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CHAPTER 26 Sponges, Cnidarians, Flatworms, and Roundworms Phylum Porifera (Sponges) Characteristics: Simple body structure with no true tissues; multicellular, (hermaphrodites—animal has both male and female structures), asymmetrical Sessile—no movement as adults; are filter feeders (catch food as it floats through them) Have pores that absorb water Spicules—tiny hard particles of calcium or silicon compounds that make up skeleton Phylum Porifera (Sponges) Reproduction: can be asexual (budding) or sexual by releasing sperm that enters other sponges through pores where it will fertilize the egg. After fertilization, larvae will develop. Larvae are immature stages of an animal. Sponge Reproduction Sperm cells Egg cell Flagella Larvae New sponge Sponges Review Questions 1. What word means that a sponge does not move? Sessile 2. How do sponges eat? By filtering the water around them 3. What tiny, hard particles make up the sponge skeleton? Spicules Phylum Cnidaria and Cnetophora Mouth Characteristics Tentacle Radial symmetry with true tissues; cup/bell shaped Have stinging cells called Cavity Inner cell nematocysts to help capture layer food Jellylike Bud Sting can be fatal to humans layer examples: hydra (very tiny Outer cell Disc layer jellyfish-like animal), Has one body opening made of two jellyfish, coral, sea layers of cells anemones Body Form of Cnidarians Has 2 life forms during their life cycle: Polyp- has a tube-shaped body with a mouth surrounded by tentacles. Medusa- has an umbrella-shaped body called a bell. Polyp Medusa Reproduction in Cnidarians Reproduction: Sexually and asexually through budding Review Questions 1. What type of symmetry do cnidarians have? Radial 2. What are nematocysts? Stinging cells 3. Give an example of a cnidarian. Coral, jellyfish, sea anemone, hydra 4. What are the 2 life forms of a cnidarian? Polyp & medusa Phylum Platyhelminthes “Flatworms” Characteristics Simplest animal with bilateral symmetry; have long, thin flat bodies. Usually hermaphroditic. Many are parasitic (ex: tapeworms, liver flukes) Phylum Platyhelminthes “Flatworms” Reproduction Usually hermaphroditic and reproduce sexually. During mating, they fertilize each other at the same time. Some can reproduce asexually by regenerating (regrowing) lost parts. (ex: cut planarian: will grow back lost parts!) Flatworms Life Cycle of a Flatworm Adult flukes Embryos released Larva Human host Snail host Larva Phylum Nematoda “Roundworms” and Rotifera Characteristics Bilateral symmetry, have both mouth and anus Live in soil, fresh and marine water. Nematodes: roundworms that are often parasitic Examples: Ascaria (intestinal roundworm about 1 ft long), hookworms, trichinella (from undercooked pork), pinworms, heartworms Phylum Nematoda “Roundworms” and Rotifera Reproduction Most have separate sexes. Lay eggs. FYI: Roundworm parasites of humans Hookworm infections are common in humans in warm climates where they walk on contaminated soil in bare feet. Hookworms cause people to feel weak and tired due to blood loss. FYI: Roundworm parasites of humans Pinworms are the most common human roundworm parasites in the United States. Pinworms are highly contagious because eggs can survive for up to two weeks on surfaces. FYI: Ascaris Eggs of Ascaris are found in soil and enter a human’s body through the mouth. Ascaris worm coming out of a pig. Beard worm Christmas tree worm - Also have: (turn to pink sheet) Setae—external Phylum: ANNELIDA “Segmented worms” movement Coelom—true fluid-filled body cavity Description: (PG.16 Purple Sheet) Bilateral symmetry, segmented body, closed circulation (have vessels) and true digestive system, oxygen diffuses through skin bristles for Ex: Earthworms, leeches Earthworms loosen soil and make it better for growing plants Reproduction Sexual: hermaphrodites (have sperm and eggs), cannot fertilize themselves. Earthworm Phylum: ANNELIDA “Segmented worms” Leeches CHARACTERISTICS: Body Temp - Ectothermic Symmetry - Bilateral Digestive System – Complete Skeletal System – None Circulatory System – Closed Reproductive System – Sexual Heart Chambers – Heart Body Mollusks • Class Gastropoda (snails & slugs)…2nd largest class after Class Insecta • Class Bivalvia “Bivalves” (scallops, oysters, clams, mussels) • Class Cephalopoda (squid & octupi)…Only mollusks with brains! Phylum: MOLLUSCA *from Latin word, “molluscus” - soft Description: *2ND Largest Phylum of Animals 3 Main Body Parts: 1. Muscular foot 2. Head 3. Visceral mass (its insides) FYI: terrestrial and marine Giant clam Sea Slug Reproduction Sexual: most have separate sexes, produce gametes CHARACTERISTICS: Squid Ectothermic Symmetry - Bilateral Digestive System – Complete Skeletal System – None Circulatory System – *OPEN* Reproductive System – Sexual Nervous System - Simple Heart Chambers - 2 or 3 in some Phylum: MOLLUSCA Nautilus octopus o Subphylum Crustacea (lobsters, crabs, crayfish…GILLS) o Class Insecta (all insects have 6 legs) o Class Arachnida (spiders & scorpions…all have 8 legs) o Class Diplopoda (millipedes) o Class Chilopoda (centipedes) Arthropods Crabs Phylum: ARTHROPODA “Arthropods” Bull Ant Description: • Have segmented appendages (joints) that allow for flexibility •Molting—since exoskeletons do not grow, arthropods have to shed exoskeleton and form new one Crabs Phylum: ARTHROPODA “Arthropods” Bull Ant Description: • Mandibles—mouthparts for holding, chewing, sucking, biting •Have segments fused into three main body sections: head, thorax, abdomen; a fusion of the head & thorax = cephalothorax - Oxygen obtained through: gills, tracheal tubes, or lungs Metamorphosis—series of 4 changes in shape and body structure during development. Incomplete metamorphosis— only has 3 stages; once such an insect hatches, it looks almost like the adult version and is called a nymph • Many have camouflage to blend in with surroundings Locust molting “Evil” Butterflies Lobster CHARACTERISTICS: Body Temp - Ectothermic Symmetry - Bilateral Digestive System – Complete Skeletal System – Exoskeleton Circulatory System – Open Reproductive System – Very diverse Nervous System - Simple Heart Chambers – Muscular Tube A termite mound made by the cathedral termite The Arachnids: Ticks & Mites Tick American House Mites Spiny Cushion Sea Star Description: Move with tube feet— appendages with suction cups on tips FYI: Have mouth, stomach, intestines, but no head/brain All echinoderms have exoskeletons made of calcium carbonate. Feather Star Egyptian Sea Star Sand Dollars Reproduction Sexually with gametes, asexually with regeneration CHARACTERISTICS: Phylum: Echinodermata “Echinoderms” Body Temp - Ectothermic Symmetry - Radial Digestive System – Complete Skeletal System – Exoskeleton Circulatory System – Open Reproductive System – Sexual & asexual Heart Chambers – No true heart