Phylum Arthropoda MCQ - Practice Questions with Answers

• The term ‘Arthropoda’ is derived from Greek words 'arthros' that means jointed and 'podos' that means leg. 
• These animals have jointed appendages.
• It is the largest phylum of the Kingdom Animalia with a documentation of 85% species.
• They have a segmented body. 
• They are triploblastic and haemocoelomic.  
• They occupy terrestrial, aquatic and aerial habitats

Examples:

• Economically important insects – Apis (Honey bee), Bombyx (Silkworm), Laccifer (Lac insect)
• Vectors – Anopheles, Culex and Aedes (Mosquitoes)
• Gregarious pest – Locusta (Locust) Living fossil – Limulus (King crab).

Body Plan of Arthropoda:

• They possess a tough chitinous exoskeleton. These are the first animals to develop voluntary muscles. The degree of segmentation in animals varies.

Based on body divisions , this phylum is divided into seven  classes

Class 1 : Crustacea : The body is divisible into cephalothorax (head and thorax fused) and abdomen and tough carapace covers the body. Prawns and Crabs belong to this class

Class 2 : Chilopoda : Body is divided into head and trunk. Centipede is an example

Class 3 : Diplopoda : Body is divisible into head, thorax and abdomen. Millipide is an example

Class 4 : Insecta (Hexapoda) : Body is divisible into head, thorax and abdomen. Thorax shows three pairs of legs. All insects belong to this class. This is the largest class 

Class 5 : Arachnida : Body is divisible into Cephalothorax and abdomen.  Spiders belong to this class

Class 6 : Onychophora : Example Peripatus

Class 7 : Merostomata : Example Limulus

Respiration in Arthropoda:

• There is a variety in the respiratory organs in arthropods depending on the habitat:
• The terrestrial arthropods breathe through network of tracheal tubes connected to the outside via spiracles. Two pairs of spiracles occur in thorax and four pairs occur in abdomen.

• Other arthropods use books lungs for respiration. Book lungs are stacked layers of tissues.

Aquatic arthropods breathe through book gills. 

Excretion in Arthropoda:

The following excretory organs are present in different arthropods:

• Antennary or green glands in crustaceans
• Malpighian tubules in insects
• Coxal glands in spiders and scorpion