Transcript Polyps
Phyla of invertebrates include 1.Porifera 2.Cnidarian 3.Flatworms 4.Roundworms 5.Segmented worms 6.Mollusks 7.Arthropods 8.Echinoderms •Sessile animals that lack nerves or muscles. •However, individual cells can sense and react to changes in the environment. • • • • • Multicellular WITHOUT TISSUES Heterotrophic filter feeders No cephalization present Acoelomates Diploblastic-connected by noncellular mesogles Respiration: Occurs over the entire surface of the organism wherever cells are in direct contact with the environment. Aquatic, largely marine provide structural support and deter predators Body Plan •Most are asymmetrical •Harder sponges have spicules •Softer sponges have fibers made of a flexible protein called spongin. •Modified collagen :Choanocytes Sponge Spicules Spicules are the spiny skeleton of sponges –Secreted by specialized cells called Archaeocytes –Calcium Carbonate(CaCO4) or Glasslike Silica (SiO2) Feeding •Feed by drawing water into the body through many pores and extracting food particles. •Choanocytes-specalized cells with flagella. Choanocytes pass the food to the amoebocytes, which wander between the two cell layers. Reproduction Asexual: • New individuals bud from parents • Parent sponge breaks into many pieces (Fragmentation) Sexual: • Internal Fertilization • Male releases clouds of sperm into water, and water currents carry sperm to female • Some are hermaphrodites Larvae use flagella to swim to new location to become sessile adult Tentacles covered with nematocysts (stinging, harpoon-like structures that produce toxins that cause paralysis) Have nerve cells- nerve net- that can sense the environment. Unlike highly organized nervous systems, this nerve net transmits impulses in several directions at once, which results in multiple firings of nematocysts in parts not directly stimulated. Can detect light through structures called ocelli. Basic body plan-two variations: the sessile polyp and the floating medusa. • Polyps-adhere to the substratum by the aboral end and extend their tentacles, waiting for prey. • Medusas (also called jellies) are flattened, mouth-down versions of polyps that move by drifting passively and by contracting their bell-shaped bodies. Animation Digestion • Gastrodermis (cells that line the gastrovascular cavity) secretes digestive enzymes into the gastrovascular cavity. • Food particles then engulfed by cells. Sea Anemone Jellyfish Hydra Respiration: Occurs over the entire surface of the organism wherever cells are in direct contact with the environment. All Cnidarians have Cnidocytes • cnidocytes on the tentacles defend the animal or capture prey. • Organelles called cnidae evert a thread that can inject poison into the prey, or stick to or entangle the target. • Cnidae called nematocysts are stinging capsules. Feeding •Paralyzes the prey and then pulls it through its mouth into its gastrovascular cavity where digestion takes place. •Waste is excreted through the mouth. •Can also be filter feeders •Some live in symbiosis with autotrophic algae -Cassiopeia Cnidocytes: Stinging in Action • Specialized Stinging Cells called Cnidocytes which contain nematocyst in tentacles – When triggered by touch or chemicals; shoot harpoon like barb into victim – Also release toxin Reproduction and Life Cycle Have two life stages Sexes are generally separate Three types: 1) Medusa form dominates 2) Polyp form dominates 3) Solely polyp form Classes of Phylum Cnidaria •Scyphozoa- Jellyfish Medusa form dominates “Cup-Animal” •Class Hydrozoa •includes hydras and Portuguese manof-war (Physalia). a. The polyp stage is dominant. b. Portuguese man-of-war is a colony of polyps; original polyp is a gasfilled float. c. Other polyps specialize for feeding or reproduction. d. Can cause serious injury to swimmers with a tentacle having numerous nematocysts; each tentacle arises from the base of each feeding polyp. Obelia Portuguese man-of-war •Anthoaoz-Sea Anemones, corals Only a polyp stage “Flower-Animal” a. Sea anemones are solitary polyps 5-100 mm in height and 5-200 mm in diameter or larger. b. Many are brightly colored and resemble flowers. c. A thick, heavy body supports a mouth surrounded by hollow tentacles. d. Sea anemones feed on invertebrates and fish. e. They attach to rocks, timbers, etc., or may be mutualistic and attached to a hermit crab's shell. f. Corals may be solitary; most are colonial. g. Most live in shallow waters; accumulation of their calciumcarbonate remains builds reefs. Anthozoa Box Jelly fish In order for the Clownfish to live within the tentacles of the sea anemone, it must develop immunity to the stinging cells of the anemone. It does this by touching one or two tentacles at a time, over time the number of tentacles touched are numerous and eventually the fish creates mucus that protects it from the sting cells of that specific sea anemone. Once the clownfish does create a relationship with an anemone, it must stay with that specific anemone, because the stinging cells of individual sea anemones are different.