Arthropods

2.   All arthropods exhibit the following characteristics.   Check the ones that are UNIQUE to arthropods.

Bilateral symmetry

Open circulatory system

Segmented body

Jointed legs with claws

Exoskeleton

Complete digestive system

Specialized excretory organs

3.   Most arthropods can be divided into two groups:   those with mandibles (Mandibulata), and those with fangs (Chelicerata).   Find at least five members of each group from the list in question #1 and enter them in the boxes below.

Mandibulata	Chelicerata
Select                       Spiders Crayfish Ants Ticks Millipedes	Select                       Spiders Crayfish Ants Ticks Millipedes
Select                       Lice Ticks Scorpions Shrimp Beetles	Select                       Lice Ticks Scorpions Shrimp Beetles
Select                       Grasshoppers Pillbugs Barnacles Sea spiders Mites	Select                       Grasshoppers Pillbugs Barnacles Sea spiders Mites
Select                       Horseshoe crabs Flies Earwigs Centipedes Spiders	Select                       Horseshoe crabs Flies Earwigs Centipedes Spiders
Select                       Scorpions Mites Sea spiders Silverfish Crabs	Select                       Scorpions Mites Sea spiders Silverfish Crabs

4.   Think!     What physical characteristics are used to distinguish between "primitive" and "advanced" arthropods?   How reliable are these characteristics?   What practical value is there in asking these questions?