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** Animals without a backbone or spinal column. Sponges & Cnidarians A. Characteristics: 1. Sessile = do not move 2. Asymmetrical 3. Filter feeders- sift food particles from water Phylum Porifera: “pore bearers”= Sponges!! Sponges & Cnidarians 4. Movement of water provides for feeding, respiration, circulation and excretion 5. Skeleton composed of spongin (soft) and spicules (hard). Sponges & Cnidarians A. Specialized Cells: 1. Choanocytes= collar cells– layer of cells with flagella keeps water moving; food vacuoles inside digest plankton (filter feeder). 2. Osculum- large opening at top of sponge; water exits. 3. Ostia- small openings at the side; water enters = pores! Phylum Cnidaria: Hydras, Jellyfish, Sea Anemone, Coral Sponges & Cnidarians A. What are they? 1. Soft bodied, carnivorous animals with stinging tentacles around their mouth. 2. Nematocysts- poison-filled, stinging structure that contains a coiled dart. Sponges & Cnidarians B. Form and Function 1. Body plan a) Polyp- usually sessile; mouth points upward b) Medusa- motile, bell-shaped body with mouth on bottom 2. Feeding- paralyze prey and pull it into gastrovascular cavity. (Gastro= feeding, Vascular= circulation) Sponges & Cnidarians C. Groups of Cnidarians 1. Jellyfish • Vary in size with the largest being almost 4 meters in diameter and tentacles more than 30 meters long; smallest is a few inches in diameter. • Australian box jelly: deadly to humans. • **Both polyp and medusa forms. Sponges & Cnidarians Australian Box Jellyfish The top prize for The World Most Venomous Animal would go to the Box Jellyfish. It has caused at least 5,567 recorded deaths since 1954. Their venom is among the most deadly in the world. It toxins attack the heart, nervous system, and skin cells. And the worst part of it is that jelly box venom is so overpoweringly painful, that human victims go in shock, drown or die of heart failure before even reaching shore. Survivors experience pain weeks after the contact with box jellies. Sponges & Cnidarians Irukandji jellyfish– world’s smallest!! The deadly Irukandji jellyfish is a tiny killer and can be unnoticed in the water. With bell and tentacles just 2.5 centimetres across, it is almost impossible to detect. A sting by the Irukandji jellyfish, on the other hand, is often felt as nothing more than a painful irritant with a rash akin to that of prickly heat. By the time more serious symptoms appear, it may be too late to save a life. Sponges & Cnidarians Lion’s Mane Jellyfish= World’s Largest! Although capable of attaining a bell diameter of 2.5 m (8 feet), these jellyfish can greatly vary in size, those found in lower latitudes are much smaller than their far northern counterparts with bells about 50 cm (20 inches) in diameter. The tentacles of larger specimens may trail as long as 30 m (90 feet) or more. These extremely sticky tentacles are grouped into eight clusters, each cluster containing over 100 tentacles,[5] arranged in a series of rows. At 120 feet in length, the largest known specimen was longer than a Blue Whale and is generally considered the longest known animal in the world.[6][7][8] Sponges & Cnidarians C. Groups of Cnidarians 2. Hydras and their relatives • Hydras have only polyp form • Texas coast– Portuguese man-ofwar has a polyp that forms a balloonlike float for the colony with stinging tentacles that can be meters long! Phylum Cnidaria Hydras and relatives Size: Float, 12 in (30 cm) long, 5 in (12.7 cm) wide; tentacles, up to 165 ft (50 m) long Size relative to a 6-ft (2-m) man: Sponges & Cnidarians C. Groups of Cnidarians 3. Sea Anemones and Corals • Sea anemones are individual polyps • Hard corals secrete skeleton of limestone and live as colonies for hundreds or thousands of years (many together create a coral reef) • Largest reef is the Great Barrier Reef in Australia- can be seen from space!! Phylum Cnidaria Sea Anemones and Corals Great Barrier Reef as seen from space Worms and Mollusks 1. Phylum Platyhelminthes = flatworms A. Form and function 1. Pharynx: muscular tube to suck in food (digestive) 2. Rely on diffusion for transport of oxygen and nutrients (because of flatness) (circulatory) 3. Flame cells: remove excess water from the body (excretory) Worms and Mollusks 4. Ganglia: group of nerve cells (no brain) (nervous system) 5. Eyespots: can detect changes in amount of light 6. Most reproduce sexually; are hermaphrodites– have both male and female reproductive organs Worms and Mollusks B. Groups 1.Turbellarians- flatworms (planarians) - Most live in marine or fresh water 2. Flukes- parasitic flatworms that infect