Classification of Animals — BIOLOGY STD 6 — Question

Arthropods are inverteberates with joined legs, segmented body and bilaterally symmetrical body which is divided into head, thorax and abdomen. Anthropods are further classified into –

• Arachnids – They have fused head and thorax, four pairs of legs, hard exoskeleton, no wings and antennae. Examples : Scorpions and spiders.
• Crustaceans – They have fused head and thorax, appendages on all segments, variable number of jointed legs and two pairs of antennae extending from the head. Examples: lobsters and shrimps.
• Myriapods – Body divided into large number of segments and have two pairs of legs per segment (example: millipede) or one pair of legs per segment (Example : centipede). Number of legs may vary from 20 to 200.
• Insects – Their body is divided into head, thorax and abdomen. They have three pairs of legs, two pairs of wings (some have one pair or none) and a pair of antennae. Examples : ants and butterflies.