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Oceanography Chapter 15: Marine Animals Heterotrophic – cannot synthesize their own food Eat autotrophs or lower level heterotrophs True multicellular critters arose 700-900 MYA (Proterozoic Eon) >about 2 BY after cyanobacteria put out enough free oxygen into the atmosphere ¾ O2 Revolution - 1% to 20 % in 1.5 BY ¾ O3 formed – allow for critters to leave the water 400 MYA Early views of life Burgess Shale of B.C. “It’s a Wonderful Life” Ediacara Hills of Australia Chengjiang beds of SW China Phylum- group of critters that share similar architecture, level of complexity and evolutionary history (phylon- tribe) ¾ 90% of all living animals are invertebrates ¾ 33 invertebrate phyla (show you 9) Phylum Porifera (Pons = holes, ferre – to bear)-aka {Sponge Bob} ¾ nearly all of the 10,000 species are marine ¾ Size: bean to a small car ⇒ Have spicules made of spongin (CaCO3, Si02) ¾ Widespread ¾ Shapes ⇒ Branching, vase-like, encrusting ¾ Suspension Feeders – strain plankton (400 gallons) ¾ No digestive system, no circulation, respiratory or nervous systems Phylum Cnidaria (old Coelenterata) ¾ 9000 species – jelly fish, sea anemones, corals ¾ cnidoblasts – stinging cells (Figure) (knide – nettle, blastikos – blast upward) ¾ Also have migratory cells which move nutrients around ¾ Cells 1. Gastrodermis – digestion and reproduction 2. Epidermis – protection and capture of prey ¾ ¾ ¾ ¾ Radial symmetry – body parts radiate from a central axis like spokes on a wheel No exeretory or circulatory system Primitive network of nerves Two forms (of body) 1. Medusae – jelly fish ¾ Biggest – cyanea – 12 ft bell, 59′ tentacles ¾ Sea Wasp – 50 ft tentacles can kill you in 3 minutes (Chironix) 2. Polyp – many footed ¾ Fixed typically ¾ Corals, sea anemones ¾ Corals – solitary – 12 inches diameter ¾ Colonial – ant sized – Hermatypic ¾ Zooxanthellac- dinoflagellates – symbiotic ¾ Prefer clear water ¾ Higher salinity – therefore, freshwater is deadly Worm Phyla ¾ Transition to more advanced ¾ Bilateral symmetry – left side, right side ¾ Have head with sensory tissue ¾ Some flow through digestive systems and excretory systems 1. Simplest – Platyhelminthes – flat worms Platys – flat Helmins- worm ¾ Parasites – tapeworms of vertebrates ¾ Most are free- living scavengers and predators ¾ Few are greater than 1 ¼ inches in length ¾ Most primitive with a central nervous system with brain and light sensitive eye spot ¾ Larger flatworms lack a true respiratory an excretory system ¾ Eliminate wastes by diffusion through cells (therefore, their body can be no more than a few cells thick) 2. ¾ ¾ ¾ Nematoda (Round worms) (nematos – thread) Flow through digestive tract (mouth, butt) Plentiful in almost all habitats Most of the 12 k species are free living Although some are parasitic (sushi) ¾ Plentiful 1 meter square by 4 cm thick=4,420,000 critters 3. Annelida Cannelus – ring ¾ Includes earthworm ¾ Advanced, segmented (Metamerism) ¾ Each segment can have its own nervous, muscular and repro tracts Class Polychaetae (chaetae – bristles) (Figure) – most important marine annelid ¾ 1-15 cm (1/2 to 6 inches) ¾ Feather duster- catches food ¾ Some are mobile, others in tubes ADVANCED INVERTEBRATES Phylum Mollusca (Molluscus – soft bodied) - Figure 15.10 ¾ Contains 80k (second to Arthropoda) ¾ Clams, snails, octopus, squid ¾ Most are marine and have a shell –internal -external ¾ Some species –acute eyesite, intelligence - octopus ¾ Probably came from a common ancestor of annelids ¾ Bilateral, heads, digestive tracts, nervous systems (a few are segmented) ¾ Structural diversity, can achieve great size 1. Gastropoda – Snails ¾ Abalone, conch, limpet, garden snail ¾ Grazers, suspension feeders, predators and a few are planktonic ¾ Beautiful shells – outside – shock absorber inside- smooth middle- CaC03 – strength ¾ Some do not have shells – Nudibranch (Figure) 2. Bivalvia – twin shells ¾ Clams, oysters, mussels ¾ Surrender mobility for protection, suspension feeders 3. Cephalopods (head foot- literal) ¾ Nautilus, Octopus, Squid ⇓ ⇓ ⇓ external none small one (shells) ¾ Squid and octopus more advanced ¾ Secrete an ink roughly their body size ¾ Squid – 59 feet long ¾ Squid – largest invertebrate ¾ Octopus- most intelligent – keen eyesight ¾ Only 450 species of cephalos now Phylum Arthropoda ¾ Arthron (joint) poda – foot ¾ Lobsters, shrimps, crabs, krill, barnacles ¾ Million of species ¾ Most successful phyla ¾ Krill-greatest biomass ¾ Variation of annelid – per or pairs of legs (or appendage) per segment ¾ All are bilaterally symmetric ¾ Do not have good nervous system, intelligence or eyesight ¾ But do have 3 major advances 1. Exoskeleton – form fitting external covering 2. Striated Muscle – Quick, strong, lightweight form of muscle that makes rapid movement and flight possible 3. Articulation – ability to bend appendages at specific points ¾ Exoskeleton – made of chitin (N rich carb) ¾ Molting – replacement of exoskeleton ¾ Largest class – insecta – all marines ones are water striders ¾ Crustacea – 30 k – primarily marine – gills ¾ Lobsters, crabs ¾ Bodies – 16 to 20 segments ¾ Big – King Crab – leg span of 12 feet ¾ Heaviest- lobster (48 lbs) feed 10 people ¾ Dominate oceans Phylum Echinodermata ¾ Echinos (hedgehog, skim) ¾ Lack eyes, brains ¾ 6000 species ¾ Radial symmetry (Pentamerous) ¾ Five classes 1. Asteroidea – sea stars – water vascular system 2. Ophiuroidea – Brittle stars – leave an arm 3. Echinoidea – sea urchins, sand dollars 4. Holothuroidea –sea cucumbers Figures 15.18-15.20 (15.18 - Sea Star, 15.19 – Water vascular, 15.20 – Brittle stars) PHYLUM CHORDATA ¾ Posess notochord ¾ 40k species ¾ about 5% lose notochord – invertebrate chordates 1. Invertebrate chordates (Figure 15.22) ¾ Tunicates – sea squirts ¾ Suspension feeders – look like sponges ¾ Amphioxus (sharp at both ends) ¾ Invertebrate with some vertebrate features 2. Vertebrate chordates a. Fish – possess gills, fins ¾ More than all other vertebrates combined ¾ Length – 0.4 inch to 60 feet ¾ Weight – 0.1g to 45 tons ¾ Speed – 75 mph (120 km/hr) ¾ Cold blooded – ectothermic ¾ 40% freshwater, 60% sea water ¾ 500 MYA first appeared, exploded 410 MYA ¾ Devonian Period (age of fish) – 408 –360 MYA 1. Class Agnatha – hagfish, lanpreys ↵ (Figure 15.25) ¾ Fewer than 50 species ¾ Slime to protect ¾ Lanpreys - parasitic 2. Class Chondrichthyes ¾ 280 MYA appeared ¾ sharks, slates, rays, chamaeras ¾ active ¾ cartilage skeleton ¾ sharks, rays – neg. buoyancy (no gas bladder) - (they’ll sink) ¾ diversity ¾ more people are killed by dogs each year than killed in the last century by sharks Sharks ¾ 80% of shark species are less than 2m long as adults ¾ Great White – 23 feet, 3000 lbs ¾ Mako- little one (13 feet) – attack small boats ¾ Largest – Whale Shark (60 feet, 90K pounds) 3. Class Osteichthyes ¾ 27K bony fish ¾ 90% are Teleostei (Perfect bone) (cod, tuna, halibut, perch) – Figure 15.29 ¾ 77 million tunas eaten ¾ Adaptations – camouflage, schools, speed, gas-filled swim bladders The problems of Fishes 1. Viscosity, Shape and Propulsion ¾ Small ones – difficult ¾ Streamlined-tuna (Figure 15.30) ¾ Eel like