Marine Organisms Inverts Friday May 1 2015 3 16 PM Invertebrates A Animal Characteristics Eukaryotic cells Lack cell wall Heterotrophs do not produce their own food Multicellular Motile at some stage All above sponges have muscle and nervous tissue B Animal Classification Millions of spp Grouped according to similarities Most similarities reflect evolutionary history Basis for grouping includes Tissues Symmetry Body cavity Segmentation Cephalization Inverts C D Vertebrates C Survey of Marine Inverts Phyla Porifera sponges Cnidarians jellyfish coral hydroids Ctenophores comb jellies Nemertea ribbon worms Nematoda roundworms Mollusca snails bivalves squid Annelida segmented worms Arthropods crustaceans Echinodermata starfish sand dollars urchins D Porifera sponges Characteristics Structure Body form Feeding Reproduction Ecological role E Characteristics a convenient way of surveying marine animals is based on the presence of a vertebral column F Structure Shape and size determined by substrate and water currents Sessile attached to bottom Lack symmetry Lack tissues several specialized cells Suspension feeders filter food from water Many drab some brightly colored Wide variety of shapes and sizes Built around system of water canals Water in through tiny pores ostia Water out through large opening osculum Water brings in oxygen and nutrients Outgoing water takes wastes out Lack tissues but have specialized cells Collar cells choanocytes Flagellated Beating creates water current Pinacocytes Amoeba like cells Layer of cells that form outer covering Move within sponge Transport food Repair can form any type of sponge cell Spicules CaCO3 or SiO2 Support body Matrix of flexible protein G Body form Size limited by ability to circulate water Evolution folding of body wall allowed increased water flow and larger size Types of sponges Asconoid Simplest body form Tubular always small Found in clusters Leuconoid Highest degree of folding Many chambers lined with choanocytes Most sponge spp this type H Feeding Filter feeders Beating of flagella creates currents drawing water through ostia and out osculum Eat bacteria plankton detritus Few animals can capture food as small as food of sponges Utilize untapped food resources not available to others Accounts for success of sponges e Reproduction Fragmentation Budding New sponge from pieces broken off Cells on outer surface develop into small new sponge Drops off and forms new individual Most hermaphroditic both male and female gametes fertilization in water Asexual Sexual f Ecological role Competition for space with bryozoans and corals Symbiosis many have cyanobacteria Predator prey Few animals eat sponges Some fish mollusks hawksbill turtle Nutrient cycling Ca 2 Cnidarians jellyfish coral hydroids a What are cnidarians b Body forms c Tissue organization d Stinging cells e Classification f g Reproduction h Ecological role Feeding 3 What are cnidarians Jellyfish coral anemone hydra a b Simple design but wide array c Radial symmetry d Two tissue types e Gelatinous layer f Gastrovascular cavity surrounded by tentacles g Tentacle with stinging cells nematocysts Body forms Polyp Benthic Cylindrical body with opening at one end Mouth surrounded by tentacles Medusa Free floating jellyfish Many exhibit both life stages Some only in polyp stage coral anemone c Tissue organization a Radial symmetry body parts arranged in circular patterns around central axis b Two life stages Outer layer of cells epidermis Large body cavity gastrovascular cavity Lined with layer of cells gastrodermis Between cell layers is gelatinous material mesoglea forms most of animal s body Two tissue layers during development higher animals all have 3 layers Muscle and nervous tissue d Stinging cells Contain stinging organelle cnida Over 20 types of cnidae Most nidae are spreading type called nematocysts Cnidocil trigger when touched discharges nematocyst also triggered from chemicals from some prey Some have thread that tangles prey Once fired cell reabsorbed and replaced by new cell Stinging cells most common on tentacles Cause intense pain paralysis usually not fatal to humans unless allergic to toxin Box jellies can kill a person in minutes Leatherback turtles not bothered by nematocysts feed heavily on jellyfish Some nudibranchs ingest jellyfish and incorporate nematocysts into skin and use them for their own protection e Classification Three classes Hydroids siphonophores Portuguese Man of War Hydrozoans Scyphozoans Jellyfish Anthozoans Coral sea fans anemones Colonial or solitary f Hydrozoans Mostly colonial Colonial hydrozoans usually have two polyps Feeding polyps capture food Reproductive polyps produce gametes Medusa usually small Some floating colonies g Scyphozoans True jellyfish Both polyp and medusa but medusa dominant Some 7 10 ft diameter 200 foot long tentacles Best known is Portuguese Man of War Colony suspended from gas float Contains several types of polyps fishing polyps with long stinging tentacles Continuously swim up Photoreceptors sense light vertically migrate Swim both vertically and horizontally 3 Anthozoans Sea anemones corals soft corals Benthic all sessile adults Many form large colonies Only polyp stage Coral Polyps secrete skeleton Hard coral Scleractinian corals CaCO3 Large colonies connected by horizontal sheet of tissue Soft corals sea fans sea pens sea feathers Colonies that resemble plants Octocorals 8 tentacles Digest prey in gastrovascular cavity Many hydrozoans anthozoans are filter feeders Others carnivorous fishes large invertebrates Paralyze prey with toxin Draw prey through mouth to gastrovascular cavity Feeding f g Reproduction Asexual Sexual Usually in polyp stage Budding tiny medusa like buds released by polyps into water Usually medusa stage Medusa hermaphroditic or separate sexes Release gametes fertilization formation of planula larva disperse and settle and form polyp stage Coral among most ecologically important animals in any marine environment Feeds on many animals not fed on by many h Ecological role Predator prey Habitat Symbiotic relationships Coral zooxanthellae Anemone clownfish shrimp 3 Ctenophora combjellies 100 spp all marine Mostly planktonic radial symmetry gelatinous body Many bioluminescent Digestive system mouth and anal pores Rows of fused cilia combs locomotion Long sticky tentacles food nets for food capture Draws food from tentacles to mouth or to rows of cilia and then to mouth Especially good at capturing