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Marine Vertebrates: Lecture 5

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1 Marine Vertebrates: Lecture 5
Marine Reptiles

2

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


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