movement – not as efficient (Figure 15.31) ¾ Fastest 75 mph 2. Maintenance of level ¾ Cartilaginous Fish – swim constantly (no gas bladders) ¾ Gas bladders – swim bladders ¾ Fastest fish: no swim bladders 3. Gas Exchange ¾ Gill membrane take in dissolved 02 ¾ Active fish – bigger – gill area 4. Osmotic Considerations ¾ Osmoregulators ¾ Freshwater would gain water ¾ Saltwater would lose water 5. Feeding and Defense ¾ Lateral line system – defects low frequencies ¾ Cryptic coloration (camouflage) ¾ Turbot (Fig 15.34) ¾ schools ¾ Flying Fish Amphibians ¾ 2000 species exist – most are terrestrial Marine Reptiles ¾ Turtles, sea snakes, marine lizards, marine crocs ¾ Salt glands- excrete salts from body fluids Sea Turtles – 8 species of these ¾ Non retracting ¾ Figure 15.36 – Green one (Chelonia) ¾ Largest – Atlantic Leatherback (61/2 feet, 1300 lbs) ¾ Lay eggs on the beach they were hatched ¾ Ascension Island – studied there Marine Crocs ¾ Mangrove swamps, reefs ¾ 23 feet, over a ton Marine Birds 1. Tubenoses – Albatross (12 feet wing span, 22 lbs) (rarely flap- aerodynamic wings) 2. Pelicans – throat poaches, webbed feet ¾ Light delicate 3. Gulls including Terns 4. Penguins – only southern hemisphere MARINE MAMMALS ¾ Most advanced vertebrate group – 4300 species All marine mammals possess: 1. Streamlined Body Shape – with limbs adapted for swimming ¾ Drag is reduced by hair or slippery skin 2. Generate internal body heat –high metabolic rate ¾ No marine mammals are smaller than a sea otter (small ones would lose heat too fast) 3. Respiratory System is modified to collect and retain large quantities of 02 ¾ Empty lungs completely more easily ¾ Could hold breath longer and utilize 02 – whales 4. Osmotic Adaptations – skin is impervious to water ¾ Take in little water ¾ Excrete salty pee Three main Orders: 1. Cetacea – whales, dolphins, porpoise ¾ Thought to have evolved from hoofed land animals related to horse/sheep ¾ Range in size from 1.8m (6ft) to 33m (110 ft) weigh up to 110 tons ¾ Nostrils at top of head Suborders of Cetacea (Fig 15.39) 1. Odontoceti – toothed whales ¾ Include Orca, Dolphin, Porpoise ¾ High brain weight to body weight ratio ¾ Largest – Sperm Whale – 60 feet - dives deep (3740 ft) (can dive to 3740 feet) ¾ Search for food by echolocation (Fig 15.40) ¾ thought to use sound offensively as well ¾ Dolphins – 229 decibels ¾ Sperm Whales- 260 decibels 2. Mysticeti- baleen whales ¾ No teeth ¾ Eat krill (filter feed), and lots of it ¾ Feed close to the surface ¾ Blue Whale- largest – babies can grow at 9lbs per hour ¾ Social structure – Humpback, Bowhead 2. Order Carnivora a. Suborder Pinnipedia – wing foot – seals, sea lions, walrus ¾ Leave ocean to mate and raise young ¾ Appeared to have evolved from the same stock as modern bears 1. Seals – covered with short coarse hair without soft under fur, no ear flaps ¾ Rear appendages for swimming- not useful on land ¾ Diving record – 5120 feet – elephant seal 2. Sea Lions – have hind limbs with a greater range of motion (for use on land) ¾ Small ears, soft under fur ¾ Use front flippers for propulsion 3. Walruses – much larger ¾ 2 tons ¾ dig up clams with mouths ¾ use tusks for moving too b. Suborder Fissipedia (Split foot) (cats, dogs, coons, bears) 1. Sea Otters – smallest ¾ Densest and warmest fur ¾ Active & cute 2. Polar Bears – eat seals, beached whales ¾ Can swim 62 miles of open water ¾ 8ft tall, 1800 lbs 3. Order Sirenia ¾ Sirius -mermaid ¾ Dugongs and Manatees ¾ Herbivorous – (only ones) ¾ Graze on sea grasses, marine algae ¾ 10K world wide ¾ largest (15 feet, 1500 lbs)