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Chapter 11
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Chapter 11

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  1. Reptiles and Birds Chapter 11

  2. 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.

  3. Key Concepts • 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. • Sea turtle populations are endangered by a number of human endeavors.

  4. Key Concepts • The marine iguana of the Galápagos Islands is the only marine lizard. • Several species of venomous sea snake live in the marine environment. • Shorebirds have long legs for wading and thin, sharp bills for finding food in shallow water and sand.

  5. Key Concepts • 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.

  6. Marine Reptiles • Reptiles adapted for success on land, then used the same characteristics to return to the sea and gain success there as well • Modern-day reptiles include: • crocodilians • turtles • lizards • snakes

  7. Amniotic Egg • An amniotic egg is covered by a protective shell and contains: • amnion—a liquid-filled sac in which the embryo develops • yolk sac—sac where yolk (food) is stored • allantois—sac for disposal of waste • chorion—a membrane lining the inside of the shell which provides a surface for gas exchange during development • Copulatory organs allow efficient internal fertilization

  8. Physiological Adaptations • Advanced circulatory system in which circulation through the lungs is nearly completely separate from circulation through the rest of the body • more efficient method of supplying oxygen • Kidneys are efficient in eliminating wastes while conserving water • Skin covered with scales and lacking glands decreases water loss

  9. Marine Crocodiles • Best adapted to the marine environment is the Asian saltwater crocodile (Crocodylus porosus) • Large animals (up to 6 m long) • Feed mainly on fishes • Drink salt water and eliminate excess salt through salt glands on their tongues • Lives along the shore, where it nests

  10. Sea Turtles

  11. Sea Turtles • Adaptations to life at sea • protective shells that are fused to the skeleton and fill in the spaces between the vertebrae and ribs protect their bodies • outer layer of shell composed of keratin • inner layer composed of bone • carapace—dorsal surface of the shell • pastron—ventral surface of the shell • leatherback turtle lacks shell and has a thick hide containing small bony plates

  12. Sea Turtles • Adaptations to life at sea (continued) • shell is flattened, streamlined,d reduced in size and weight, for buoyancy/swimming • large fatty deposits beneath the skin and light, spongy bones add buoyancy • front limbs are modified into large flippers • back limbs are paddle shaped and used for steering and digging nests

  13. Sea Turtles • Behavior • generally solitary, don’t interact • remain submerged while at sea; breathe air but can stay under water for as long as 3 hours • alternate between feeding and resting during the day • sleep on the bottom under rocks or coral

  14. Sea Turtles • Feeding and nutrition • have a beak-like structure instead of teeth • green sea turtle is the only herbivore • leatherback sea turtles eat jellyfish • pharynx is lined with sharp spines to hold slippery prey • digestive system adapted to withstand stings • large amounts of salt consumed with food and water are eliminated as concentrated tears through salt glands above the eyes

  15. Sea Turtles • Reproduction • courtship – males court females before mating; males may compete for a female, or 1 female may mate with several males • nesting – females dig shallow pits on the beach, usually at night, and bury eggs • development and hatching • temperature determines development time and sex ratio • hatchlings rush for the safety of the sea after hatching

  16. Sea Turtles • Turtle migrations • females migrate from feeding grounds to the beaches where they were born to nest • green sea turtles feed on grasses in warm, shallow continental waters, but breed on remote islands • some breed on a 2- or 3-year cycle • method for navigation over long distances is unknown

  17. Sea Turtles • Sea turtles in danger • beach erosion • artificial lighting near nesting beaches • sea turtles are killed when trapped in fishing nests, especially those used for shrimpers • turtle exclusion devices can reduce turtle mortality by as much as 95% when used for shrimp nets • turtles are hunted by humans for meat, eggs, leather and shells

  18. Marine Iguana • The marine iguana of the Galápagos Islands off Ecuador is the only marine lizard • Most are black, but some are mottled red and black • dark coloration is thought to allow more absorption of heat energy • raising body temperature allows them to swim and feed in cold Pacific waters

  19. Marine Iguana • Feeding and nutrition • herbivores with a short, heavy snout for grazing on dense mats of seaweed • swallow small stones to reduce buoyancy for feeding under water • excess salt from consumed seawater is extracted and excreted by specialized tear and nasal glands

  20. Marine Iguana • Behaviors • good swimmers, using lateral undulations of the body and tail • each male occupies a small territory on the rocks, usually with 1 or 2 females • intruders or challengers are attacked when they enter the male’s territory • fights between male iguanas rarely result in serious injury

