III. Cnidarians A. Have stinging cells

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1 Simple Invertebrates Chapter 15 Section 1 (pages ) I. Invertebrate Characteristics A. No backbone B. Three basic body plans 1. bilateral symmetry (insects) 2. radial symmetry (starfish) 3. asymmetrical (sponges) C. Neurons and Ganglia (the nervous system) 1. allow animals to sense their environment 2. carry messages around the body to control animal s actions 3. nerve cords are packages of neurons 4. ganglion = a concentrated mass of nerve cells D. Guts (the digestive tract) 1. a pouch lined with cells that release chemicals that break down food into small particles. 2. cells in the gut then absorb the food particles 3. coelom = a body cavity that surrounds the gut and contains the internal organs E. Make up about 96% of all animals on Earth II. Sponges A. Asymmetrical B. No tissues C. No gut 1. cannot make their own food (like plants) 2. eat by sweeping water into its body through pores 3. collar cells filter and digest food from the water D. No neurons E. Limited mobility, if at all F. Unusual abilities 1. regeneration = the ability to grow back G. Many different kinds of sponges all grow and live in the water III. Cnidarians A. Have stinging cells

2 1. painful and sometimes poisonous 2. use them to protect themselves and to catch food B. Have complex tissues C. Have a gut D. Have a simple network of nerve cells E. Are able to move freely F. Can regenerate G. Kinds of cnidarians 1. hydrozoan 2. jellyfish 3. sea anemone 4. coral IV. Flatworms A. Bilateral symmetry B. Three kings of flatworms 1. planarians a. head with sensory lobes and two eye spots b. live in freshwater or on land c. predators (carnivores) d. digest food in a gut e. well developed nervous system with a simple brain 2. flukes a. parasite live and reproduce in the bodies of other animals b. tiny heads with special suckers and hooks for attaching to animals 3. tapeworms a. parasite live and reproduce in the bodies of other animals b. no gut they simply attach to the intestines of another animal and absorb nutrients digested by its host V. Roundworms A. Bilateral symmetry B. Simple nervous system C. Decomposers or Parasites

3 Mollusks and Annelid Worms Chapter 15 Section 2 (pages ) I. Mollusks A. Where do they live - oceans, freshwater, land B. Classification 1. gastropods (stomach foot) snails and slugs 2. bivalves (double door) clams and some other two shelled shellfish 3. cephalopods (head foot) octopuses and squids C. How do they eat? 1. radula = tongue covered with curved teeth, used for scraping by snail and slugs 2. gills = used to filter tiny plants and bacteria from the water by clams and oysters 3. tentacles = long arms used to grab food and place it in the powerful jaws of squids and octopuses D. Ganglia and Brains 1. all have ganglia (masses of nerve cells) 2. cephalopods have large brains and are thought to be the smartest invertebrates E. Pumping Blood = Circulatory System transports materials through out the body in the blood 1. open circulatory systems = a circulatory system in which the blood is not contained entirely within vessels (most mollusks have this type of system) 2. closed circulatory system = a circulatory system in which the heart circulates blood through a network of blood vessels that form a closed loop (squids / octopuses) F. Mollusk Bodies 1. false foot (pseudopodia) = used to move the animals slowly (clams and snails) 2. visceral mass = gills, gut, and other organs 3. mantle = layer of tissue that covers and protects the visceral mass 4. shell = covers the mantle, protects the mollusk, keeps land mollusks from drying out II. Annelid Worms A. Segment = an identical, repeating body part B. Bilateral symmetry C. Closed circulatory system D. Complex nervous system with brain E. Habitat salt water, fresh water, and land F. Omnivores / Decomposers G. Classification

4 1. Earthworms a. 100 to 175 segments b. live in soil c. improve soil through castings (wastes), digging tunnels, and turning soil d. setae (stiff bristles) allow worm to move through the soil 2. Marine worms a. live in the ocean b. covered with many, and sometimes long, bristles c. very colorful d. eat mollusks or filter food from the water 3. Leeches a. parasites, scavengers, or predators of insects, slugs, and snails b. used in medicine to reduce swelling after surgery Arthropods Chapter 15 Section 2 (pages ) At least 75% of animal life on Earth are arthropods! I. Characteristics of Arthropods A. Segmented and Specialized Parts 1. are segmented like annelid worms 2. three main parts = head, thorax, abdomen 3. wings and legs are attached to the thorax B. Jointed Limbs 1. arthro = jointed 2. pod = foot C. External Skeleton 1. exoskeleton = a hard, external, support structure 2. made of chitin 3. muscles are attached to inside of exoskeleton 4. protects internal structures 5. helps keep water inside the body, arthropods can live on land without drying out D. Sensing Surroundings 1. well developed brain

