Chapter 28 Arthropods and Echinoderms. Body Terms. Evolution has led to:

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Chapter 28 Arthropods and Echinoderms Introduction to Arthropods jointed feet

bodies Tough exoskeleton Jointed appendages Body Terms Exoskeleton-external

carbohydrate called chitin Much variation on exoskeletons Terrestrial

) have waxy covering to prevent water loss Appendages- structures like legs

segments The body segments fused together Highly specialized appendages For

tails, mouthparts and walking legs Form and Function Feeding Varied eating

detritivores, parasites Varied mouthpartspincers, fangs, jaws Respiration

Spiracles-small openings alongside the body that allow air to enter and leave

1 Chapter 28 Arthropods and Echinoderms Introduction to Arthropods jointed feet Most diverse and successful animals Over 750,000 species identified Segmented bodies Tough exoskeleton Jointed appendages Body Terms Exoskeleton-external skeleton that protects and supports the body Made of protein and a carbohydrate called chitin Much variation on exoskeletons Terrestrial arthropods (Ter. Arth.) have waxy covering to prevent water loss Appendages- structures like legs and antennae that extend from the body wall Evolution has led to: Fewer body segments The body segments fused together Highly specialized appendages For feeding, movement, and more Legs became: antennae, claws, wings, flippers, tails, mouthparts and walking legs Form and Function Feeding Varied eating habitsherbivores, carnivores, omnivores Bloodsuckers, filter feeders, detritivores, parasites Varied mouthpartspincers, fangs, jaws Respiration Tracheal tubes-branching, air filled tubes that are in many ter. arth. Spiracles-small openings alongside the body that allow air to enter and leave the tracheal tubes Book lungs-organs with layers of respiratory tissue stacked ex) spiders Gills- used by aquatic arthropods ex) crabs Book gills-used by horseshoe crab 1

Circulation Open circulatory system-well developed heart pumps blood arteries tissues sinus collects around the heart and

to feces to move through the gut Used in ter. Arth.

Response All have a brain Well developed nervous system Two nerves around the esophagus connect brain to the central nervous

system Individual muscles cells Muscles generate force (to fly, walk, swim) by contracting a muscle and pulling on the

2 Circulation Open circulatory system-well developed heart pumps blood arteries tissues sinus collects around the heart and re-enters to be pumped through again Excretion Malpighian tubules-saclike organs that extract wastes from blood and add them to feces to move through the gut Used in ter. Arth. Diffusion- moves cellular waste from the body to the water Used in aquatic arth. Response All have a brain Well developed nervous system Two nerves around the esophagus connect brain to the central nervous cord Connects the ganglia which coordinate movement of legs and wings Movement Well developed muscles controlled by nervous system Individual muscles cells Muscles generate force (to fly, walk, swim) by contracting a muscle and pulling on the exoskeleton Reproduction and Molting Terrestrial Internal fertilization Aquatic Internal and external fertilization Molting When an arthropod sheds its entire exoskeleton and makes a larger one in its place Controlled by the endocrine system with hormones 2

Subphyla of Arthropods Crustacea crabs, shrimp, crayfish Chelicerata spiders, ticks, scorpions Uniramia millipedes,

plates of calcium carbonate Gives bumpy, irregular surface Only live in the sea No cephalization Two sided-oral

called tube feet 5 part radial symmetry (body parts in multiples of 5) Larvae- bilaterally symmetrical Deuterostomes

circulation and movement Madreporite-opening to the outside through which water passes Connects to ring canal which

movement and feeding Feeding Urchins- scrape algae Sea lilies-capture floating plankton Sea cucumbers-take in sand and

3 Subphyla of Arthropods Crustacea crabs, shrimp, crayfish Chelicerata spiders, ticks, scorpions Uniramia millipedes, centipedes Class Insecta (no subphylum) 3 part body, 3 pairs of legs 28-4 Echinoderms spiny skin Endoskeleton- hardened plates of calcium carbonate Gives bumpy, irregular surface Only live in the sea No cephalization Two sided-oral mouth)/aboral (with Echinoderm Characteristics Spiny skin Internal skeleton Water vascular system Suction cup structure called tube feet 5 part radial symmetry (body parts in multiples of 5) Larvae- bilaterally symmetrical Deuterostomes (indicates similarity to vertebrates) Water Vascular System Carries out essential body functions like respiration, circulation and movement Madreporite-opening to the outside through which water passes Connects to ring canal which extend out into radial canals along the 5 arms Tube feet-suction cups on the underside of the body that help with movement and feeding Feeding Urchins- scrape algae Sea lilies-capture floating plankton Sea cucumbers-take in sand and detritus off sea floor Sea stars-use tube feet to pull open bivalves, push stomach out, pour enzymes and digest mollusks, brings back stomach into body 3

Respiration and Circulation Water vascular system In most

some,skingills for gas exchange Excretion Digestive wastes-

Response and Movement Don t have highly developed nervous

detect light External fertilization Separate sexes

joints Urchins Sand dollars Groups of Echinoderms Brittle

Ecology Urchins control algae Sea stars control clams and

4 Respiration and Circulation Water vascular system In most species, thin walled tissues of tube feet for respiration In some,skingills for gas exchange Excretion Digestive wastes- feces through anus Ammonia excreted through tube feet Response and Movement Don t have highly developed nervous system Nerve ring around the mouth Sensory organs that detect light External fertilization Separate sexes Reproduction Tube feet Endoskeleton structure/flexible joints Urchins Sand dollars Groups of Echinoderms Brittle stars Sea cucumbers Sea stars Sea lilies Feather stars Ecology Urchins control algae Sea stars control clams and corals Crown of Thorns Feeds on corals Rows of poisonous spines on arms Great Barrier Reef damage 4

5 one-step-beyond-crown-of-thornsstarfish-video.htm 5

28 2 Groups of Arthropods

28 2 Groups of Arthropods 1 of 42 28 2 Groups of Arthropods Arthropods are classified based on the number and structure of their body segments and appendages particularly their mouthparts. The three major