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Marine Reptiles, Birds, and Mammals Chapter 9 2 Marine Reptiles • Reptiles- have the ability to lay eggs on land, and they have scaly skin to prevent water loss. • Reptiles are ectotherms, so they are more common in temperate and tropical seas. • Reptiles have lungs, so they must surface to breathe. 3 Sea Turtles- Order Chelonia • Like land turtles- have a protective carapace fused to their backbones. • Unlike land turtles, they cannot retract their heads and limbs into the shell. • There are nine species- all are endangered or threatened. • Live primarily in warm waters. • Must return to land to reproduce. 4 Sea Turtles (cont’d) • Green sea turtles- live in coastal waters, feed on • • • • • seaweeds and seagrasses. Nest every 2-4 years on the same beaches. DNA tests show similarities in populations from specific breeding grounds. Baby sea turtles must cross the beach to get to the sea. Many predators such as crabs, dogs, shorebirds. Temperature of nest determines sex of baby sea turtles. 5 Adult Sea Turtles 6 Green Sea Turtle 7 Hawksbill turtle 8 Loggerhead sea turtle 9 Baby Sea Turtles are called hatchlings 10 Sea Turtle nest hatching 11 The dangerous trip to the sea! 12 Other marine reptiles • Sea Snakes- Order Squamata. • They are carnivores and eat small fish and their eggs. • Bear live young- they are ovoviviparous, carrying their eggs until hatching. • Live a totally marine existence- have a laterally compressed body for swimming. 13 Yellow Lipped Sea Snake 14 Sea Snake 15 Other Marine Reptiles- cont’d • Marine Iguanas- Live only in the Galapagos Islands. • Lives mostly on the rocky shores of these islands- dives and swims to feed on seaweeds. • Saltwater crocodiles- live in estuaries and mangroves in the Indian Ocean, Australia, and the west Pacific. • Very Aggressive- known to attack humans 16 Galapagos marine iguana 17 Galapagos Marine Iguana 18 The White ‘wig’ is made of salt ! 19 Seabirds • Birds (Class Aves) are homeotherms- they maintain a constant internal temperature. • Seabirds are any bird that feeds on marine organisms. • They must nest on land. • They are only ~3% of all bird species. • They require a LOT of energy!!!! 20 Penguins • Flightless birds with wings modified into ‘flippers’ • Have a layer of fat for insulation and waterproof • • • • • feathers. Live only in the southern hemisphere. Many travel for miles to reach inland breeding grounds. Only the Galapagos penguin lives at the equator. They hunt in the ocean for fish, krill, and squid. Ex.- Emperor’s, Chinstraps, Adelie, Galapagos 21 Emperor penguin chicks 22 Adult Emperor Penguins 23 Adelie Penguins 24 Chinstrap Penguins 25 Galapagos Penguins 26 Tubenoses- Albatrosses and Petrels • Can spend months or years at sea, only return to land to breed. • Have salt glands on their beaks for excreting excess salt • Albatrosses- have the longest wingspan of any bird- up to 11 ft! • Albatrosses and other tubenoses, mate for life. • Petrels and shearwaters are also in this group 27 Northern Royal albatross, and Wandering albatross with chick. 28 Waved Albatross 29 Shearwaters flock by the thousands for a feeding frenzy 30 Buller’s Shearwater- off the coast of New Zealand 31 Pelicans, Cormorants, and Frigates • Pelicans- dive and scoop fish out of the water into a pouch. • Once threatened by pesticide use (DDT) • Cormorants- black birds that dive and • chase their prey. They sit low in the water, can sometimes be seen drying their wings on docks • Frigates- rarely touch the water, they steal food from other seabirds midflight. 32 Brown Pelicans 33 Frigate birds- male displaying for females 34 Cormorants 35 Gulls and terns • Gulls live in all 50 states, the most widely distributed bird in North America. • Gulls are scavengers and predators. • They often will prey upon the nests and young of other birds. • Terns- Small graceful flyers, they hunt by plunging into the water for small fish. 36 37 38 Arctic Terns travel from the Arctic, where they breed, to the Antarctic for feeding during the summer- a yearly migration of over 24,000 miles! 