Marine Animals-Key Ideas
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Marine Animals-Key Ideas * Animals are active, multicellular organisms incapable of synthesizing food. * The invertebrates and vertebrates are grouped by similarities in external appearance and internal architecture into phyla. * All vertebrates belong to the phylum Chordata. The most abundant and diverse vertebrates are the fish. * Invertebrates are generally soft-bodied organisms lacking a rigid internal skeleton. Many possess a hard outer protective covering * Each marine phylum has developed a set of adaptations, characteristics that allow it to survive in its environment. 1 The Origin of Animals Between 2 billion and 400 million years ago, photosynthetic autotrophs changed the composition of the atmosphere, making the evolution of 2 animals possible. 1 Invertebrates Invertebrates are soft-bodied animals. Many invertebrates have a hard protective covering (e.g., snails or lobsters). There are at least 33 phyla of invertebrates, and most of these phyla are represented 3 among marine life. Invertebrates 4 An upright sponge, a member of phylum Porifera. 2 Invertebrates The clam, snail, and squid are examples of the phylum Mollusca and 5 class: Bivalvia (clam), Gastropoda (snail), and Cephalopoda (squid). The Chordates Chordata is the most advanced animal phlyum. All chordates have, at some time during development, a notochord. In some chordates the notochord is lost during development. These are the invertebrate chordates. Most chordates (about 95%) retain the notochord in some form. These are the vertebrate chordates. Both invertebrate and vertebrate chordates are represented in ocean environments. 6 3 Vertebrate Evolution and Classification One proposed family tree for the vertebrates and invertebrate chordates. 7 Cartilaginous Fishes 8 4 Commercial Bony Fishes 9 Figure 16.15 Deep Sea Fishes 10 5 The Problems of Fishes Movement, shape and propulsion - fish must be able to move through water, which is 1,000 times denser and 100 times more viscous than air Maintenance of level - fish tissue is usually denser than the surrounding water, so fish must have a system to keep from sinking Gas exchange - the problem of extracting oxygen from water Osmotic considerations - fish need a system to maintain proper salt levels in their bodies Feeding and defense - competitive pressure among a large number of fish has caused a wide variety of feeding habits to evolve 11 The Problems of Fishes How body shape affects movement. 12 6 Osmotic Considerations Osmoregulation in freshwater and saltwater fishes. 13 Depletion of fishes at various depths 14 7 Overshoot and Collapse Atlantic Cod Catch Atlantic Haddock Catch 60 80 50 s n 60 Tons To 40 tric Metric Me 30 40 d n a s 20 u o 20 Thousand Th 10 0 0 1950 1960 1970 1980 1990 2000 1950 1960 1970 1980 1990 2000 15 Overshoot and Collapse Atlantic Swordfish Catch 5 Pacific Bluefin Tuna Catch 16 4 Tons 12 3 Metric 8 2 Thousand Metric Tons 4 Thousand 1 0 0 1950 1960 1970 1980 1990 2000 1950 1960 1970 1980 1990 2000 16 8 Repeated Cycles of Overshoot and Collapse Peruvian Herring, Sardine, and Anchovy Catch 14 12 10 ons T 8 Metric 6 Million 4 2 0 1960 1970 1980 1990 2000 17 Anchovy Catch of Peru and Ecuador 18 9 Sustained Catch (So Far) Australian Lobster Catch Norway Cod, Hake, Haddock Catch 20 1,400 1,200 s 15 n o 1,000 T tric 800 Me 10 d n 600 a s u o h 400 T Thousand metric tons 5 200 - 0 1960 1970 1980 1990 2000 1960 1970 1980 1990 2000 19 Marine Reptiles Marine reptiles are ectothermic, breathe air with lungs, have scales and relatively impermeable skin, and are equipped with special glands to maintain salt balance. Marine reptiles include: • Sea turtles • Marine crocodiles • Sea snakes 20 10 Marine Reptiles 21 Marine Birds Only 270 of the known species of birds qualify as seabirds. Seabirds have salt excreting glands to eliminate salt taken in with their food. There are four groups of seabirds: Tubenoses - this group includes the albatrosses and petrels Pelicans - this group includes relatives of the penguins that have webbed feet and throat pouches Gulls - these birds are found along the shore, where they scavenge for food. Penguins - these birds have lost the ability to fly, but are excellent swimmers 22 11 Marine Mammals Cetacea – porpoises, dolphins and whales Carnivora - seals, sea lions, walruses and sea otters Sirenia – manatees and dugongs 23 Figure 16.5 24 12 Sea Cows 25 Figure 16.3 26 13 Marine Mammals A few of the marine mammals of the Order Cetacea. Suborder Mysticeti (mystidos = unknowable) whales are known for having no teeth and instead use baleen for filter feeding. 27 Marine Mammals A few of the marine mammals of the Order Cetacea. Suborder Odontoceti (odontos = tooth) whales are known for being active predators who use teeth for feeding. The toothed whales search for food using echolocation, a biological equivalent to sonar. 28 14 Figure 16.2 29 30 15 Echolocation 31 Summary Marine animals have evolved effective adaptations for capturing prey, avoiding danger and maintaining thermal and fluid balance with their environment. (above) An example of echolocation, used by toothed whales to locate their prey. 32 16.