Invertebrates 4 Phylum Arthropoda

Phylum Arthropoda: “jointed foot”

Basic Arthropod Features (cont.) Paired, jointed appendages joints allow for flexibility Segmentation In some, have similar segments throughout body In most: Segments combined into specialized body regions Crustaceans have 2 regions: cephalothorax, abodomen Insects have 3 regions: head, thorax and abdomen Exoskeleton Same materials also in mouthparts, wings, eye lens

Focus on Molting Function: growth New exoskeleton built under old stretching by water or air in the digestive system and hemocoel vulnerable to predators while hardening mating can coincide with soft shell in female crabs Some arthropods grow all life Hormonal control

Subphylum Crustacea Examples: Lobsters, crabs, shrimp, barnacles, copepods, etc..

Subphylum Unirama Insects, centipedes, millipedes

Subphylum Chelicerata Spiders, mites, scorpions, horseshoe crabs

Various aspects of anatomy, physiology and behavior Feeding Class Crustacea Class Insecta Subphylum Chelicerata Circulation/gas exchange Open circulatory system Respiration varies amongst subphyla and classes Class Crustacea: gills Class Insecta: tracheal system. CARRIES OXYGEN AND CO2 Subphylum Chelicerata: tracheal system, book gills and book lungs Water/ion balance and ammonia excretion Crustacea: gills and green glands Insecta and Chelicerata: Malpighian tubules

Various aspects of anatomy, physiology and behavior Nervous system Cerebral ganglia Ventral nerve cord (paired, fused) Ganglia in each segment , or one ganglion for several segments Reproductive systems Usually internal fertilization Spermatophores Sperm storage

Review: Features