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

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

3. 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

4. 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

5. 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.

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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.

13. 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

14. 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

15. 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

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

17. 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

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

20. Sea Kraits
Sea Snakes

21. Sea Snake Distribution
Sea Krait Distribution

22. Sea Snake Diets

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

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

25. 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

26. 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

27. 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

28. 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
                                                                                                               

29. 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

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

31. 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

32. 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)

33. 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).

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

35. 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)

36. 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

37. 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”

38. 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)

39. 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

40. 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

41. 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

42. 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

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