Maharashtra State PSC Model Paper 3

Concept:

• The phylum Arthropoda is the biggest phylum. It comprises two-thirds of all the named species on earth.
• Arthro means ''joints'' and poda means ''appendages'' so most of the arthropods bear joined appendages.
• Their bodies are segmented and an exoskeleton is present, made up of chitin.
• The arthropods can be divided into 6 classes - Crustacea, Chelicerata, Myriapoda, Hexapoda, Trilobitomorpha and, Onychophora.

Explanation:

• Crustaceans exhibit both terrestrial and aquatic habitat, based on the habitat they can respire through gills or trachea.
• The body has two divisions cephalothorax (head + thorax) and abdomen.
• They have two pairs of Antennae, Maxillae, and a single pair of mandibles.
• Antennal glands or Green glands are present for excretion.