The Arthropods Keith Power

* Arthropods are by far the most successful of all animals * Well over 1,000,000 species * Some say over 30 million species of insects alone! * There are around 200 million individual insects alive at any given time for each human! * Arthropods exhibit these key features: * Exoskeleton: made of chitin, and must be molted (shed) in order to grow * Segmentation: the body is divided into sections * Jointed appendages: (arthropod means ‘jointed feet’) they may be modified into antennae, mouthparts or legs! UC Berkeley

* Key features of Arthropods cont. * Circulatory System: they have an open circulatory system (no veins or arteries) but a heart is present * Nervous system: they have a brain but also ganglia are in each segment. This results in the arthropod being able to carry out functions like eating, moving and reproducing without a brain present! * They also have compound eyes: hundreds or more of independent eyes

* Key features of Arthropods cont. * Respiratory System: Marine arthropods have gills * Spiders have book lungs (leaf-like plates within a chamber) * Terrestrial arthropods have tracheae (small branched ducts that eventually network to each cell) with the opening to the air called spiracles * Excretory System: aquatic arthropods diffuse most waste through gills, terrestrial insects have Malpighian tubules (slender projections from the digestive tract into the blood, wastes diffuses into them) 2004, Pearson Education

* Spiracles and trachea: Malpighian tubules: McGraw-Hill

* Digestion/feeding: varied and complex, range from predators to herbivores, complete digestive system present * Reproduction: sexual, lay eggs, may include metamorphosis * Movement: jointed appendages! Fly, walk, or swim Peter Pitman

* Class Chelicerata: spiders, mites, ticks, horseshoe crabs

* Class Crustacea: crabs, shrimps, lobsters, and pill bugs The Kids Window

* Class Crustacea: crabs, shrimps, lobsters, and pill bugs

Class Crustacea: crabs, shrimps, lobsters, and pill bugs

* Class Crustacea: Even barnacles!

* Crustacea anatomy: the crayfish * Chelipeds: for defense and prey capture * Swimmerets: for locomotion and reproduction (holds eggs) kentsimmons.uwinnipeg.ca

* Class Hexapoda: The insects!

* Insect Anatomy: * Body divided into three segments: head, thorax and abdomen * Mandible for crushing food

* Class Myriapoda: Centipedes and Millipedes