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

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

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