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Key Concepts • The evolution of the amniotic egg gave reptiles a great reproductive advantage. • The Asian saltwater crocodile lives in estuaries and is adapted to life in the marine environment. • Sea turtles have streamlined bodies and appendages modified into flippers. • Sea turtles mate at sea and lay eggs on the same beaches where the females hatched. • Sea turtles may migrate long distances between their breeding grounds and their nesting beaches. • The marine iguana of the Galápagos Islands is the only marine lizard. • Sea snakes are mostly found in the shallow coastal waters of the Western Pacific and Indian oceans where they feed on fish and fish eggs. • Shorebirds are adapted for finding food in shallow water and sand. • A variety of bird species including, gulls, pelicans, and tubenoses are adapted to feeding on marine organisms. • Penguins are the birds most adapted to life in the sea. • Many marine reptiles and birds are endangered by human activities. Marine Reptiles • Ancestors of modern reptiles appeared about 100 million years ago. • Reptiles adapted for success on land, then used the same characteristics to return to the sea • Modern-day reptiles include: – crocodilians – turtles – lizards – snakes Amniotic Egg • An amniotic egg is covered by a protective shell – amnion – yolk sac – allantois – chorion • Amniotic egg allowed longs development with less risk of predation • Copulatory organs allow efficient internal fertilization Physiological Adaptations • Advanced circulatory system • Kidneys are efficient in eliminating wastes while conserving water • Skin covered with scales and lacking glands decreases water loss Marine Crocodiles • Largest living reptiles • Feed mainly on fishes • Drink salt water and eliminate excess salt through salt glands on their tongues • Lives along the shore, where it nests • Females reach sexual maturity at 10 – 12 years of age, males mature at ~ 16 years. • • • Elevated nests contain 40 – 60 eggs, incubation period is ~ 90 days Communicate with calls or barks Good navigational skills Sea Turtles • Seven species inhabit world’s oceans • Adaptations to life at sea – protective shells that are fused to the skeleton • outer layer composed of keratin • inner layer composed of bone • carapace • plastron – leatherback turtle lacks shell • Adaptations to life at sea – shell is adapted for buoyancy/swimming – fatty deposits and spongy bones add buoyancy – front limbs are modified into large flippers – back limbs are used for steering and digging nests • Behavior – generally solitary, interact for courtship – remain submerged (up to 3 hrs) while at sea – alternate between feeding and resting – sleep on the bottom under rocks or coral – in deep water, sea turtles can sleep on surface • Feeding and nutrition – have a beak-like structure instead of teeth – green sea turtle is the only herbivore – leatherback sea turtles adapted to eat jellyfish – salt consumed are eliminated as tears • Reproduction – courtship – nesting – female can lay several clutches of eggs – development and hatching • Turtle migrations – migrate hundreds to thousands of km – females return to beaches where they were born to nest – many hypotheses explaining method for sea turtle navigation over long distances: • utilize smell and taste as well as auditory cues • sense angle intensity of earth’s magnetic field • use sun • Sea turtles in danger – beach erosion/alteration – artificial lighting near nesting beaches – sea turtles are killed when trapped in fishing nests – – turtles are hunted by humans dogs, cats and raccoons dig up nests and prey on eggs Marine Iguana • The only marine iguana is in the Galápagos Islands • Most are black, some mottled red and black – absorption of heat – high body heat allows swimming and feeding in cold water – few predators but vulnerable to feral predators • Feeding and nutrition – herbivores with snout for grazing on seaweed – some dive at high tide to feed on algae – excess salt excreted by specialized glands • Behaviors – good swimmers – intruders are attacked when they enter territory • rarely result in serious injury Sea Snakes • Descendants of lizards • Adaptations to life in the sea – scales – tail – nostrils – single lung – exchange gases through the skin – can lower metabolic rate to use less O2 • Feeding and nutrition – eat mainly fish, fish eggs and eels – salt excreting gland • Reproduction – 3 oviparous species, others are viviparous – congregate to mate – have two penises - hemipenes – gestation from 4 to 11 months – can swim at birth • Sea snakes and humans – venom is toxic – rarely bite humans – eaten in Japan Seabirds • 250 of 8,500 bird species live near or in the sea • Seabirds feed in the sea • Some spend months