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Mollusks, Arthropods, and Echinoderms Table of Contents Mollusks Arthropods Insects Insect Ecology Echinoderms Mollusks, Arthropods, and Echinoderms The Animal Kingdom Chapter 2: Mollusks, Arthropods and Echinoderms Mollusks, Arthropods, and Echinoderms Phylum Mollusca: Snails, Clams, Squid • Characteristics: – All have soft bodies and bilateral symmetry. – The Latin word, “mollis” means “soft”. – Most secret hard, calcium carbonate shells to protect themselves. Mollusks, Arthropods, and Echinoderms - Mollusks • Although they don’t look much alike at first, a snail, a clam, and a squid have the same basic body structures. Mollusks, Arthropods, and Echinoderms • Basic body pattern of most mollusks: 1. Head: containing the mouth 2. Muscular foot: for crawling, digging, or swimming. 3. Mantle: a thin layer of tissue that surrounds the main body organs. The mantle secretes the shell. 4. Gills: used to breath oxygen from water. Mollusks, Arthropods, and Echinoderms • Classes of mollusks include: 1. Gastropoda (stomach-foot) —snails, slugs, and sea slugs. *One shell (univalve) *Live in the water or on land *Make beautiful sea shells Mollusks, Arthropods, and Echinoderms *Use a flexible ribbon of tiny teeth called a radula to get food. *Some are herbivores *Some are carnivores Mouth Radula Radula Teeth Mollusks, Arthropods, and Echinoderms 2. Bivalvia (two-shells)-- clams, oysters, scallops and mussels. *Filter feeders—most are omnivores *Economically important as food *Used in production of pearls. Mollusks, Arthropods, and Echinoderms - Mollusks • A razor clam digs into the mud by changing the shape of its foot. Mollusks, Arthropods, and Echinoderms 3. Cephalopoda (head-foot) —octopus, squid, cuttlefish, and chambered nautilus. *Muscular foot is divided into tentacles for swimming. *Complex and intelligent. *Range in size from 1-60 feet. *Carnivores *Crawl or swim by jet propulsion Mollusks, Arthropods, and Echinoderms Not all cephalopods have a shell Octopus—no shell Squid—internal shell Chambered Nautilus external shell Mollusks, Arthropods, and Echinoderms Cool Videos!! Never underestimate the skills of the octopus! Octopus Escape Video (45 sec) Octopus Killing Shark Video (2 min 01 sec) Mollusks, Arthropods, and Echinoderms Phylum Arthropoda: Jointed Legs • Characteristics: – Largest group of animals with over 1 million species known. That number may be as high as 10 million. Mollusks, Arthropods, and Echinoderms – Exoskeleton made of chitin. Must be shed from time to time in a process called molting. – Segmented bodies – All have jointed appendages (legs, antenna, pinchers and claws) – Open circulatory system – Bilateral symmetry – One-way digestive tract Mollusks, Arthropods, and Echinoderms • Five classes: Arachnida, Crustacea, Chilopoda, Diplopoda, Insecta Mollusks, Arthropods, and Echinoderms 1. Crustaceans: crabs, lobsters, crayfish, shrimp and pill bugs. *Most have two body regions: cephalothorax and abdomen. *Five pairs of appendages including large pinchers on most. *Most have two pair of antenna Mollusks, Arthropods, and Echinoderms Fiddler crab Pill Bug Crayfish Mollusks, Arthropods, and Echinoderms 2. Arachnids: spiders, scorpions, mites and ticks. *Most have two body regions: abdomen cephalothorax. *simple eyes *poison glands, fangs or stingers *four pair of legs Mollusks, Arthropods, and Echinoderms Spiders are found everywhere. They spin webs using spinnerets in their abdomen. Mollusks, Arthropods, and Echinoderms Scorpions are found in tropical areas and hunt insects and spiders. Mollusks, Arthropods, and Echinoderms –Ticks are external parasites that feed on the blood of a host. Some transmit Lyme Disease and Rocky Mountain Spotted Fever. –Mites are usually found in dust and are mostly harmless. Mollusks, Arthropods, and Echinoderms 3. Chilopoda: centipedes *Long, flat bodies with one pair of legs per body segment. *Carnivores: eat snails, slugs and worms and can bite humans. Mollusks, Arthropods, and Echinoderms 4. Diplopoda: millipedes –Long, rounded bodies with two pairs of legs per body segment. –Plant eaters: will not bite humans Mollusks, Arthropods, and Echinoderms 5. Insects: largest group of arthropods – Three body segments: head, thorax and abdomen. – Three pairs of legs attached to the thorax. – One pair of antenna. – Some have one or two pairs of wings; some have no wings. – Large, compound eyes; some also have simple eyes. – Open circulatory system. Mollusks, Arthropods, and Echinoderms Wings Abdomen Antenna Thorax Head Compound Eyes 3 Pair of Legs Mollusks, Arthropods, and Echinoderms - Arthropods Links on Arthropods • Click the SciLinks button for links on arthropods. Mollusks, Arthropods, and Echinoderms –All insects undergo metamorphosis *This is a process in which an animal’s body undergoes dramatic changes in its life cycle. *Two types of metamorphosis: Complete and Gradual Mollusks, Arthropods, and Echinoderms -Stages of Complete Metamorphosis: *Egg, Larva, Pupa, Adult (Beetles, bees, butterflies, flies and ants use complete metamorphosis) Mollusks, Arthropods, and Echinoderms - Insects Life Cycle • An insect with complete metamorphosis has four different stages: egg, larva, pupa, and adult. Mollusks, Arthropods, and Echinoderms –Stages of Gradual Metamorphosis: *Egg, Nymph, Adult (Grasshoppers, termites, cockroaches and dragonflies use gradual metamorphosis) Mollusks, Arthropods, and Echinoderms - Insects • An insect with gradual metamorphosis has no distinct larval stage. An egg hatches into a stage called a nymph, which usually looks like the adult insect without wings. Mollusks, Arthropods, and Echinoderms - Insects More on Insect Metamorphosis • Click the PHSchool.com button for an activity about insect metamorphosis. Mollusks, Arthropods, and Echinoderms - Arthropods Lyme Disease Cases • The graph shows the number of cases of Lyme disease by age group reported by Connecticut during one year. Mollusks, Arthropods, and Echinoderms - Arthropods Lyme Disease Cases • Reading Graphs: What variable is plotted on the y-axis? What does the first bar tell you? Cases per 100,000 people; the first bar indicates that for every 100,000 children under the age of 10, 200 had Lyme disease. Mollusks, Arthropods, and Echinoderms - Arthropods Lyme Disease Cases • Interpreting Data: Which age group is least at risk for Lyme disease? Explain. 20–29 year-olds; just over 50 per 100,000 people were infected. Mollusks, Arthropods, and Echinoderms - Arthropods Lyme Disease Cases • Interpreting Data: Which two age groups are most at risk? Children under 10 and people between the ages of 50 and 59 Mollusks, Arthropods, and Echinoderms - Arthropods Lyme Disease Cases • Calculating: Suppose a particular school in Connecticut has 1,000 students aged 10– 19. About how many of these students would you expect to get Lyme disease per year? One or two students Mollusks, Arthropods, and Echinoderms - Insects Insect Adaptations • Click the Video button to watch a movie about insect adaptations. Mollusks, Arthropods, and Echinoderms • • • • Phylum Echinodermata: Seastars 6,000 species of spinyskinned animals All have radial symmetry. “Echinoderm” means “spiny-skin”. Have an internal skeleton made of spines that extend out through the body. Mollusks, Arthropods, and Echinoderms • All live in the ocean. • Move using a water-vascular system and tube feet. • Most can regenerate lost body parts and can occasionally reproduce this way. Mollusks, Arthropods, and Echinoderms Characteristics of Echinoderms • Echinoderms, such as this sea star, have a water vascular system that helps them move and catch food. Tube Stomach Feet Madreporite Water Vascular System Mollusks, Arthropods, and Echinoderms - Echinoderms Water Vascular System Activity • Click the Active Art button to open a browser window and access Active Art about the water vascular system. Mollusks, Arthropods, and Echinoderms • Examples of echinoderms: 1. Sea stars and brittle stars: have 5 or more arms lined with tube feet. Feed on clams by inserting their stomach into the clam and digesting it inside the shell. Mollusks, Arthropods, and Echinoderms 2. Sea urchins and sand dollars: do not have arms. Covered with movable spines used for defense and movement. Mollusks, Arthropods, and Echinoderms 3. Sea cucumbers: leathery skin with no spines. Spits out its internal organs to confuse predators.