Phylum: Arthropoda, its classification and characteristics

  • largest phylum of animal kingdom.
  • found in every possible habitat of earth.
  • multicellular, triploblastic, bilaterally symmetrical, metamerically segmented, system grade of body organization.
  • jointed appendages for locomotion, food collection and sensory purposes.
  • body externally covered by hard chitinous cuticle.
  • body divided into head, thorax and abdomen. In some head and thorax fused to form cephalothorax.
  • complete alimentary canal.
  • mouth parts are adapted for various modes of feeding like chewing, piercing and sucking.
  • respiration through general body surface, gills, trachea or book lungs.
  • excretion by malphigian tubules or green glands.
  • haemocoelomate i.e. their body cavity is filled with blood.
  • open type of circulatory system consisting heart, arteries and blood sinuses.
  • well developed sensory organs including simple or compound eyes, antennae, statocyst (balancing organ), ocelli (photoreceptor).
  • mostly unisexual and development is indirect.

Phylum Arthropoda- Characteristics, classification, examples

 Image source: thebiologynotes


Arthropods are divided into 4 classes on the basis of locomotory organs. They are:

Class 1: Crustacea

  • mostly aquatic.
  • body divided into cephalothorax and abdomen.
  • head bears two pairs of antennae and stalked compound eyes.
  • five pairs of walking legs.
  • respiration by gills or general body surface.
  • excretion by green glands.
  • examples: Cancer (crab), Palaemon (prawn)

Class 2: Myriapoda

  • mostly terrestrial.
  • body divided into head and trunk or head, thorax and abdomen.
  • from each segment arises one or two pairs of walking legs.
  • head bears a pair of antennae.
  • respiration by trahea and excretion by malphigian tubules.
  • examples: Scolopendra (centipede), Julus (millipede)

Class3: Insecta

  • mostly terrestrial and some are aerial.
  • body divided into head, thorax and abdomen.
  • head bears a pair of antennae and a pair of compound eyes.
  • from thorax arises three pairs of legs and in some one or two pairs of wings.
  • excretory organ malphigian tubules and respiration by trachea.
  • examples: Periplaneta americana (cockroach), Pieris (butterfly), Bombyx (moth)

Class 4: Arachnida

  • mostly terrestrial, few are aquatic.
  • body is divided into cephalothorax (prosoma), and abdomen (ophisthosoma) or prosoma, mesosoma, metasoma.
  • head without antennae.
  • eyes are simple.
  • have four pairs of walking legs, a pair of chelicere and a pair of pedipalp.
  • respiration by book-lungs or general body surface.
  • examples: Aranea (spider), Palamnaeus (scorpion)

Animal Kingdom Arthropoda General Features And Classification – Otosection

 Image source: otosection

Class 5: Onychophora

  • small, terrestrial animals found below rocks, crevices, under logs, etc.
  • elongated worm like body without external segmentation.
  • appendages not joined but lobe like.
  • head bears a pair of antennae and simple eyes.
  • walking legs are lobe like terminating in claw.
  • respiration by trachea and excretion by nephridia.
  • examples: Peripatus (walking worm) i.e. connecting link between annelida and arthropoda.




Phylum: Arthropoda, its classification and characteristics