Lecture10MarineAnimalsI - Ch. 15 Marine Animals Marine •...

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Unformatted text preview: Ch. 15 Marine Animals Marine • Multicellular heterotrophic organisms • Obtain food (ultimately) from primary producers •Problems: Finding food Avoiding predators Finding mates (reproduction) • Use a variety of survival strategies Pelagic vs. Benthic Pelagic Like algae, animals may be “pelagic” or Like “benthic” (water column vs. bottom dweller) dweller) “Pelagic” = plankton or nekton Pelagic” (drifting/weak swimming vs. strong swimmers) swimmers) We will discuss all types Animals arose about 700-900 million years ago as Earth’s atmosphere became enriched in oxygen Animals grew in complexity as they became more abundant abundant (Dividing cells stuck (Dividing together after reproduction) together True animals evolved as True cells became specialized cells Fossils in Burgess Shale Fossils (Can), Ediacara Hills (Aus), Chengjiang beds (China) Chengjiang Were buried on continental Were shelves, probably by turbidity currents turbidity Marine worm fossil, about 530 million years old Trilobite, once common in the ocean but now extinct (500 million years old) The Invertebrates The More than 90% of living and fossil animals More are “invertebrates” are Soft-bodied animals that lack a rigid Soft-bodied internal skeleton internal Often have a hard protective outer Often covering covering Comprised of many different, diverse Comprised phyla (worms to squid) phyla Phylum Porifera Phylum “Porus” = holes, “ferre” = to bear Includes the sponges Includes Most primitive of the true animals Most 10,000 species (nearly all marine), distributed from inter-tidal to abyssal zone, all latitudes all branching, vase-like, encrusting branching, No digestive system Sponges are suspension feeders; strain plankton and detritus from water that enters through pores; swept out by collar cells Phylum Cnidaria Phylum Includes jellyfish, sea anemones, and corals About 9,000 marine species Name comes from cnidoblasts, or stinging cells Name cnidoblasts or (nematocysts) used to immobilize prey (nematocysts) Prey = large zooplankton, small fish Sac-like digestive cavity; digested food is Sac-like absorbed by cells and transported by migratory cells and diffusion cells Only one body opening; wastes eliminated orally Cnidoblast, characteristic of cnidarians; used to stab, poison prey Sea wasp (Chironix); tropical jellyfish, 15 m long tentacles, can kill a human in 3 minutes Cnidarians, con’t Cnidarians, Radial symmetry Two forms: medusae and polyps Two medusae Jellyfish are medusae, swim by rhythmic swim contraction of their bells; catch prey with tentacles (cnidoblasts) tentacles Sea anemones and corals are polyps; sedentary, attached to substrate sedentary, Corals have a calcareous skeleton Corals covered by living tissue; usually colonial covered Hermatypic Corals Hermatypic Are tropical, reef-building corals Are tropical, Hermatos = “mound building” Contain masses of zooxanthellae Contain (photosynthetic dinoflagellates); provide 98% of the coral’s nutrition the Require light; max z= ~150 m coral provides nutrients and protection zooxanthellae eliminate waste (nutrients & CO2), keep pH alkaline and supplement growth Global Distribution of Coral Reefs Coral Reefs Coral Have the greatest known species diversity in the marine environment Have 25% of all known marine species Require warm waters (restricted to the tropics, >18° C) Live in oligotrophic waters (low nutrient concentrations) in clear waters free from suspended particulates Found in relatively shallow waters (most coral species require light) Must grow on a firm substrate Coral Reefs Many species produce unique compounds with medicinal properties (anti-cancer, anti-tumor, anti-inflammatory, sunscreens, etc.); Antipredator compounds? Coral Reefs are threatened worldwide by: Human Activity - fishing, anchors, eutrophication, collisions Global Climate Change - El Niño and coral bleaching Biological Factors - disease, algal overgrowth, Crown of Thorns starfish grazing (eat coral polyps) Coral bleaching Physical Factors - storms, erosion Coral Reef Bleaching Coral Worms Worms (Phyla: Platyhelminthes, Phyla: Nematoda, and Annelida) Nematoda, Includes, flatworms, roundworms, Includes, segmented worms segmented These phyla represent transition to more These advanced organisms advanced Bilateral symmetry Have sensory tissue in a “head”, flowthrough digestive systems, circulatory through systems for fluids and waste systems Intertidal flatworm (Platyhelminthes) Marine polychaetes (Annelida) Polychaetes in burrow Phylum Platyhelminthes Phylum Primitive; but have a central nervous Primitive; system (nerve cells connected to a pair of simple eyespots) simple Parasitic or free-living Parasitic Scavengers, on rocks or in burrows Large flatworms are thin; allows for Large diffusion of gases & wastes; lack true excretory systems excretory Phylum Nematoda Phylum First phyla to contain a flow-through First digestive system (mouth and anus) digestive = roundworms 12,000 known species; ubiquitous Free-living (sediments) or parasitic (in Free-living vertebrates and invertebrates) vertebrates Sushi lovers beware (Anisakis) Phylum Annelida Phylum Segmented worms (rings or segments) Class Polychaeta is largest and most diverse Class class class Often brightly colored or iridescent with bristly Often projections from each segment projections Short (1 cm) to long (15 cm) in length Important “bioturbators”; burrow and devour Important sediment sediment May also form tubes, fixed in place, then hoover May sediment for food sediment ...
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This note was uploaded on 02/22/2012 for the course MSCI 102 taught by Professor Benner during the Spring '10 term at South Carolina.

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