Chapter 31 Arthropods Examples insects crustaceans arachnids centipedes

Chapter 31: Arthropods Examples: insects, crustaceans, arachnids, centipedes, millipedes

Most diverse phylum

Features of Arthropods “Jointed” appendages Segmented body: head, thorax, abdomen, cephalothoraxes – fused head and thorax – (arachnids)

Eyes of Arthropods Compound eyes – eye with many units Simple eyes – Single lens, see light and dark only, not image

Exoskeleton Made of chitin Purpose: Molting – shedding exoskeleton

Respiration Varies from group to group. Examples: trachea with spiracles Gills (aquatic) Book lungs (arachnids)

Open Circulatory System

Excretory System Malpighian tubules – sort of like our kidneys. Structures that filter blood.

I. Arachnids-unique characteristics Examples: spiders, scorpions, ticks, daddy long legs Eight legs 2 body segments: cephalothorax, abdomen Chelicerae – fangs Breath by using book lungs or tracheal tubes

Unique Feeding of Spiders can bite All have venom Spin web for capture

Brown Recluse

Brown Recluse

Wolf Spider

Tarantula

Camel spider

Scorpions Poisonous Stinger, Nocturnal

Household Dust mite

II. Insects Largest group on earth 3 Body sections: – Head – mouthparts, antennae – Thorax- 3 pairs of legs – abdomen – spiraclesorgans for breathing, open to tracheal tubes

Insect life cycle Metamorphosis – physical change Two types – complete and incomplete Complete – – 1. Larva – 2. Chrysalis- cocoon – 3. Pupa – inside cocoons – 4. Adult

Pupa stage with chrysalis

Adult stage

Incomplete Metamorphosis Less of a change 1. Egg 2. Nymph – a smaller version of the adult with no wings 3. Adult

Success of Insects Found everywhere Short life span, adapt to change quickly Flight – Elaborate social systems

Head Lice

III. Crustaceans Examples: crayfish, lobsters, pill bugs, crabs, barnacles Use gills

IV: Millipedes and centipedes -1 Pair of legs per segment -2 pair of legs per segment -Painful bite -Herbivores

Ch. 32 Echinoderms

Features of Echinoderms Spiny, marine invertebrates Endoskeleton – purpose is for protection, muscle attachment – Ossicles with spines Begin as bilateral, free-swimming larvae

Features of Echinoderms Radial symmetry as an adult

Water Vascular System of canals Used for locomotion, feeding and gas exchange Water flow through canals: – – Madreporite Ring canal Radial canals Tube feet – used for locomotion

Ventral surface of sea star

Additional Characteristics Nervous system: ring of nerves, eyespots Ability to regenerate Diet – hetertrophs: corals, worms, mollusks Some are herbivores

Wrap up Echinoderms Seastars Brittle stars Sea urchins Feather Stars

Group 1: Sea Stars

Brittle Stars Highly flexible arms, no anus, also feet on detritus – bottom dweller, regeneration

Feather Stars Not sessile, but like to be, sticky arms, nocturnal

Sea Cucumbers Regeneration of organs, tube feet

Sea Urchins Scrape algae off of rocks, sponges, tube feet