MARINE VERTEBRATES

MARINE VERTEBRATES REPTILES AND BIRDS

Transition to Land Acanthostega

Transition to Land • About 350 million years ago, vertebrates came onto land • Descended from bony fishes • Four problems these original land verts faced • must withstand the effects of gravity • must be able to breath air • must minimize water loss (dessication) • must adjust senses so they are suited for air instead of water

Gravity • Changes in skeleton to allow for support, protection of internal organs, shock absorption and distribution of weight • Air and breathing • Primitive lobe finned fish already had a type of lung. Was adapted to both intake O and remove CO2 • Desiccation • Watertight skin, amniotic egg, • Senses • Modifications of the eye and ear. Loss of the lateral line

Reptiles- Class Reptilia • Amniotic egg – large yolk for nutrition, leathery shell • Scales made of keratin • Most with 3-chambered heart • Ectothermic – produce little metabolic heat • Septum totally divides ventricle in crocodiles and birds (and likely dinosaurs); makes 4 chambered heart-more efficient circulation

Features in Marine Reptiles • Evolved from terrestrial reptile groups • Biggest anatomical hurdle is keeping internal salt concentrations low and not losing water • Salt glands- remove salt from their blood • Found above eyes • Salt excretions help conserve water and wash sand form their eyes • Concentrated urine to conserve water • Cannot drink sea water

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Marine Reptiles • Increase and reduce amount of air in lungs to allow diving and regulating buoyancy • Can tolerate anaerobic respiration and higher buildups of CO2 for longer dive times • Ectothermy- can regulate body temperature with behavior and changing habitat • Basking in sun, burying in mud, swimming in cold water

Orders of marine reptiles

Orders of Marine Reptiles • Testudines- turtles • 8 species and all are endangered • Diet mostly invertebrates and seaweeds • Squamata- Sea snakes and iguanas • All sea snakes are venomous • Only 1 species of iguana and only in the Galapagos • Crocodilia- • Only 1 species • Opportunistic predators

Birds descended from a reptilian ancestor

Birds-Class Aves • - Archaeopteryx - • - Feathers of keratin • - Lungs and air sacs near and in bones of back - • - Wall dividing ventricle is complete, two circulations do not mix • - Endothermic – body heat from metabolism • Requires eating a lot of food to maintain body temp. • - Amniotic egg with calcium carbonate for hardness

Features in Marine Bird • All birds have down feathers for insulation and contour feathers for flying • Powder feathers in marine birds repel water to protect down feather layer • Preening- some birds produce a special waterproofing oil that gets spread through their feathers • Denser bones in diving birds • All return to land to lay eggs • Webbed feet in swimming birds • Salt glands and concentrated urine

http://www.paulnoll.com/Oregon/Birds/feather-contour.html

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Types of Marine Birds • Seabirds- rely on the ocean for food or live on or near beaches and estuaries • Shorebirds • feeding in shallow water and water’s edge • Sandpiper, oystercatcher, red knot, egret, gull, duck • Diving shorebirds • Dive from the sky to catch food • Osprey, tern,pelican and some gull species • Diving pelagic birds • Fly long distances to find food • Albatross, storm petrel, auks, puffins • Penguins • Most aquatic of all marine birds • Flightless and good swimmers and divers • Only found in southern hemisphere

MARINE VERTEBRATES

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