Arthropods can be grouped into several subphyla, with each of these subphyla then divided into different classes. The classification of phylum Arthropoda are as follows:

Crustacea

• They are aquatic, terrestrial, or parasitic.
• The head is fused with the thorax region known as the cephalothorax.
• Respiration occurs through gills or general body surface.
• The body is covered by a single large carapace.
• They possess two pairs of antennae and five pairs of appendages.
• They excrete through green glands or antennal glands.
• They have a pair of compound eyes and gonopores.
• Development is indirect. Larval stage is present.
• E.g., Daphnia, Palaemon.

Myriapoda

• These are mostly terrestrial.
• The body is elongated with numerous segments.
• The head is provided with antennae, two pairs of jaws, and a pair of simple eyes.
• They contain numerous legs.
• The upper lip of the mouth contains epistome and labrum, and the lower lip contains a pair of maxillae.
• A pair of mandibles is present inside the mouth.
• They respire by trachea and excretion occurs by malpighian tubules.
• E.g., Julus, Scolopendra.

Hexapoda

• They are mostly terrestrial.
• The body is differentiated into head, thorax, and abdomen.
• Head bears a pre-segmental acron.
• The thorax is divided into three segments.
• The abdomen has 7-11 segments.
• They have three pair of appendages.
• It has a pair of compound eyes
• They respire through gills and trachea.
• Malpighian tubules are the excretory organ.
• Development is indirect, and the larval stage is present. e.g., Tabernus, Mosquitoes, Ants

Chelicerata

• They are mostly found on land.
• The body is differentiated into cephalothorax and abdomen.
• Antennae are absent.
• The abdomen is divided into 13 segments.
• It has four pairs of interior appendages.
• They respire through trachea or gills.
• The Malpighian tubules help in excretion. E.g., Aramea, Limulus

Trilobitomorpha

• These are primitive arthropods and are extinct.
• They were found in abundance during the Paleozoic era.
• The body was divided into three lobes- one median and two lateral lobes.
• Head bore a pair of compound eyes and a pair of antennae.
• There was no structural differentiation of the body parts.
• The body was divided into head, thorax and pygidium.
• Appendages are biramous