(insects, crustaceans, spiders, mites) Diversity of Life -Arthropoda - (insects, crustaceans, spiders, mites)

Arthropoda - insects, crustaceans, spiders, mites,

Arthropoda - abundance

Arthropoda – Where did they come from? Peripatus

What about the Onychophora (“velvet worms” )? Annelid Arthropod Characteristics Characteristics -worm-like body -segmented legs (during embryogenesis) Peripatus -paired nephridia -open circulatory system - hemocoel - trachea - oral appendages

Arthropoda - What makes them all arthropods? Arthropods are • segmented coelomates • exoskeleton • jointed appendages

Arthropoda - two significant improvements in body architecture EXOSKELETON JOINTED APPENDAGES

Arthropoda - Exoskeleton heart digestive cavity ventral nerve cord

Arthropoda - Exoskeleton The arthropod exoskeleton is made of chitin (also found in the cell walls of fungi) Chains of sugars - cross-linked with benzene N-acetyl - glucosamine Benzene rings

Arthropoda - Exoskeleton = Laid down in overlapping layers (like plywood)

Arthropoda - Exoskeleton Advantages: Protection from drying - allowed invasion of land Protection from predators -

Arthropoda - Exoskeleton Advantages: Protection from drying - allowed invasion of land Protection from predators - Disadvantages: Doesn’t permit growth - have to moult Doesn’t bend - need to insert breaks (joints) in it to permit movement

Arthropoda - Body Sections Thorax - locomotory Abdomen - digestion and reproduction Head - sensory and feeding

Arthropoda - Classification THE MAIN GROUPS OF ARTHROPODS CHELICERIFORMES - spiders, mites, ticks, scorpions MYRIAPODA - centipedes and millipeds UNIRAMIA - insects CRUSTACEA - crabs, lobsters, shrimp

Arthropoda - Cheliceriformes Horseshoe crab Spider Scorpion

Arthropoda - Cheliceriformes Characteristics 1. Chelicerae - feeding appendages 2. Head and thorax are fused - cephalothorax 3. Eight legs

Arthropoda - Myriapoda - millipedes and centipedes Characteristic - several pairs of legs

Arthropoda - Uniramia - the insects Most common kind of animal - greatest number of species

Arthropoda - Uniramia - the insects Most common kind of animal - greatest number of species

Arthropoda - Uniramia - the insects Most common kind of animal - greatest number of species Characteristics - Six legs 2. Distinct head, thorax and abdomen

Arthropoda - Uniramia - the insects Characteristics 3. Wings Insects are the only invertebrates to have mastered flight

Arthropoda - Uniramia - the insects Characteristics - 3. Two kinds of life cycles Complete (or holometabolous) Egg larva pupa adult Incomplete (or hemimetabolous) Egg larva adult

Arthropoda - Crustacea - lobsters, crabs, barnacles

Arthropoda - Crustacea - lobsters, crabs, barnacles Characteristics - 1. Head and thorax are fused - cephalothorax

Arthropoda - Crustacea - lobsters, crabs, barnacles Characteristics - 2. 10 primary locomotory appendages

Arthropoda - Summary of characteristics Group Cheliceriformes Uniramia Myriapoda Crustacea Cephalothorax Yes No Number of legs 8 6 20+ 10 Flight Jointed appendages