Biology | Arthropoda » Diversity of Life, insects, crustaceans, spiders, mites

Source: http://www.doksinet Diversity of Life -Arthropoda - (insects, crustaceans, spiders, mites) Source: http://www.doksinet Arthropoda - insects, crustaceans, spiders, mites, Source: http://www.doksinet Arthropoda - abundance Source: http://www.doksinet Arthropoda – Where did they come from? Peripatus Source: http://www.doksinet What about the Onychophora (“velvet worms” )? Annelid Characteristics Arthropod Characteristics -worm-like body -segmented legs (during embryogenesis) -paired nephridia -open circulatory system - hemocoel - trachea - oral appendages Peripatus Source: http://www.doksinet Arthropoda - What makes them all arthropods? Arthropods are • segmented coelomates • exoskeleton • jointed appendages Source: http://www.doksinet Arthropoda - two significant improvements in body

architecture 1. 2. EXOSKELETON JOINTED APPENDAGES Source: http://www.doksinet Arthropoda - Exoskeleton exoskeleton heart digestive cavity ventral nerve cord Source: http://www.doksinet 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 Source: http://www.doksinet Arthropoda - Exoskeleton = Laid down in overlapping layers (like plywood) Source: http://www.doksinet Arthropoda - Exoskeleton Advantages: 1. Protection from drying - allowed invasion of land 2. Protection from predators - Source: http://www.doksinet Arthropoda - Exoskeleton Advantages: 1. Protection from drying - allowed invasion of land 2. Protection from predators - Disadvantages: 1. Doesn’t permit growth - have to moult 2. Doesn’t bend - need to insert breaks (joints) in it

to permit movement Source: http://www.doksinet Arthropoda - Body Sections Thorax - locomotory Abdomen - digestion and reproduction Head - sensory and feeding Source: http://www.doksinet Arthropoda - Classification THE MAIN GROUPS OF ARTHROPODS 1. CHELICERIFORMES - spiders, mites, ticks, scorpions 2. MYRIAPODA - centipedes and millipeds 3. UNIRAMIA - insects 4. CRUSTACEA - crabs, lobsters, shrimp Source: http://www.doksinet Arthropoda - Cheliceriformes Horseshoe crab Spider Scorpion Source: http://www.doksinet Arthropoda - Cheliceriformes Characteristics 1. Chelicerae - feeding appendages 2. Head and thorax are fused - cephalothorax 3. Eight legs Source: http://www.doksinet Arthropoda - Myriapoda - millipedes and centipedes Characteristic - several pairs of legs Source: http://www.doksinet Arthropoda - Uniramia - the insects Most common kind of animal - greatest number of species

Protozoa Meso/Placozoa Porifera Cnidaria Platyhelminthes Pseudocoelomates Annelida Minor inverts Insecta Other arthropods Mollusca Lophophorates Echinodermata Hemi/Urochordata Vertebrates Source: http://www.doksinet Arthropoda - Uniramia - the insects Most common kind of animal - greatest number of species Source: http://www.doksinet Arthropoda - Uniramia - the insects Most common kind of animal - greatest number of species Characteristics - 1. Six legs 2. Distinct head, thorax and abdomen Source: http://www.doksinet Arthropoda - Uniramia - the insects Characteristics 3. Wings Insects are the only invertebrates to have mastered flight Source: http://www.doksinet Arthropoda - Uniramia - the insects Characteristics - 3. Two kinds of life cycles Complete (or holometabolous) Egg larva pupa adult Incomplete (or hemimetabolous) Egg larva

adult Source: http://www.doksinet Arthropoda - Crustacea - lobsters, crabs, barnacles Source: http://www.doksinet Arthropoda - Crustacea - lobsters, crabs, barnacles Characteristics - 1. Head and thorax are fused - cephalothorax Source: http://www.doksinet Arthropoda - Crustacea - lobsters, crabs, barnacles Characteristics - 2. 10 primary locomotory appendages Source: http://www.doksinet Arthropoda - Summary of characteristics Group Cheliceriformes Uniramia Myriapoda Crustacea Cephalothorax Yes No No Yes Number of legs 8 6 20+ 10 Flight No Yes No No Jointed appendages Yes Yes Yes Yes