Conservation and Ecology of Marine Reptiles MARE 490 Dr. Turner Summer 2011

Class Reptilia Order Chelonia – marine turtles Order Squamata – marine snakes and iguanas Order Crocodilia – saltwater crocodile

Order Squamata Snakes evolved from lizards ≈ 135 mya There are approximately 70 species of sea snakes living in our modern oceans They account for 86% of marine reptile species alive today

Order Squamata Suborder: Serpentes – snakes Infraorder: Scolecophidia – blind and thread snakes; 3 families, 12 genera Infraorder: Alethinophidia – all other snakes; 15 families, 9 subfamilies, 316 genera

Suborder Serpentes Infraorder: Alethinophidia Family Acrochordidae - file snakes – 3 sp. Family Elapidae - cobras, coral snakes, mambas, sea snakes Subfamily Homalopsinae - mangrove snakes – 10 sp. Subfamily Hydrophiinae - ‘true’ sea snakes – 54 sp. Subfamily Laticaudinae - sea kraits – 5 sp. Family Colubridae Subfamily Natricinae - salt marsh snakes – 3 sp.

Order Squamata Family Elapidae - characterized by a hollow fixed front fang and neurotoxic venoms Elapids have been divided into between 0, 2, or 6 subfamilies

Family Elapidae New Taxonomy – No subfamilies Old Taxonomy - Several subfamilies: Subfamily Elapinae - African elapids Subfamily Hydrophiinae - sea snakes Subfamily Micrurinae - coral snakes Subfamily Acanthophiinae - Australian elapids Subfamily Laticaudinae - sea kraits Or Subfamily Hydrophiinae – Sea snakes & kraits Subfamily Elapinae – Cobras, coral, & terrestrial kraits

Classically 5 major groups of “sea snakes” Hydrophiids - ‘true’ sea snakes – 54 species Laticaudids - sea kraits – 5 species Acrochordids - file snakes – 3 species Homalopsids - mangrove snakes – 9 species Natricids - salt marsh snakes – 3 species

Hydrophiids - ‘true’ sea snakes The largest group of sea snakes Evolved from Australian terrestrial elapids that returned to the marine environment around 30 million years ago Have the same toxic venom and envenomation apparatus (they are proteroglyphs meaning they have fixed front fangs) as their terrestrial ancestors

Hydrophiids - ‘true’ sea snakes Have exploited the viviparity that exists in some of their terrestrial ancestors, and have thus freed themselves entirely from the need to return to land to breed 54 species of hydrophiid sea snakes

Laticaudids - sea kraits Comprise five species, four of which are marine Are strongly banded and commonly seen in large numbers on beaches in south east Asia and some Pacific Islands

Laticaudids - sea kraits Sea kraits have also evolved from terrestrial elapids and are proteroglyphs and have highly toxic venom. However they are very placid and unlikely to bite unless provoked. Sea kraits are the only group of sea snakes that are oviparous (egg laying) and must return to land to breed.

Acrochordids - file snakes Comprise three species One species is fully marine while the others live in estuaries and freshwater habitats Are not venomous & give birth to live young

Homalopsids - mangrove snakes Confined almost entirely to estuarine environments Are nine species found primarily in tropical Asian waters and northern Australian waters Only three species are fully marine Homalopsids are venomous but they are rear-fanged

Natricids - salt marsh snakes Confined to salt marsh environments Three species of marine natricids Confined to temperate & subtropical N. America Are not venomous Early stages of evolving marine adaptations

Order Squamata Subfamily Hydrophiinae – Sea snakes & sea kraits Subfamily Elapinae – Cobras, coral snakes, terrestrial kraits

Subfamily Hydrophiinae Subfamily Hydrophiinae – Sea snakes & sea kraits Sea kraits - amphibious (living on land and water), oviparous (returning to land to lay their eggs, have specialized ventral scales for crawling on land Sea Krait

Subfamily Hydrophiinae Sea snakes – fully aquatic (never leaving the water ovoviviparous (bear their young in the water) lack specialized ventral scales Sea Snake

Sea Kraits Sea Snakes

Sea Snake Distribution Sea Krait Distribution

Sea Snake Diets

Sea Snake Diving Aerobic dives average 13 minutes & 20 meters Anaerobic dives increase time by 30-45 min 2 hr max depth – ave > 50 m; 90 m max

Sea Snake Diving One elongate cylindrical lung that extends for almost the entire length of their body which is very efficient for gas exchange