39 Common Tern and chicks 40 Shorebirds • Group that includes sandpipers, plovers and all birds that live on the beach or inlets. • Often live in inland freshwater habitats as well. 41 American Oystercatcher 42 Least Sandpiper- Monterey Bay, CA 43 Piping Plover- a threatened species 44 Beak shape in birds is related to its food supply and how it hunts 45 46 47 Figure 9.08 48 Marine Mammals • Mammals are homeotherms. • Have hair instead of feathers for insulation. • They are viviparous, and nurse their young. • Have a large brain compared to their body size. • Five groups (orders and suborders) of mammals inhabit the oceans 49 Order Pinnipedia • Seals, sea lions, and walruses. • Closely related to the carnivora (cats, dogs, bears) • Predators-Feed on fish and squid. • Live in cold waters. Have blubber for insulation. • Blubber also serves as a food reserve and aids in buoyancy. 50 Pinnipeds (cont’d)- Seals • Seals- have posterior flippers that cannot turn forward. • Harbor seals are the most common in the North Atlantic and Pacific. • Monk seals are a rare warm water species. • Elephant seals- can be 4 tons. • Seals have been hunted for their meat and oil, but are now protected in the U.S. 51 Figure 9.09b 52 Baby Harp Seals 53 Pinnipeds (cont’d)- sea lions • Sea lions have external ears and can move their flippers forward. • They can move more easily on land. • California Sea Lion is the most common. • Fur seals have been hunted extensively for their thick fur. • Walruses- feed on clams and other benthic invertebrates. Easily identified by their large tusks 54 55 Fur Seal 56 California Sea Lion 57 South American Sea Lions 58 Walruses have tusks for defense and anchoring to the ice. 59 60 Order Carnivora- Sea Otters • The smallest marine mammal. • The only marine mammals that lack a layer • • • • of blubber. Insulation by trapping air in the thick fur. Were at one time almost hunted to extinction. They breed and give birth in the ocean. They live in kelp forests and are an important part of the kelp forest ecosystem. 61 Sea Otters are playful marine mammals. 62 Sea Otters 63 Order Sirenia- manatees • Have front flippers but no rear limbs. • Strict vegetarians- feed on seaweeds and grasses. • Have been hunted to near extinction (the Stellar’s sea cows are extinct) • Seagrass beds threaten their food supply. • Often injured by boats, all four species are endangered. 64 65 The Florida Manatee is protected under the Marine Mammal Protection Act. 66 Mother and calf- Manatees only produce one calf every three years. 67 Order Cetacea- Whales, dolphins and porpoises • Cetaceans have made the greatest transition to marine living. • Their bodies are a streamlined shapesimilar to fish. • Convergent evolution- when different species evolve similar characteristics due to similar lifestyles or environments. 68 Convergent evolution in marine vertebrates 69 Order Cetacea • Have front flippers- rear limbs have • • • • disappeared. Rear limbs exist only in early embryonic stages. Instead of a caudal fin, cetaceans have a pair of horizontal flukes. Have almost no hair, but have blubber for insulation. Nostrils have moved to the top of the head. 70 71 Early cetacean embryo 72 Baleen whales- Suborder Mysticeti • Toothless whales- have rows of flexible, fibrous plates that hang from upper jaws. • Made from Keratin, and have overlapping hair-like bristles. • Filter feed by taking a large mouthful of H2O and forcing it out through the baleen. • The whale then licks the trapped food off the bristles. 73 Filtering apparatus in a baleen whale (Suborder Mysticeti) 74 Baleen Whales- Cont’d • They are the largest of all whales, and the largest animals ever to live on earth. • Blue whales- average 80 ft long, 90-140 tons. (Record is 110ft, and 200 tons!) • Rorquals- baleen whales that have an expanding lower throat to feed on schools of krill. Ex- Blue, fin, minke, and humpback whales. 75 Baleen Whales- Cont’d • Right whales and bowhead whales- Have fine bristles that can catch copepods as well as krill. • Grey whales- bottom feeders, eat squid and amphipods. 76 Blue whale- a rorqual 77 Humpback whale 78 Grey whale 79 Minke Whale 80 Right whale 81 Bowhead Whale 82 83 Toothed Whales- Suborder Odontoceti • Orcas, dolphins, porpoises. • Teeth are used for catching prey, not chewing. • Food is swallowed whole, then ground up in a three chambered stomach. • Sperm whale- the largest toothed whale, feed on squid, and are the deepest diving whales. 84 Toothed Whales- cont’d • Orcas- killer whales that feed on seals and sea lions. • Dolphins and porpoises- smallest of toothed whales. • *Porpoises are smaller and have blunt noses. • They often travel in groups called pods. 85 Orcinus orca 86 Tursiops truncatus 87 Phocoena phocoena- harbor porpoise 88 Harbor porpoise 89 Biology of Marine Mammals • Difficult to observe- many do not survive well in captivity. • Swimming- streamlined body- up and down motion of tail and flukes. • Fastest speed recorded- 40mph in common dolphins! 