Objectives. Chapter 8. Objectives. I. What Are Animals? II. Sponges. Marine Phyla

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1 Objectives Chapter 8 Sponges, Cnidarians, Comb Jellies, and Marine Worms Describe the structure and function of sponge biology. Understand the role sponges play in ecoystems. Differentiate between Cnidarians and ctenophores Describe how cnidarians capture food items and protect themselves from predators. Objectives Describe the structure of marine worms. Define and give examples of meiofauna. Describe the body structure of polychaetes and explain how their form relates to their function. I. What Are Animals? Animal characteristics: 1. multicellular distinguishes them from bacteria and most protists 2. eukaryotic cells without cell walls distinguishes them from bacteria, fungi, algae and plants 3. heterotrophs 4. motile - (with the exception of adult sponges) Marine Phyla II. Sponges 1. Porifera -sponges 2. Cnidaria corals, anemones, jellies 3. Ctenophores comb jellies 4. Platyhelminthes flatworms, turbellaria 5. Nematoda round worms 6. Mollusca snails, clams, squid, octopus 7. Annelida sea worm, tube worm 8. Arthropoda lobster, crab and krill 9. Echinodermata sea stars, sea urchins, sea cucumber 10. Chordates tunicates, salps, fish, reptiles, birds, & marine mammals Phylum Porifera Basic characteristics: simple asymmetric sessile permanently attached to a solid surface have many shapes, sizes and colors approximately 5,000 species of sponges

2 II. Sponges Hexactinellida Phylum Porifera Basic characteristics: three distinct groups: Hexactinellida (glass sponges) Demospongia Calcarea(calcareous sponges). Demospongia Calcarea www8.nos.noaa.gov ( Jeffrey L. Rotman/Corbis. Reproduced by permission.) Sponge Structure and Body is built around a system of water canals ostia tiny holes or pores through which water enters the sponge s body spongocoel spacious cavity in the sponge osculum large opening through which water exits from the spongocoel

3 Sponge Structure and Lacking tissues, sponges have specialized cells collar cells (choanocytes) use their flagella to provide force for moving water through the sponge s body pinacocytes provide an outer covering for the sponge archaeocytes cells that resemble amoebas, and can move through the body can assume any of the other cell forms, or transport materials Sponge Structure and Structural materials spicules skeletal elements that give support to a sponge s body, which are produced by specialized cells and composed of calcium carbonate, silica or spongin spongin a protein that forms flexible fibers Sponge Structure and Sponge size and body form Size limited by water circulation Body Form asconoid simplest form; tubular and always small syconoid some folding of body-wall leuconoid many-chambered sponges with the highest degree of folding Sponge Structure and Nutrition and digestion filter feeders sponges are one of the few animals that can capture particles 0.1 to 1.0 micrometers in size Sponge Structure and Reproduction in sponges asexual reproduction budding a group of cells on the outer surface of the sponge develops and grows into a tiny new sponge, which drops off fragmentation production of a new sponge from pieces that are broken off sexual reproduction eggs usually develop from archaeocytes and sperm from modified collar cells larval stage is a planktonic

4 Ecological Roles of Sponges Competition compete for space to attach with corals and bryozoans Predator-prey relationships few species eat sponges spicules are like needles some produce chemical deterrents *major food source for hawksbill sea turtles Ecological Roles of Sponges Symbiotic relationships sponges are mutualistic or commensalistic hosts to many organisms e.g. mutualistic bacteria many organisms live within the canals or spongocoel, for protection, water flow Ecological Roles of Sponges Sponges and nutrient cycling boring sponges recycle calcium as they burrow into coral and mollusc shells Sponges of New England Finger Sponge (Haliclona oculata) Short stalk with flat to rounded fingershaped branches. Light brown, graybrown, or purple in color. Found attached to rock habitat from low tide line to 400'. Grows to 18" high. Red Beard Sponge (Microciona prolifera) - Short branching sponge with flattened branches. Differs from Finger Sponge in color orange to red. Found on rock, pilings and other solid substrate. Grows up to 8" high. Bread Sponge (Halichondria parma) - Subtidal depths. Encrusting sponge found on rock, pilings, etc. Colors vary from brown, orange, yellow and green. Occurs in many shapes, but normally has cone-shaped bulges. Can grow to several feet in diameter. Can be difficult to identify. Intertidal to 200'. Common Palmate Sponge (Isodictya palmata) - Sponge with more flattened than rounded branches. Holes (oscula) in sponge are very obvious - more so than any other branching sponge in the region. Grows to 12" high. Color yellow, brown to orange. Found sub-tidally.

