic life. 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 Ni–os may have driven them to forage ashore.

How do marine turtles regulate salt in their body? Inquiry What is a natal beach? What advantage is there in turtle hatchlings leaving in a group rather than individually? Are the consequences for harassing a turtle adequate? How does the fibropapilloma virus effect green sea turtles? What is a TED? How do marine turtles regulate salt in their body?