Phylum Phylum ArthropodaArthropoda

ARTHROPODSARTHROPODS• Largest Phylum

o Insects

• Bilateral symmetry

• Segmented bodies

• Exoskeleton of chitin & proteino Ecdysozoa

• Paired, jointed appendageso Swimmingo Walkingo Sensory structureso Manipulation of food

• Nervous systemo Cerebral ganglia (brain)o Ventral nerve cordo Antennaeo Many have compound eyes

• Open circulatory System

• Specialized respiratory structureso Gills, Tracheae, Book lungs

A Survey of A Survey of ArthropodsArthropods

Subphylum MyriapodaSubphylum Myriapoda

Centipedes (Chilopoda)

•1 pair legs/segment•Carnivorous•Long legs – run rapidly•Poison claws on 1st segment behind head

Millipedes (Diplopoda)

•2 pairs legs/segment•Herbivores•Crawl slowly

ArachnidsArachnids

• Cephalothorax and abdomen

• 6 pairs of jointed appendages

• Gas exchange by tracheae, book lungs, or both

CrustaceansCrustaceans

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

InsectsInsects• 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 antennaeo simple and compound eyes

• Respirationo Spiracles tracheao Allows for high metabolic rate

• Excretion through Malpighian tubuleso Discharged into intestine

• Separate sexeso Fertilization is internal

• Several molts occur during development

MetamorphosisMetamorphosis• Incomplete or complete

• Incomplete :

egg larva (w/o functional wings) adult

• Complete:

egg larva pupa adult

Other Adaptations of Other Adaptations of Insects…Insects…

• Behavior: http://video.google.ca/videoplay?docid=5867193301785656504

• Some insects are social: bees, ants

• Pheromones

Success of InsectsSuccess of Insects• Exoskeleton

• Segmentation

• Jointed appendages

• Flying

• Reproductive capability – many eggs, protected by thick membrane

• Defensive and offensive capability