90 Common dolphins 91 92 Up and down swimming motion of cetaceans 93 Breathing- the trick to cetacean survival • Blowhole- on top of the head. • Cetaceans breathe very quickly to avoid drawing • • • in water. Fin whales can exhale and inhale 3000 times as much air as we can in only 2 seconds!!! Condensation of water vapor in the breath and seawater creates a distinctive spout. this plus diving patterns can help identify whales from a distance. 94 95 More on diving • Cetaceans have blubber to prevent heat loss. • Mouths exposed to cold - network of blood vessels in the tongue helps prevent heat loss though the mouth. • Most marine mammals make very long dives. 96 Dive times • Sea otters- 4-5 minutes- not too deep. • Pinnipeds- usually up to 30 minutes. • Weddell seal- can dive for over 1 hour! • Cetaceans- dive for ~ one hour. • baleen whales- feed on plankton• shallow divers. toothed whales- dolphin dive up to 990ft, sperm whales up to 7380!!!! 97 How do they do it?- Several crucial adaptations! • 90% gas exchange- compared to 20% in humans. • They have more blood than non-diving mammals. • Blood has a higher concentration of Red blood cells, which have more hemoglobin than land mammals. • Muscles have more myoglobin- their muscles can store oxygen. 98 Marine mammals can reduce oxygen consumption. • They can slow their heart rate when they dive. • They can reduce blood flow to nonessential parts of the body. • Nitrogen- their lungs collapse when they dive, which prevents excess nitrogen from dissolving into the blood. (which causes the ‘bends’) 99 Echolocation- natures sonar • Used to find prey and orient themselves in their surroundings. • They emit sounds waves, and interpret the sounds reflected back from objects. • The time for echo return tells them distance. • Very precise- dolphins can distinguish between very similar objects. 100 Echolocation (cont’d) • Clicks and whistles produced by air sacs in the head. • Melon- fatty structure on the head of toothed whales- believed to be involved with focusing and directing sounds. • Echoes are picked up by the lower jaw, transmitted to inner ears and then the brain. 101 Biology of echolocation 102 The melon gives this beluga whale its rounded forehead. 103 Communication • Very prominent in social groups of pinnipeds. • In cetaceans- very complex sounds indicate mood, mating signals, and can identify a species. • Humpback whales- sing a very distinct song during mating season- can repeat the same song for days. 104 Behaviors • Play behavior- many cetaceans play with food or floating objects. • Breaching- leaping into the air, and loudly crashing on the surface. • Why?- perhaps to attract mates, remove parasites, scan the shoreline. • Spying behavior- lifting their heads out of the water to view the surface. 105 Some whales will surround and protect an injured member of their pod. 106 Spying behavior in orcas 107 Pilot Whale “Spying” 108 Grey Whale ‘Spy hopping’ 109 Dolphins helping an injured companion to the surface to breathe. 110 Beaching • No one is quite sure why cetaceans beach themselves. • Could be following an injured or sick pod member. • Could be linked to high-intensity sonar used by military. • Caused hemorrhages in inner ears, and rapid surfacing causes the bends. 111 56 Pilot whales beached on Cape Cod, 2002 112 Migration • Many great whales migrate thousands of miles to mate or to feed. • Baleen whales- feed at the poles during the summer, migrate to warmer waters in winter to breed. • Spying behavior very common in migrating whales. 113 Figure 9.31 114 Reproduction in pinnipeds • Pinnipeds- male seals usually mate with only one female. • Elephant seals and sea lions- breed in harems, with one dominant male defending his female group. • Delayed implantation- embryo goes dormant in order for the timing of the pups to coincide with the migration to breeding grounds. 115 Stellar sea lions and California sea lions at their breeding grounds 116 Mother and pup 117 Reproduction in cetaceans • Gestation is usually 11-12 months, to • • • • coincide with migration patterns. It takes- 9 months to develop a 7lb human. 11 months to develop a 3 ton blue whale calf! Cetaceans are born tail first to allow extended time to receive oxygen from the placenta. Blue whale calves can gain 200 lbs and grow 1.5inches a day for the first 7 months! 118 Figure 9.35 119 120 121 Table 9.02 122 Table 9.01 123