Marine Reptiles

Marine Vertebrates: Lecture 5

Amniote relationships

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

Class Reptilia: Diversity

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

Indo-Pacific Crocodile

Photo: John Wattie

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.

Land iguana, Galapagos Photo: Rod Eime

Marine iguana, Galapagos Photo: mongabay.com

Marine iguana• Galapagos

• Seven subspecies

• Close relative of land iguana

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

Marine iguanaOther 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”?

Sea snakes• Overview

Family Hydrophiidae•Cobra relatives (F. Elapidae)

Tropical Indo-Pacific (most)

Evolved from land snakes

•Marine adaptations Laterally flattened Nostril valves/

enlarged mouth scales

Enlarged left lung •Functions?

Pelagic sea snakePhoto: Zoltan Takacs

Salt glands (mouth) Lack enlarged

ventral scales•Why relavant?

Bear live young at sea

Sea snakes• Other features

Venomous•Not aggressive

Feeding? Aggregation

Pelagic sea snakePhoto: Zoltan Takacs

Sea krait (Family Lacticaudidae)

• Less adapted to marine environment Enlarged belly scales Lay amniotic eggs on land

Sea kraitPhoto: Nick Hope

Coming soon to a Marine Vertebrates class near you…•Sea turtles!

Hawksbill turtle: Photo: Karen Haberman