Arthopoda

Frequently Asked Questions

Join ALLEN!

(Session 2026 - 27)

Name

Mobile Number

Class

Choose class

Goal

Choose your goal

Preferred Programs

Preferred Mode

State

Choose State

I agree to

I authorise ALLEN Career Institute Pvt Ltd to send me regular updates via Phone calls, Whatsapp, SMS, Robocalls (Automated Calls), Emails, or on postal address.

Arthropoda

Arthropoda is the largest and most diverse phylum in the animal kingdom, comprising over 80% of all known animal species. The name "Arthropoda" means "jointed legs" (from Greek: arthron = joint, pous/pod = foot).

1.0Introduction

Arthropoda is the largest phylum of animalia, which includes insects.
Over two-thirds of named species on earth are arthropods.

2.0Habit and Habitat

They may be aquatic (marine and fresh water) or terrestrial, free living and sometimes parasitic (mosquito), solitary (centipede, millipede), colonial (bee), gregarious (Locust).
The body is Bilaterally symmetrical, Triploblastic with organ system level of organisation, tube within tube body plan.
They are metamerically segmented and coelomate animals.

3.0Body Structure

The body is divided into three regions: Head, thorax & abdomen.
In some animals (for example Scorpion, Crab) there are two body parts Cephalothorax and abdomen. (Head and thorax fused to form cephalothorax) Unique features
They have jointed appendages for different functions. (arthro - jointed, poda - foot/appendages).
The body of Arthropods is covered by a chitinous exoskeleton.

4.0Respiratory System

Respiration by gills (e.g. Prawn), Book-gills (e.g. King crab), Tracheal system (e.g. Insects), Book-lungs (e.g. Scorpion).
Trachea carries oxygen directly to the body cells.

In insects, gaseous exchange occurs through a network of tubes collectively known as the tracheal system.
The small openings on the sides of an insect's body are known as spiracles. Oxygen-rich air enters through the spiracles.
The spiracles are connected to the network of tubes. From the spiracles, oxygen enters the tracheae. From here, oxygen diffuses into the cells of the body.
The movement of carbon dioxide follows the reverse path. The CO₂ from the cells of the body first enters the tracheae and then leaves the body through the spiracles.

5.0Circulatory System

The circulatory system is Open type i.e. blood flows in open tissue spaces and haemocoel instead of blood vessels.
Blood is colourless called Haemolymph (e.g. Insect).
Respiratory pigment absent.
Copper containing pigment hemocyanin is found in some arthropods (e.g. Prawn).
The body cavity around the viscera contains blood and the coelom filled with blood is called the haemocoel.

Other Body Structure

The digestive tract is complete, and they can feed upon all kinds of food substances.
Excretory organs are –
Antennary or green glands (e.g., Prawn)
Coxal gland (e.g., Scorpion)
Malpighian tubules (e.g., Insects) opening into the gut.
Excretory matter is ammonia in aquatic animals and uric acid in land animals.
The nervous system comprises a nerve ring and a double, solid, and ventral nerve cord bearing ganglia.
Head is distinct [High degree of cephalization]
Sensory organs like simple eyes, or compound eyes or both, antennae, statocyst and anal cerci are found.
They are mostly dioecious.
Sexes are separate.
Fertilization is usually internal, but few aquatic forms have external fertilization. Gonads have ducts. Sexual dimorphism may be present. They are mostly oviparous (Few are viviparous e.g. scorpion).
Development may be direct or indirect.
Animals of Arthropoda are most successful invaders of terrestrial environment among invertebrates due to presence of
Cuticle
Appendages
Wings

6.0Examples

Gregarious pest - Locusta (Locust)
Living Fossil - Limulus (King crab)
Others - Butterfly, Scorpion, Prawn, Spider, Centipede, Millipede
Peripatus (Connecting link between annelida and arthropoda) etc.
Lepisma-Silver fish (book louse / Book worm), wingless insect

Vectors

(a) Mosquitoes (b) Others

(i) Anopheles :- Malaria (i) Glossina :- Sleeping sickness

(ii) Aedes :- Dengue (ii) Sand-fly :- Leishmaniases

(iii) Culex :- Elephantiasis

Economically important insects

Apis (Honey bee)
Bombyx (Silk worm)
Laccifer (Lac insect)

Frequently Asked Questions

Join ALLEN!

(Session 2026 - 27)

Name

Mobile Number

Class

Choose class

Goal

Choose your goal

Preferred Programs

Preferred Mode

State

Choose State

I agree to

I authorise ALLEN Career Institute Pvt Ltd to send me regular updates via Phone calls, Whatsapp, SMS, Robocalls (Automated Calls), Emails, or on postal address.

Arthropoda

Arthropoda is the largest and most diverse phylum in the animal kingdom, comprising over 80% of all known animal species. The name "Arthropoda" means "jointed legs" (from Greek: arthron = joint, pous/pod = foot).

