Ch 28- Arthropods and Echinoderms

1. Ch 28- Arthropods and Echinoderms • Phylum Arthropoda • Most diverse and successful animals of all time • Segmented body, tough exoskelton, jointed appendages • Classified based on number and structure of their body segments and appendages • Mouthparts • Major groups include crustaceans, spiders and insects

2. Crustaceans • Subphylum Crustacea • Primarily aquatic • Crabs, shrimps, lobsters, crayfishes and barnacles • Have 2 pairs of antennae, 2 or 3 body sections, and chewing mouthparts- mandibles • Body is divided into cephalothorax and abdomen • 5 pairs of legs

3. Cephalothorax- formed by fusion of head with thorax • Thorax-body part lies just behind head where most internal organs are • Abdomen- posterior part of arthropod’s body • Carapace- part of exoskeleton that covers cephalothorax • Mandible- mouthpart adapted for biting and grinding food • Chelipeds- first pair of legs, have large claws for catching, picking up, crushing, and cutting food • Swimmerets- flipperlike appendages used by decapods for swimming • Barnacles- sessile, no abdominal segments and don’t use mandibles • Attach themselves to rocks and marine animals

4. Spiders and Their Relatives • Subphylum Chelicerata- Chelicerates • Horseshoe crabs, spiders, ticks, and scorpions • 2 body sections- cephalothorax and abdomen • 4 pairs of walking legs • Lack antennae • Book gills or book lungs • Chelicerae- mouthpart that contains fangs, used for stabbing and paralyzing prey • Pedipalps- long and modified for grabbing prey

5. Horseshoe crabs- oldest living arthropods • Chelicerae • 5 pairs of walking legs • Long spikelike tail • Spiders- largest group of arachnids • Spin silk webs • No teeth, paralyze prey and use digestive enzymes to break down prey’s tissue • Spinnerets- organs that contain silk glands • Video -- Black Widow: Most Venomous Spider in North America -- National Geographic • Mites and ticks- often parasitic • Chelicerae- needlelike structures used to pierce skin and suck blood • Scorpians- widespread in warm areas • Pedipalps enlarged into claws • Venomous stinger • Chew prey using chelicerae

6. Insects and their Relatives • Subphylum Uniramia or uniramians- centipedes, millipedes, and insects • Most species of all animals • Jaws, one pair of antennae, unbranched appendages • Centipedes- class Chilopoda • Few to 100 pairs of legs • One pair per body segment • Carnivores • Moist or humid areas • Millipedes- class Diplopoda • 2 pairs per body segment • Feed on dead, decaying plant material

7. Sec 3- Insects • What are the distinguishing features of insects? • Body divided into 3 parts- head, thorax, and abdomen • 3 pairs of legs attached to thorax

8. Metamorphosis • Process of changing shape and form • Under go either incomplete or complete metamorphosis • Incomplete metamorphosis- immature forms of insects look very much like adults • Nymphs- immature forms of adult insects • Lack functional sexual organs and wings • Complete metamorphosis- eggs hatch into larvae, look and act nothing like their parents and feed in different ways • Larva- look and act nothing like parents, feed in different ways and grow rapidly, molt a few times • Pupa- insect changes from larva to adult • Video -- Animals, Travel, Kids -- National Geographic

9. Sec 4- Echinoderms • What are the distinguishing features of echinoderms? • Spiny skin, internal skeleton, water vascular system, tube feet • Most exhibit 5-part radial symmetry • Phylum Echinodermata • Endoskeleton- an internal skeleton formed of hardened plates of calcium carbonate • Live only in the sea • Deuterostomes

10. Water vascular system- system of internal tubes, carries out many essential functions- respiration, circulation, movement • Madreporite- sievelike structure through which water vascular system opens to outside • Tube foot- structure that operates like suction cup, allows echinoderms to walk and pull open shells

11. Groups of Echinoderms • 7000 species of echinoderms • Live in oceans • Sea urchins and sand dollars, brittle stars, sea cucumbers, sea stars, sea lilies, and feather stars