Pelagic Marine Organisms/Adaptations
What are the different classes of fishes and general characteristic of each?
-Agnatha: Jawless Fish Lampreys, hagfish (most 'primitive' fish) -Osteichthyes: Bony fish, mostly of Order Teleost -Highly articulated skeleton -Flexible, easy to maneuver -Fast, sprinting motion -Chondrichthyes: Cartilaginous fish Sharks and rays Less articulated, less maneuverable Slow, gliding motion No swim bladder Most sharks bear live young (viviparous)
What was the first animal? Most abundant animal?
1st= ctenophore most abundant= arthropod-> krill
What types of organisms make up nekton? You should know major examples and defining characterisitcs given for given for each phylum discussed i.e. Arthropod, Cnidaria, Ctenophore, Mollusk, Chordates
ARTHROPODS "joint foot" Class: Meristoma - horeshoe crabs Class: Crusacea - shrimp, crabs, etc. -exoskeleton,3 body segments, jointed legs and appendages -large & diverse group with many zooplankton and benthos crabs, shrimps, krill, water fleas, barnacles etc. __Copepods probably found in every fresh or saltwater body Possibly the most abundant animal on Earth __Krill (euphausiids) are small, shrimp-like crustaceans dense masses called "swarms" or "clouds," that turn polar ocean's surface pink Possibly the most abundant animal on Earth Major diet of penguins, fishes, whales, squid and seals PHYLUM CNIDARIA (Coelenterates) Two basic body types (most have both during life cycle): Medusae - free floating stage (jellyfish-like..above) Polyp - attached to bottom (adult corals and anemones) Have stinging cells (nematocysts), carnivorous PHYLUM CTENOPHORES (Comb Jellies) Carnivorous Beat cilia to 'swim' No stingers, captures prey on sticky cells Phylum: CHORDATA (have a notocord: cartilaginous rod running underneath nerve cord) -Invertebrates e.g. tunicates (sea squirts) -Vertebrates (have spinal column) PHYLUM MOLLUSCA invertebrate Class Cephalopoda " head foot" -surrounded by tentacles Swimming by propulsion - squirt water from an interior cavity Carnivores - Catch prey with suction cup feet, kill with "beak" squid has: Two fins , A mantle , A head , 8 arms and two tentacles, each with hooks and/or suckers octopus has: mantle , head , 8 arms with one or two rows of suckers no tentacles
What caudal fin adaptations have been made for different fish 'lifestyles'?
ASPECT RATIO = (fin height)2 / fin area -gives information on caudal fin efficiency -Caudal fins provide the primary thrust for most fishes -Increasing the size of the caudal fin should increase speed but this also increases drag -High aspect ratios maximize thrust and minimum of drag for high cruising speed, but limits maneuverability -Low aspect ratio maximizes drag for the thrust: for high maneuverability with short bursts of speed (but low speed)
What are adaptations of marine organisms to deal with marine conditions of low light, cold temps (invertebrates versus mammals), high salinity, high pressures, staying afloat
DARKNESS (98% of ocean) -Large Eyes/light sensitivity -Bioluminescence (also Iridescence) Produced by symbiotic bacteria kept in cells Self-luminous cells: photophores Counter-illumination -Echolocation Mostly marine mammals: dolphins, whales Interpret echo returns and in terms of distance, size, texture and swimming direction of prey Make a rapid clicking noise with an specialized organ & sound received in lower jaw and transmitted to inner ear May use sound to stun or kill prey Volume: dolphins - 230 decibels, sperm whales - 260 d, military jets- 130 d -Electrosensing Ability of some fish to detect other organisms by sensing the weak electric field that surrounds them OR detecting disturbance in electric field emitted by the fish TEMPERATURE relatively constant Generally cold (2-3 degrees C) **Cold blooded (most) Internal temp = external temp Tend to move in short quick bursts Have special enzymes that operate at lower temperatures Fish: Heat generated by swimming muscles retained by specializations of the circulatory system Marine algae have special fats that remain liquid at low T (unsaturated..with double bonds e.g. omega-3 **Warm blooded - mammals (some fish) Stable, high internal temperature Advantage: Can move, eat, reproduce faster Insulating layer of fat (blubber) Dense layer of hollow fur traps a layer of air next to the skin Large size: Reduces surface area to volume ratio, less heat loss Controlling of blood circulation: Vasodilation controls where and when blood goes Countercurrent heat exchange in limbs allows cold blood returning to the body core from extremities to be warmed by exchanging heat with closely packed arteries going to the periphery. SALINITY Deep/open ocean withstand only a small salinity change (stenohaline) Many shallow-water coastal organisms can withstand changes in salinity (euryhaline) Diadromous Fish - migrate between FW and SW Problem is diffusion of ocean salts into body & osmosis of water out of body Tendency toward making distributions all equal..... - Be Isotonic: Keep bodily fluid the same salinity of seawater (most invertebrates) -Be Hypotonic: less salty than water drink a lot of water, secrete salt from special cells small volume of concentrated urine -Be Hypertonic: saltier than water Do not drink water Keep salts absorbed in special cells large volume of dilute urine HYDROSTATIC PPRESSURE Gradient in ocean = 1 atm/10 m 3-4 tons/square inch Problem for animals that migrate through the water column for food -Don't have rigid air pockets Have water-filled pockets so pressure inside = pressure outside -Diving marine mammals have no sinuses and compressible rib cage and lungs Another Problem: The 'bends' = nitrogen narcosis A diver descends while breathing air from tank Increase P = increase gas solubility so increase N2 in blood During quick ascent, the N2 becomes less soluble and forms bubbles in blood & bubbles can obstruct capillaries Solution: Collapse lungs so no air exchange while diving STAY AFLOAT Microplankton (Phyto & Zoo) - need to stay in sunlight so many contain a small drop of oil (less dense than water) to be buoyant use the viscosity of water: keep high surface area to volume ratio by being small and ornate (more so in less dense warmer water) Don't want to use energy swimming vertically - maintain neutral density -Many cephalopods (squid, nautoloids) have gas filled chambers -Giant Squid muscles contain weak ammonia (buoyant) solution -Some fish (weaker swimmers) have swim bladders (balloon-like organs) that can be filled or emptied by transfer of gas to and from blood or gulped from surface Can implode or explode with rapid depth change, so many predators have fat filled bladders
What types of organisms make up the zooplankton? (Know example zooplankton Ctenophore, Chordates, Cnidarians, Arthropod, Mollusks)
Holoplankton (permanent zoopl.) - Single-cellular organisms (Protists) - Many Arthropod: largest phylum of animals (include the insects, arachnids, crustaceans) Meroplankton (temporary zoopl.) - larvae and juveniles of a large range of organisms PHYLUM MOLLUSK - Pteropods (Sea Snails - Sea Butterflies) PHYLUM CHORDATE - Salps (planktonic tunicates) ARTHROPODS "joint foot" Class: Meristoma - horeshoe crabs Class: Crusacea - shrimp, crabs, etc. -exoskeleton,3 body segments, jointed legs and appendages -large & diverse group with many zooplankton and benthos crabs, shrimps, krill, water fleas, barnacles etc. Copepods probably found in every fresh or saltwater body Possibly the most abundant animal on Earth Krill (euphausiids) are small, shrimp-like crustaceans dense masses called "swarms" or "clouds," that turn polar ocean's surface pink Possibly the most abundant animal on Earth Major diet of penguins, fishes, whales, squid and seals PHYLUM CNIDARIA (Coelenterates) Two basic body types (most have both during life cycle): Medusae - free floating stage (jellyfish-like..above) Polyp - attached to bottom (adult corals and anemones) Have stinging cells (nematocysts), carnivorous PHYLUM CTENOPHORES (Comb Jellies) Carnivorous Beat cilia to 'swim' No stingers, captures prey on sticky cells Marine viruses
What is the general story of the evolution of fishes? And tetrapods from fishes?
Phylum: CHORDATA (have a notocord: cartilaginous rod running underneath nerve cord) -Invertebrates e.g. tunicates (sea squirts) -Vertebrates (have spinal column) New fossil species found in 375 m.y. Arctic Rocks Intermediate stage between fish and tetrapods with neck, jointed fins and scales higher vertebrates are basically 4-limbed air-breathing fish Why did they leave the ocean? Hypothesis: Vertebrates evolved in estuaries
What are the defining characteristics and major groups of marine mammals discussed in class?
Three orders contain marine mammals 1) Sirenia Manatee and dugong -The only herbivorous marine mammal -Slow moving, small brained -Subtropical -Closest marine relative to elephant -Near extinction (~10,000 individuals, Florida count 2001 = 3,276) -Loss of habitat, boats, red tide 2) Cetacean Whales, dolphin, porpoises 3) Carnivora Polar Bears Sea Otters Pinnipeds (seals, sea lions, walruses) - wing foot, evolved from bear group Seals (no ear flaps) Sea lions (with ear flaps) Sea otters: smallest marine mammal Most leave water to mate and raise young Elephant seal - deep diving record - 1.5 km Threatened, covered by 1972 Marine Mammals Protection Act
What are the differences between toothed and baleen whales and major members of each?
Toothed Whales: sperm whales, belugas, narwhales, killer whales, dolphins, porpoises -Single blowhole = nostril -Teeth -Active Predators, Intelligent? Social, communication -Echolocation -brain/body ratio (~0.016) matches that of archaic humans of ~2 mya Baleen Whales includes: grays, humpbacks, blues -Filter feeders -No echolocation -Baleen in place of teeth= fringed material, from roof of mouth, sieve to trap zooplankton
Why are many whales endangered?
Whales Nearing extinction ~ 1 million total (4.4 million in 1900) -Hunted by man for Food, oil, baleen for corsets, perfume -Now have a substitute for all uses -Whaling goes on for "scientific" purposes by Japan. The meat from this "research" is packaged and sold on the market. -Norway not bound by moratorim...hunts minke and fin whale (endangered, 2nd largest whale) -Iceland left the IWC in 1992 but rejoined in 2003 with a -reservation to the moratorium. It began commercial whaling in 2006.