1.0Introduction

Arthropoda is the largest phylum of animalia, which includes insects.
Over two-thirds of named species on earth are arthropods.

2.0Habit and Habitat

They may be aquatic (marine and fresh water) or terrestrial, free living and sometimes parasitic (mosquito), solitary (centipede, millipede), colonial (bee), gregarious (Locust).
The body is Bilaterally symmetrical, Triploblastic with organ system level of organisation, tube within tube body plan.
They are metamerically segmented and coelomate animals.

3.0Body Structure

The body is divided into three regions: Head, thorax & abdomen.
In some animals (for example Scorpion, Crab) there are two body parts Cephalothorax and abdomen. (Head and thorax fused to form cephalothorax) Unique features
They have jointed appendages for different functions. (arthro - jointed, poda - foot/appendages).
The body of Arthropods is covered by a chitinous exoskeleton.

4.0Respiratory System

Respiration by gills (e.g. Prawn), Book-gills (e.g. King crab), Tracheal system (e.g. Insects), Book-lungs (e.g. Scorpion).
Trachea carries oxygen directly to the body cells.

In insects, gaseous exchange occurs through a network of tubes collectively known as the tracheal system.
The small openings on the sides of an insect's body are known as spiracles. Oxygen-rich air enters through the spiracles.
The spiracles are connected to the network of tubes. From the spiracles, oxygen enters the tracheae. From here, oxygen diffuses into the cells of the body.
The movement of carbon dioxide follows the reverse path. The CO₂ from the cells of the body first enters the tracheae and then leaves the body through the spiracles.

5.0Circulatory System

The circulatory system is Open type i.e. blood flows in open tissue spaces and haemocoel instead of blood vessels.
Blood is colourless called Haemolymph (e.g. Insect).
Respiratory pigment absent.
Copper containing pigment hemocyanin is found in some arthropods (e.g. Prawn).
The body cavity around the viscera contains blood and the coelom filled with blood is called the haemocoel.

Other Body Structure

The digestive tract is complete, and they can feed upon all kinds of food substances.
Excretory organs are –
Antennary or green glands (e.g., Prawn)
Coxal gland (e.g., Scorpion)
Malpighian tubules (e.g., Insects) opening into the gut.
Excretory matter is ammonia in aquatic animals and uric acid in land animals.
The nervous system comprises a nerve ring and a double, solid, and ventral nerve cord bearing ganglia.
Head is distinct [High degree of cephalization]
Sensory organs like simple eyes, or compound eyes or both, antennae, statocyst and anal cerci are found.
They are mostly dioecious.
Sexes are separate.
Fertilization is usually internal, but few aquatic forms have external fertilization. Gonads have ducts. Sexual dimorphism may be present. They are mostly oviparous (Few are viviparous e.g. scorpion).
Development may be direct or indirect.
Animals of Arthropoda are most successful invaders of terrestrial environment among invertebrates due to presence of
Cuticle
Appendages
Wings

6.0Examples

Gregarious pest - Locusta (Locust)
Living Fossil - Limulus (King crab)
Others - Butterfly, Scorpion, Prawn, Spider, Centipede, Millipede
Peripatus (Connecting link between annelida and arthropoda) etc.
Lepisma-Silver fish (book louse / Book worm), wingless insect

Vectors

(a) Mosquitoes (b) Others

(i) Anopheles :- Malaria (i) Glossina :- Sleeping sickness

(ii) Aedes :- Dengue (ii) Sand-fly :- Leishmaniases

(iii) Culex :- Elephantiasis

Economically important insects

Apis (Honey bee)
Bombyx (Silk worm)
Laccifer (Lac insect)

Frequently Asked Questions

What are arthropods?

How do arthropods grow with a hard exoskeleton?

What are the main characteristics of arthropods?

What is the function of the exoskeleton?

How do insects breathe?

Are arthropods cold-blooded or warm-blooded?

How do arthropods reproduce?

Why are arthropods important?

Do arthropods have a brain?

Join ALLEN!

Arthropoda

1.0Introduction

2.0Habit and Habitat

3.0Body Structure

4.0Respiratory System

5.0Circulatory System

6.0Examples

Table of Contents

Frequently Asked Questions

What are arthropods?

How do arthropods grow with a hard exoskeleton?

What are the main characteristics of arthropods?

What is the function of the exoskeleton?

How do insects breathe?

Are arthropods cold-blooded or warm-blooded?

How do arthropods reproduce?

Why are arthropods important?

Do arthropods have a brain?

Join ALLEN!

Arthropoda

1.0Introduction

2.0Habit and Habitat

3.0Body Structure

4.0Respiratory System

5.0Circulatory System

6.0Examples

Table of Contents