The Fascinating Biology of Arthropods: Unveiling Nature's Exoskeletal Wonders

Aristotle first described crabs and some decapods. He named them Malacostraca.

Linnaeus kept Malacostraca under Insecta. Lamarck divided this insect into three classes.

1. Crustacea
2. Hexapoda
3. Arachnida

The name Crustacea was first used by Cuvier.

Von Setbold in 1845 combined Crustacea, Arachnida, and Hexapoda into an independent group. He called this group "Arthropoda".

Arthropoda means "jointed legs". This phylum includes animals with jointed legs. These animals are metamerically segmented, true coelomate, and bilaterally symmetrical.

This is the biggest phylum and it includes about 80% of the known animal species.

Arthropoda is the largest and most successful phylum in terms of number, distribution, and adaptations. It is the dominant group in the present day. This is the only invertebrate phylum that includes flying forms. The segments bear appendages. These appendages are jointed. Hence the name Arthropoda. Their body is covered by a chitinous outer exoskeleton. The hard exoskeleton restricts growth, this is overcome by periodic shedding of the exoskeleton, which is called ecdysis. In these animals, muscles are arranged segmentally. All these muscles are striated.

These animals show definite organ systems. The body cavity contains blood called Haemocoel. Excretion is performed by green glands or malpighian tubules. The nervous system includes the brain and double ventral nerve cord. Compound eyes are seen in the majority of the arthropods. Respiration is by gills, gill books, book Kings, tracheae, etc. Sexes are separate; often there is sexual dimorphism. Fertilization is internal.

Arthropods occur on land, in the soil, in freshwater, in seawater, and in the bodies of other animals and plants.