internal organs of host • • Blood fluke Schistosoma lives in multiple hosts during life cycle (human and snail) Affects millions worldwide in areas that lack proper sewage systems Worms and Mollusks 1. Tapeworms • Adapted to life inside intestines of host; attach with scolex: head with suckers or hooks. Worms and Mollusks Phylum Nemotoda- unsegmented worms (roundworms) A. Roundworms and Human Diseases 1. Trichinella- reproduce in host and larvae burrow themselves into organs causing terrible pain. Worms and Mollusks 2. Filarial worms: (mostly in tropical regions of Asia) that live in the lymph vessels and cause elephantiasis, which causes extreme swelling. Worms and Mollusks 3. Ascarid worms– cause malnutrition in more than 1 billion people worldwide; absorbs digested food from humans, horses, cattle, dogs, pigs, chickens; humans get it from unclean vegetables not properly washed. Ascarid Worms Worms and Mollusks 4. Hookworms- ¼ of the people in the world are infected; eggs develop in soil and when unprotected foot comes into contact it uses sharp tooth like plates and hook to burrow into skin and eventually to intestines where they suck blood and cause weakness and poor growth. Worms and Mollusks Phylum Annelida- segmented worms (earthworms and leeches) A. Form and Function- have complex organ systems 1. crop- to store food and gizzard to grind it up 2. closed circulatory system- blood is contained within blood vessels 3. have a brain and nerve cords. Worms and Mollusks B. Groups 1. Earthworms- common in woods, gardens; aerate soil. 2. Leeches- external parasites that suck blood and body fluids of host; used medically to reduce swelling or for reattaching body parts; can suck up to 5 times its weight; secrete anesthetic so host does not know it’s there. Also, in its saliva is a fluid that prevents clotting of blood. Worms and Mollusks Phylum Mollusca- snails, slugs, clams, squid, octopus. A. Form and Function 1. snails and slugs feed with radula: tongue with hundreds of tiny teeth 2. siphon: tubelike structure where water enters and leaves the body 3. closed or open circulatory system (blood not always in vessels). Worms and Mollusks B. Groups 1. Gastropods- snails, slugs. Shell-less or single shelled that move with muscular foot on ventral side. 2. Bivalves- clams, oysters, mussels, scallops (have 2 shells) 3. Cephalopods- octopi, squid, nautilus. Head is attached to foot which may be divided into tentacles or arms. Arthropods and Echinoderms Phylum Arthrpoda- insects, crabs, centipedes and spiders. A. What are they? 1. segmented body; tough exoskeleton made of chitin 2. jointed appendages: structures such as legs or antennae that extend from the body. Arthropods and Echinoderms B. Form and Function 1. open circulatory system with well developed heart 2. well developed nervous system with brain– cephalization. 3. when they outgrow their skeleton, they molt: sheds exoskeleton and makes a new one. Arthropods and Echinoderms C. Groups 1. Crustaceans- crabs, shrimp, lobster, barnacles, pill bugs. *Two pairs of antennae, 2 or 3 body sections, and chewing mouthpieces called mandibles. Arthropods and Echinoderms 2. - Chelicerates- horseshoe crab, spiders, ticks, scorpions Chelicerae: fangs used to stab and paralyze (spider) Pedipalps: longer than chelicerae; used to grab prey (scorpion) Spiders don’t have jaws, so must liquefy food to swallow it. Ticks can transmit bacteria that cause Rocky Mountain Spotted Fever or Lyme disease Scorpion pedipalps are enlarged into claws; found in Southern US; venomous stinger kills or paralyzes prey and can chew their prey. Arthropods and Echinoderms 3. Uniramia- centipedes, millipedes - jaws, one pair of antennae, unbranched appendages - Centipedes- up to 100 pairs of legs; one pair of legs per segment; carnivorous with poisonous mouthparts. - Millipedes- two pairs of legs per segment; feed on dead plants Arthropods and Echinoderms 4. Insects- bees, ants, beetles, butterfly - Body divided into: head, thorax, abdomen - Three pairs of legs attached to thorax - Types of metamorphosis: - Incomplete: gradual change (immature form looks like adult) - Complete: dramatic change (immature form looks nothing like adult) - Some insect groups work as societies Indirect development Incomplete Direct development Complete Arthropods and Echinoderms Phylum Echinodermata- sea urchin, sea stars, sand dollars - Spiny skin, internal skeleton, water vascular system, suction cuplike structures called tube feet - Sea urchins help control distribution of algae - Sea stars are predators that control numbers of clams and corals - Crown of thorns is poisonous and feeds on coral.