5 II. Cnidarians: Animals with Stinging Cells Phylum Cnidaria Named for their cnidocytes stinging cells Cnidocytes are used to capture prey and protect the animal A. Organization 1. Radial symmetry 2. Often exhibit 2 body plans within their life cycles: a. polyp a benthic form characterized by a cylindrical body with an opening at 1 end b. medusa a free-floating stage (jellyfish) B. Stinging Cells 1. Cnida stinging organelle within a cnidocyte Used for prey capture & defense nematocysts are discharged

6 B. Stinging Cells 2. Dangerous species (Physalia physalis) Portuguese man-ofwar (painful stings) (Chironex Fleckeri) box jellyfish (can kill within 3-20 minutes) C. Types of Cnidarians 1. Hydrozoans (class Hydrozoa) a. mostly colonial b. colonial forms contain 2 types of polyp: feeding polyp functions in food capture reproductive polyp specialized for reproduction c. hydrocorals secrete a calcareous skeleton e.g. (millepora sp.) fire coral d. some produce floating colonies e.g. (physalia physalis) Portuguese man-of-war

7 Types of Cnidarians 2. Class Scyphozoa a. true jellyfish medusa is predominant life stage photoreceptors sense organs that can determine whether it is dark or light e.g. (aurelia aurita) moon jelly 3. Class Cubozoa tropical voracious predators, primarily of fish e.g. (Chironex fleckeri ) australian sea wasp Types of Cnidarians 4. Class Anthozoa a. sea anemones polyps with a vascular cavity divided into compartments radiating from the central one though sessile, many can change locations

8 Types of Cnidarians Anthozoans continued b. coral animals polyps that secrete a hard or soft skeleton form reefs along with types of algae Types of Cnidarians Anthozoans continued b. soft corals polyps that form plant-like colonies Ptilosarcus gurneyi

9 D. Nutrition and Digestion 1. Gastrovascular cavity central cavity where cnidarians digest their prey 2. Many hydrozoans and anthozoans are suspension feeders 3. Some jellies and box jellies eat fish and larger invertebrates 4. Sea anemones generally feed on invertebrates E. Reproduction 1. Hydrozoans generally exhibit asexual polyp stage and sexual medusa stage in the life cycle reproductive polyps form medusa-like buds which grow into adults after release adults release gametes into the water, where they are fertilized and form larvae planula larva planktonic larva that grows in the water column, then settles E. Reproduction 2. Scyphozoans medusae (sexual stage) release gametes into the water for fertilization planula larvae settle, grow into polyps, and reproduce medusa-like buds asexually

10 E. Reproduction 3. Anthozoans asexual reproduction pedal laceration leaving parts of the pedal disk (base) behind to grow into new animals fission the anemone splits in two and each half grows into a new individual budding produces large colonies of identical hard corals sexual reproduction larval stage is a planula larva F. Ecological Relationships of Cnidarians 1. Predator-prey relationships cnidarians are predators stinging cells discourage predation 2. Habitat formation coral polyps form complex 3-dimensional structures inhabited by thousands of other organisms coral reefs provide a solid surface for attachment, and buffer waves and storms F. Ecological Relationships of Cnidarians 3. Symbiotic relationships Portuguese man-of-war and man-of-war fish reef-forming corals and zooxanthellae sea anemones... and clownfish and the hermit crab Ctenophores Phylum Ctenophora Planktonic, nearly transparent Ctenophore structure named for 8 rows of comb plates (ctenes) which the animal uses for locomotion ctenes are composed of large cilia exhibit radial symmetry bioluminescent

11 Beroe spp. Pleurobrachia spp. Ctenophores oceanexplorer.noaa.gov d.wrobel Digestion and nutrition carnivorous, feeding on other planktonic animals may used branched tentacles in a net pattern, adhesive cells, jellyfish stingers Ctenophores Reproduction almost all are hermaphroditic fertilization may be in the water column, or eggs may be brooded in the body cydippid larva free-swimming larva resembling the adult ctenophore