Phylum Arthropoda

ARTHROPODS Largest Phylum o Insects Bilateral symmetry Segmented bodies Exoskeleton of chitin & protein o Ecdysozoa

Paired, jointed appendages o Swimming o Walking o Sensory structures o Manipulation of food Nervous system o Cerebral ganglia (brain) o Ventral nerve cord o Antennae o Many have compound eyes Open circulatory System Specialized respiratory structures o Gills, Tracheae, Book lungs

A Survey of Arthropods A Survey of Arthropods

Subphylum Myriapoda Centipedes (Chilopoda) 1 pair legs/segment Carnivorous Long legs – run rapidly Poison claws on 1 st segment behind head Millipedes (Diplopoda ) 2 pairs legs/segment Herbivores Crawl slowly

Arachnids Cephalothorax and abdomen 6 pairs of jointed appendages Gas exchange by tracheae, book lungs, or both

Crustaceans Primarily aquatic – gills Hard mandibles for biting and grinding Maxillae Decapods Chelipeds

Insects Most numerous and diverse group on the planet 6 legs; many have wings 3 distinct body regions: head, thorax, and abdomen Sensory organs: o 1 pair of antennae o simple and compound eyes

Respiration o Spiracles  trachea o Allows for high metabolic rate Excretion through Malpighian tubules o Discharged into intestine Separate sexes o Fertilization is internal Several molts occur during development

Metamorphosis Incomplete or complete Incomplete : egg  larva (w/o functional wings)  adult

Complete: egg  larva  pupa  adult

Other Adaptations of Insects… Behavior: Some insects are social: bees, ants Pheromones

Success of Insects Exoskeleton Segmentation Jointed appendages Flying Reproductive capability – many eggs, protected by thick membrane Defensive and offensive capability