2.+Phylum;+Arthropoda

3. Class; Arachnida Arachnids are joint-legged invertebrates. They have 8 legs although in some animals these have taken on a sensory role. Arachnida comes from the Greek word meaning spider. There are around 100,000 named species. 3. Class; Insecta Animals in the class Insecta have an exoskeleton, a three-part body, three pairs of jointed legs, compound eyes and two antennae. The word Insecta comes from the Greek //'insectum'// meaning cut into sections. There are believed to be between 6 and 10 million species. 3. Class; Malacostraca Malacostraca are crustaceans who have 20 body segments divided into head, thorax and abdomen.They live in all marine environments and have even colonised habitats on land. Malacostraca come from the Greek //'malakos'// meaning soft and //'ostrakon'// meaning shell. This is a little misleading as Malacostracan shells are soft only after moulting. Malacostraca contains over 25,000 existing species.