Phylum – Arthropoda Salient Features

Phylum – Arthropoda
Phylum Arthrcpoda is the largest phylum oi animal kingdom including about 900,000 species in all habitats, which
constitute about 80% of all the known species of animals.
• This is the largest phylum of Animalia which includes insects.
• Over two-thirds of all named species on earth are arthropods.
• They have organ-system level of organisation.
• They are bilaterally symmetrical, triploblastic, segmented and coelomate animals.
• Structure: The body of arthropods is covered by chitinous exoskeleton.
• The body consists of head, thorax and abdomen.
• They have jointed appendages (arthros-joint, poda-appendages).
• Respiratory organs are gills, book gills, book lungs or tracheal system.
• Circulatory system is of open type.
• Sensory organs like antennae, eyes (compound and simple), statocysts or balance organs are present.
• Excretion takes place through malpighian tubules.
• They are mostly dioecious. Fertilisation is usually internal.
• They are mostly oviparous. Development may be direct or indirect.
• Examples:
• Economically important insects – Apis (Honey bee), Bombyx (Silkworm), Laccifer (Lac insect)
• Vectors – Anopheles, Culex Aedes (Mosquitoes)
• Gregarious pest – Locusta (Locust)
• Living fossil – Limulus (King crab).
• Classification