Sea Snake Diving They are also able to carry out cutaneous respiration Oxygen diffuses from sea water across the snake’s skin into tiny blood vessels and carbon dioxide diffuses out

Venom! Sea snake venom is extremely toxic – neurotoxin + nasty enzymes lecithinase – lysis of eurythrocytes anticoagulase – delays or prevents blood cooagulation hyaluronidase – leads to diffusion of venom into cells Paralyzes prey; for defense Not usually aggressive – many victims on shore

Salt Removal Sea snakes are able to avoid excess salt accumulation from sea water using a salt excreting gland, the posterior sublingual gland that sits under the tongue Skin of sea snakes is very resistant to water, and does not let water in the snake easily One feature is that it does not resist water passage equally in both directions - allows the water to move inward faster than outward, thus giving it an advantage in the marine environment

Repro-man Like all snakes and lizards, male sea snakes have two penises – hemipenes Each is an autonomous independently functioning penis and only one is used during mating Mating takes place for long periods and sea snakes must surface for air during that time Diving 4 Images                                                                                                                

Born Free All sea snakes except the latidcaudids give birth to live young after gestation periods that range from four to eleven months Most species reproduce every year Timing of the reproductive cycle highly variable

Order Squamata Family Iguanidae Subfamily Iguaninae Marine, Fijian, Galapagos land, spinytail, rock, desert, green, and chuckwalla iguanas

Order Squamata Lizards are a widespread group of squamate reptiles, with nearly 3800 species Suborder Iguania - iguanas Suborder Gekkota - geckos Suborder Amphisbaenia – worm lizards Suborder Autarchoglossa – lizards, skinks, snakes

Subfamily Iguaninae Iguanas are lizards characterized by: Diurnal life history, Distinctive eyelids, External eardrums, Dewlaps (throat pouches), 5 toes on each limb with sharp claws, Herbivorous (unlike most lizards)

Marine Iguana Galapagos Marine Iguana (Amblyrhynchus cristatus) - Dark color (grey-black) helps absorb radiation from sun - ♂ more brightly colored: red, teal-green, and dull greenish - Adult ♂ are up to 1.7m (5.6 ft) long, ♀ 0.6–1m (2–3.3 ft), ♂ weigh up to 1.5 kg (3.3 lb).

Marine Iguana Laterally flattened tail, dorsal spines allow for efficient swimming Feed on marine algae Remove salt via salt glands in nose

Marine Iguana - ♀ lay 1-6 eggs in burrows dug 30-80cm deep - Eggs are laid in sand or volcanic ash up to 300m or more inland - ♀ guard the burrow for several days then leave the eggs to finish incubation (95 days)

Marine Iguana Can remain submerged for up to 60 min, though dives of 5 to 10 min are more common Iguanas spend much of their time restoring body heat ( from cold water) by sunning themselves on the rocks adjacent the shore

Order Crocodilia - Order of large reptiles – appeared 84 mya (late Cretaceous Period) - Closest living relatives of birds; two known survivors of the Archosauria Terrestrisuchus sp. – “land crocodile”

Order Crocodilia Family Gavialidae – Gharials Gharial (Gavialis gangeticus) Family Alligatoridae – Alligators & Caiman American Alligator (Alligator mississippiensis) Black Caiman (Melanosuchus niger) Family Crocodylidae – Crocodiles Saltwater crocodile (Crocodylus porosus)

Alligator & Crocodile Belong to two quite separate taxonomic families Alligators: Wider and shorter heads U-shaped snout Upper jaw wider than lower jaw Teeth in lower jaw fit into depressions in upper jaw Prefer freshwater Crocodiles: Narrow and longer head V-shaped snout Upper and lower jaws same width Crocodiles better tolerate seawater due to salt glands

Order Crocodilia Family Crocodylidae The saltwater or estuarine crocodile (Crocodylus porosus) is the largest of all living reptiles Marine habitats in Northern Australia, the eastern coast of India and parts of Southeast Asia

Saltwater Crocodile ♂ saltwater crocodile weighs 1,300 kg (3,000lb) and length can be 6m (20 ft) Greatest sexual dimorphism of any modern crocodilian; ♀ much smaller than ♂ India, S Pacific, Australia

Saltwater Crocodile Unlike other reptiles: Have a cerebral cortex, a 4-chambered heart, and functional equivalent of a diaphragm by incorporating muscles used for aquatic locomotion into respiration

Saltwater Crocodile Salt gland located in the mouth (modified salivary glands); salt is excreted through the tongue, spit out of the mouth