1. Marine Vertebrates: Lecture 5
Marine Reptiles

3. Amniote relationships

4. Class Reptilia: Diversity
Testudines (Turtles)
Evolutionary relationships uncertain
Sphenodontia (Tuataras)
Only found on New Zealand
Believed to be oldest order
Crocodilia (crocs, alligators)
Largest reptiles
Closely related to dinosaurs
Squamata (Snakes and lizards)
Most numerous and diverse group

5. Reptilian Adaptations Implications for marine existance
Amniotic egg:
Waterproof/breatheable
Laid on land
Keratinized scales
Waterproofing
Well-developed kidney
Why important to marine reptiles?
Well-developed respiratory system
Breath-holding/oxygen conservation
Circulatory system
Some division into pulmonary and systemic
Internal fertilization
Shell covering added post- fertilization

6. Indo-Pacific Crocodile
Photo: John Wattie

7. Indo-Pacific Crocodile Adaptations to aquatic envirnoment
Laterally-flattened tail (aquatic propulsion)
Able to open their mouths while underwater
How do they keep water out of lungs and nostrils?
How do they deal with pressure change in ears?
Salt glands: modified salivary glands
Indo-Pacific (Australian) crocodile, Crocodylus porosus, is estuarine. (= “salt water croc”)
Largest specimens: 10 meters long
Primarily feeds on fish, may feed on mammals.
No crocodiles fully adapted to marine existence.

8. Marine iguana Galapagos Seven subspecies Close relative of land iguana
Marine iguana, Galapagos Photo: mongabay.com
Land iguana, Galapagos Photo: Rod Eime

9. Marine iguana Adaptations to aquatic envirnoment
Jaw/teeth
Short snout, three-cusp teeth are adapted for feeding on algae
Secrete excess salt via salt glands
Beneath eyes, connect to nostrils
“Sneezing” = salt excretion
Laterally flattened tail
Swimming posture?
Feet: webbed, long claws
Cling to rocks in surf
Submerge up to 15 meters, 30 minutes
Marine iguana Photo: Gary Benson

10. Marine iguana Other features of interest
Huddle at night (why?)
Body shrinkage during El Niño
Related to shift in algal types
Territoriality and mating behavior
NOTE: Other iguana species are part of marine food web
Green iguana (Iguana iguana): Caribbean
Why not considered “marine”?

11. Sea snakes Overview Marine adaptations Family Hydrophiidae
Cobra relatives (F. Elapidae)
Tropical Indo-Pacific (most)
Evolved from land snakes
Pelagic sea snake
Photo: Zoltan Takacs
Marine adaptations
Laterally flattened
Nostril valves/ enlarged mouth scales
Enlarged left lung
Functions?
Salt glands (mouth)
Lack enlarged ventral scales
Why relavant?
Bear live young at sea

12. Sea snakes Other features Venomous Feeding? Aggregation Not aggressive
Pelagic sea snake
Photo: Zoltan Takacs

13. Sea krait (Family Lacticaudidae)
Photo: Nick Hope
Less adapted to marine environment
Enlarged belly scales
Lay amniotic eggs on land

14. Coming soon to a Marine Vertebrates class near you…
Sea turtles!
Hawksbill turtle: Photo: Karen Haberman