  21. Sea Snakes • Adaptations to life in the sea • scales are absent or greatly reduced for streamlining • tail is laterally compressed into a paddle • nostrils are higher on the head • valves in the nostrils prevent water from entering when the snake is submerged • single lung reaches to the tail, and trachea is modified to act as an accessory lung by absorbing oxygen

  22. Sea Snakes • Adaptations to life in the sea (cont.) • can exchange gases through the skin while under water • can lower metabolic rate to use less O2 • Feeding and nutrition • eat mainly fish and eels, sometimes eggs • most ambush prey and strike with venomous fangs • can swallow prey more than twice their diameter

  23. Sea Snakes • Reproduction • 3 oviparous species lay eggs on land • others are viviparous, with females retaining the eggs within their bodies until they hatch; young can swim at birth • Sea snakes and humans • sea snake venom is toxic to humans • being timid, sea snakes rarely bite humans; people eat them in Japan

  24. Seabirds • 250 of 8,500 bird species are adapted to live near or in the sea • Seabirds feed in the sea • Some spend months away from land, but all must return to land to breed • Types of seabirds: • shorebirds • gulls and their relatives • pelicans and their relatives • tubenoses • penguins

  25. Adaptations for Flight • Homeothermic—maintaining a constant body temperature • Feathers aid in flight and insulate • High rate of metabolism to supply energy for active flight/nervous system • Strong muscles, quick responses, great deal of coordination • Advanced respiratory system with 4-chambered heart • Keen senses

  26. Adapting to Life in the Sea • Large amounts of salt are consumed with food and salt water • salt glands above the eyes produce tears to remove excess salt • these tears have twice the salt concentration of seawater

  27. Shorebirds • Waders with long legs and thin, sharp bills used to feed on intertidal organisms • Oystercatchers, curlews & turnstones • oystercatchers use long, blunt, vertically-flattened orange bills to slice through adductor muscles of bivalve molluscs • long-billed curlew uses its bill like a forceps to extract shellfish from burrows

  28. Shorebirds • heavyset turnstones use slightly upturned bills as crowbars to turn over stones, sticks and beach debris in search of food • Plovers • have short, plump bodies with bills resembling a pigeon’s, and are shorter than other waders • have nests characteristic of waders, built in depressions or hollows on the ground

  29. Shorebirds • Avocets, stilts, and sandpipers • avocets and stilts have very long legs, elongated necks, and slender bodies • avocets wade through shallow water, moving a partially opened beak from side to side through the water, to feed • stilts probe the mud for small animals (e.g. insects, crustaceans) with their bills • sociable sandpipers feed on small crustaceans and molluscs as the surf retreats

  30. Shorebirds • Herons (e.g. egrets and bitterns) • most stand still and wait for prey to come in range to feed • some stalk prey or stir up the bottom to frighten prey into motion so it can be caught

  31. Gulls and their Relatives • Gulls have webbed feet and oil glands to waterproof their feathers • They are not true ocean-going birds, and do not stray far from land • Have enormous appetites • Are not very selective feeders • Relatives of gulls include terns, skuas, jaeger birds, skimmers and alcids

  32. Gulls and their Relatives • Gulls • herring gulls are the most widespread, and are vocal, gray and white, and travel in large groups • feeding • noisy, aggressive, efficient predators and scavengers • may drop prey with hard shells on rocks or parking lots to break the shell open • highly successful at finding food and surviving

  33. Gulls and their Relatives • Gulls (continued) • 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, and remain in the nest until almost fully grown, camouflaged by speckled down • chicks are vulnerable to predation by other animals and by other gulls

  34. Gulls and their Relatives • Terns • small, graceful birds with brightly-colored and delicately-sculpted bills, forked tails • hunt by plunging into the water for fish and invertebrates; 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

  35. Gulls and their Relatives • Skimmers (scissorbills) • small birds with pupils that are vertical slits and a flexible lower jaw protruding much farther than the upper bill • fly over water and use the lower bill to create ripples at the water’s surface that attract fish • fish are then collected by flying along the same path over the water a second time

  36. Gulls and their Relatives • Alcids (e.g. auks, puffins, murres) • look like penguins but are related to gulls • convergent evolution—similar selective pressures brought about similar adaptations in unrelated groups of animals • ecological equivalents—different groups of animal that have evolved independently along the same lines in similar habitats, and therefore display similar adaptations • major difference is that alcids can fly