Protostomia, Ecdysozoa

Phylum Nematoda

roundworms, pseudocoelomates, not segmanted, no circulatory system, complete digestive travt, longitudinal muscles, Ascaris

Phylum Arthropoda

body segmented, hard exoskeleton jointed appendages, “jointed feet,” nearly 1 million species

exoskeleton

thickened cuticle of chitin, flevible at joints

open circulatory system

hemolymph propelled by the heart through hemocoel (sinuses surounding tissue and organs

Subphylum Trilobita

all extinct, lived in Paleozoic shallow seas and disappeared during Permian extinction

Subpylum Chelicerata

have chelicerae, claw-like feeding appendages 2 classes

Class Merostoma

includes only 4 living species, horseshoe crabs

Class Arachnidia

scorpians, spiders, ticks, and mites, 8 legs

Subphylum Myripoda

centipedes and millipeds

Class Diplophota

milipeades, worm-like with two pairs of walking legs per segment

Class Chilopoda

centipedes, terrestrial carnivores, poisen claws

Subphylum Hexapoda

insects

Class Insects

very diverse group, many have 1 or 2 pairs of wings as extensions of the cuticle (not true appendages)

Malpighian tubules

metabolic waste removes off the digestive tract

tracheal system

tubes that take O2 directly to cells

air in

spiracles

Subphylum Crustacea

crabs lobsters, crayfish, shrimp, and barnacles

Class Maxillopoda

copoepods, very small crustaceans

Class Malacistraca

3 orders

Order Isopoda

pill bugs on land

Order Decapoda

crayfish, lobstes, crabs, and shrimp

carapace

dorsal side of cephalothorax

Order Euphausiace

krill