General Characteristics and Classificatio

Phylum Arthropoda is the largest animal group which constitutes the largest percentage of the world’s organisms. It is estimated that about 84% of all known species of animals belong to this phylum. This phylum includes several large classes and contains the class Insecta which itself represents a major portion of the animal species in the world. They possess the ability to survive in every habitat.

The term “Arthropoda” is derived from two Greek words ‘arthros’ meaning ‘joint’ and ‘podos’ meaning ‘leg’. Hence the word “Arthropoda” means “jointed legs”. Arthropods are protostomic, eucoelomic organisms and they have functional segmentation body with a pair of the jointed appendage. They also have a bilaterally symmetrical body with external chitinous cuticle. Some species of arthropods bear wings for aerial movement. They are the successful animal groups which show a great variety of adaptations. Among them, some live-in aquatic environments, some inhabit in terrestrial habitat and others are adapted for aerial habitats.

The arthropoda characteristics are mentioned below:

• The body is triploblastic, segmented, and bilaterally symmetrical.
• They exhibit organ system level of organization.
• The body is divided into head, thorax, and abdomen.
• Their body has jointed appendages which help in locomotion.
• The coelomic cavity is filled with blood.
• They have an open circulatory system.
• The head bears a pair of compound eyes.
• The exoskeleton is made of chitin.
• The terrestrial Arthropods excrete through malpighian tubules while the aquatic ones excrete through green glands or coaxal glands.
• They are unisexual and fertilization is either external or internal.
• They have a well-developed digestive system.
• They respire through the general body surface or trachea.
• They contain sensory organs like hairs, antennae, simple and compound eyes, auditory organs, and statocysts.