5 2. bristles detect motion, vibration, pressure, and chemicals 3. compound eye = an eye composed of many light detectors 4. antenna = a feeler that is on the head that senses touch, taste, or smell E. Classification - based on number of body parts, legs, eyes, and antennae 1. Centipedes and Millipedes a. hard head b. one pair of antennae c. one pair of mandibles used to pierce and chew food d. number of legs pairs per segment 1) one pair = centipede 2) two pair = millipede 2. Crustaceans shrimp, barnacles, crabs, and lobsters a. live in water b. gills for breathing in water c. mandibles for eating d. two compound eyes on eyestalks e. two pair of antennae 3. Arachnids spiders, scorpions, mites, and ticks a. two main body parts cephalothorax and abdomen b. four pairs of legs c. no antennae d. chelicerae = claw like mouth parts e. simple eyes (sometimes as many as eight) f. carnivores (eat small insects) or parasites (drink the blood of the host) g. many helpful, some carry disease (ticks Lyme disease) 4. Insects largest group of arthropods a. three main body parts (head, thorax, abdomen) 1) head has one pair of antennae, one pair of compound eyes, and mandibles 2) thorax legs and wings (if present) are attached here 3) abdomen b. live everywhere but the ocean c. many helpful (pollinators), some harmful (eat crops), some carry diseases, bites and suck blood of prey

6 d. metamorphosis = a phase in the life cycle of many animals during which a rapid change from the immature form of an organism to the adult form takes place 1) complete metamorphosis four stages: egg, larva, pupa, and adult (butterflies, bees, beetles, flies) 2) incomplete metamorphosis three stages: egg, nymph (looks like a small adult, goes through a series of molting), and adult (grasshoppers and cockroaches) Echinoderms Chapter 15 Section 2 (pages ) I. Examples sea stars (starfish), sea urchins, and sand dollars II. Habitat all live in the ocean III. Eating Habits carnivores, omnivores, or herbivores IV. Spiny Skinned (echino = spiny; derm = skin) A. Endoskeleton = an internal skeleton made of bone or cartilage 1. spines are part of the endoskeleton, can be long and sharp or short and bumpy 2. endoskeleton can be hard and bony or stiff and flexible 3. skin covers the endoskeleton B. Symmetry 1. Larva bilateral symmetry 2. Adult radial symmetry C. Nervous System 1. simple (like jelly fish) 2. Nerve ring circle of nerve cells around the mouth 3. sea stars have radial nerves that run from the nerve ring to the tip of each arm 4. eyes that sense light are at the end of each arm of a sea star 5. cells cover the body that sense touch and chemical signals in the water D. Water Vascular System 1. a system of canals filled with a watery fluid that circulates throughout the body 2. helps the echinoderm move, eat, breathe, and sense its environment 3. sieve plate = water enters through holes in a flat plate on top of the sea star 4. ring canal = water flows through this tube around the mouth 5. radial canals = water flows through the arms 6. tube feet = suckers connected to the radial canals

7 a. used to move and capture food b. oxygen enters and wastes leave through the thin walls of the tube feet 7. ampulla = controls fluid pressure in tube feet a. allows tube feet to retract, extend, hang on, or let go b. coordinated efforts allows for slow movement E. Classification of Echinoderms 1. sea stars (starfish) 2. brittle stars and basket stars a. longer arms than sea stars b. smaller than sea stars c. do not have suckers on their tube feet 3. sea urchins and sand dollars a. are round b. endoskeleton forms a solid, shell-like structure c. no arms d. move with tube feet or on their spines e. use spines for movement and defense 4. sea lilies and feather stars a. 5 to 200 feathery arms b. sea lilies has body that sits on top of a long stalk c. feather stars do not have stalks 5. sea cucumbers a. no arms b. soft leathery body c. worm-like shape