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11-1 Mollusks • General - invertebrates - soft body covered with shell - mantle – thin tissue covers internal organs and produces shell - foot – muscular and is for crawling, digging, catching prey - found nearly everywhere - bilateral symmetry - organs: stomach, reproductive organs, kidneys that remove wastes - the water-living ones have gills to remove oxygen from water. The gills have blood vessels and are covered with cilia. - Radula – flexible ribbon of tiny teeth • Types: based on presence of shell, type of shell, type of foot, radulae, and complexity of nervous system Gastropods: ex. snail, slug - most numerous - snail has 1 shell, slug has no shell - creep with foot - herbivores/scavengers/carnivores - snails have trapdoor on foot used in case of danger or dry conditions Bivalves: ex. clam, oyster, scallop, mussels - 2 shells held by hinges and muscles - no radulae - filter feeders - gills to capture food - live in water - as adults stay in one place or move slowly - pearl: mantle in oysters forms a pearly coat around sand when sand enters the shell and mantle Cephalopod: ex. octopus, squid, nautilus - feet form tentacle around mouth to capture food and for protection - nautilus has external shell, squid has internal, octopus has none - large eyes for excellent vision; large brain; they are intelligent and can remember - live in ocean and move by jet propulsion 11-2 Arthropods General • invertebrates • external skeleton called exoskeleton - waxy/waterproof - for protection - made of chitin (tough/flexible) - molts (sheds the old one to be replaced by a new one; during this time the organism is soft and has less protection) • segmented body • jointed appendages (wing, leg, claw, mouth parts, antenna) for flexibility and movement • open circulatory system • mostly sexual reproduction; either male or female; internal fertilization • live everywhere Earthworms and Arthropods are both segmented but are not related as shown through their DNA analysis. Types 1. Crustaceans (shrimp, crab, barnacle, krill) - 2 or 3 body sections - 3 pairs of appendages for chewing - 5 or more pairs of legs - 2 pairs of antennae - go through metamorphosis (body changes) - live in watery environment; get oxygen through gills - eat dead plants/animals; some are predators, others are herbivores 2. Arachnids (spiders, mites, ticks, scorpions) - 2 body sections with the head and chest in the first and the digestive/reproductive organs in the hind/back section (abdomen) - 8 legs - no antennae - breathe with book lungs (tiny tubes leading into the exoskeleton) Spiders Mites some - predators/herbivores - some spin webs to trap prey parasites - hollow fangs, inject venom Ticks parasites, cause diseases like Lyme Disease Scorpions - live in hot climates - nocturnal - stingers 3. Centipedes and Millipedes - both are highly segmented; centipedes have one pair of legs/segment, millipedes have 2 pairs of legs/segment - centipedes are predators with sharp jaws to inject venom, millipedes are herbivores and curl up and squirt a bad-smelling liquid when disturbed 11-3 Insects (butterfly, cockroach, bee) Body sections - head (1 pair of antennae, simple eyes for light/dark, 2 compound eyes for movement) - thorax (1-2 pairs of wings, 6 legs) - abdomen (internal organs; get oxygen through tubes leading to exoskeleton) Metamorphosis (egg to adult) - complete: egg, larva which does not resemble the adult, pupa (cocoon), adult. Ex. most flies, ants - gradual: egg, nymph which looks like the adult, adult. Ex. grasshopper, termite, cockroach, dragonflies Feeding They eat animals, blood, animal droppings, decaying bodies Defense - hard exoskeleton run/fly fast smell/taste bad stings camouflage resemble other animals Insects and Humans - harmful ~ damage crops ~ carry disease-causing organisms, ex. mosquitoes carrying malaria causing parasites - helpful ~ bees make honey ~ silkworms make silk ~ help pollination ~ biological control; this a method of using natural insect predators to get rid of harmful insects; it doesn’t harm the helpful ones unlike pesticides and insects can’t become resistant 11-4 Communication • Pheremones: chemicals released by one animal that affect the behavior of another animal of the same species • Pheremones are used to locate food, attract mates, distinguish members of own kind. • Pheremones are specific; each has different shape and therefore affect the same species only. • Some pheremones are made in the lab and used to eliminate pest insects by trapping them and killing or destroying sperm with x-rays. • Communication with light produced by the animal is called bioluminescence. Ex. fireflies use it to attract mates. 11-5 Echinoderms • General - invertebrate - radial symmetry; 5-part - on ocean floor - water vascular system: tubes with fluid inside contract and send the fluid to tube feet that act as suction cups for slow movement - internal skeleton called endoskeleton - spiny skin - external fertilization in water - metamorphosis (egg-larva-adult) - regeneration • Types a. sea stars - eyespot on each arm to sense light - reproduce by splitting - use arms and tube feet to move and capture prey; partially digests food outside then takes in b. brittle stars - arms to move; no suction cups so tube feet not used for moving - get food by tube feet c. sand dollar and sea urchin - no arms; move by tube feet; burrow in sand - teeth to scrape food d. colorful sea cucumbers - no arms; crawl with tube feet - filter feeders; use tentacles to sweep food into mouth