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