away from land • Types of seabirds: – – – – – shorebirds gulls and their relatives pelicans and their relatives tubenoses penguins Adaptations for Flight • Homeothermic • High rate of metabolism • Strong muscles, quick responses and coordination • Advanced respiratory system with 4-chambered heart • Excellent sight and hearing and large brain Adapting to Life in the Sea • Large amounts of salt are consumed – salt glands remove excess salt – tears have high salt concentration Shorebirds • Oystercatchers – oystercatchers use long, orange bills to slice through adductor muscles of bivalve molluscs, pry limpets off rocks, crush crabs and probe mud • Plovers – have short, plump bodies – nests in depressions or hollows on the ground • Turnstones – heavyset birds, with upturned bills used like crowbars to turn over stones and beach debris • Sandpipers – feed on small crustaceans and mollusks in sand • Curlews – long-billed curlew uses bill like a forceps to extract shellfish from their burrows • Avocets and Stilts – have long legs and necks and slender bodies – avocets wade through shallow water, moving beak the water – stilts probe the mud for small animals • Herons, egrets and bitterns – widespread – skinny legs and long necks – most stand still and wait for prey – some stalk prey or frighten prey into motion Gulls and Their Relatives • Gulls have webbed feet and oil glands • They are not true ocean-going birds • • • • • • • Have enormous appetites but are not selective feeders Relatives of gulls include terns, skuas, jaeger birds, skimmers and alcids Gulls – herring gulls are the most widespread – feeding • noisy, aggressive, efficient predators and scavengers • may drop prey to break the shell open • highly successful at finding food – nesting • highly gregarious; gather in large colonies • not picky about nesting sites or materials • both sexes assist in incubating 2-3 eggs • chicks hatch in 3-4 weeks • not uncommon for only 1 out of every 5 hatchlings to survive Terns – small birds with brightly-colored bills and forked tails – hunt by plunging into the water; will steal food – usually gregarious nesters Skuas and Jaegers – very aggressive omnivores and predators – “hawks” or “vultures” of the sea – jaegers will pursue other birds to steal their prey Skimmers (scissorbills) – pupils that are vertical slits and a – lower jaw protruding farther than the upper bill – fly over water and create ripples that attract fish Alcids - include auks, puffins and murres – look like penguins but are related to gulls • convergent evolution • ecological equivalents – nesting and reproduction • alcids gather in dense, cliff side colonies • both parents care for 1 pear-shaped egg – parental care of the young • young murres plunge into the water to be joined by the parents • alcid parents spend most of their time gathering food for chicks • adult puffins abruptly leave chicks to learn to swim after 6 weeks of constant care Pelicans and Their Relatives • Pelicans, gannets, boobies, cormorants, darters, frigatebirds, tropicbirds • Have webs between all 4 toes • Upper mandible is hooked in pelicans, cormorants and frigatebirds • Many are brightly colored, or have head adornments • Pelicans – – – • • • large birds preferring warm latitudes and estuary, coastal and inland waters require a large fish population feed just under the water’s surface • gular pouch Boobies – dive into the sea from 18-30 m up to fish – numbers of eggs may reflect food supply Cormorants – lack oil glands, must periodically dry their wings Frigatebirds – lightweight body and near 2 m wingspan – cannot waterproof their feathers – hence they feed by skimming surface with their bills – pursue/attack other birds to steal prey Tubenoses • Petrels, albatrosses and shearwaters • Tubular nostrils on their beaks • Glands secrete concentrated salt solution • Glands in stomachs produces oil used for feeding hatchlings and defense • Albatrosses – gliders with wings nearly 3.5 m long – most live in the Southern Hemisphere – usually come to land only to breed – elaborate courtship displays precede mating – 1 egg is incubated by both • Petrels – small birds with long legs with fluttering flight • feed with legs extended and feet paddling rapidly • form long-term pair bonds for breeding • live only in year-round cold water • spot prey from the air, dive, and pursue prey by “flying” underwater Penguins • Swift swimmers – streamlined – flat, webbed feet for steering – leap from the water to breathe • Eat fishes, squid and krill • Eaten by leopard seals and killer whales • Female emperor penguin lays 1 egg, which the male incubates while she feeds – egg sits on his feet, covered by a fold of skin – male can feed the chick – crop – both parents help – by summer, the chick can feed itself,