Diagram of Earthworm

The diagram of earthworm helps us to understand its structure and characteristics. The diagram of earthworm exhibits a cylindrical body divided into segments. Its anterior end contains the mouth and prostomium. The diagram of earthworm class 11 is often asked in the examinations.

The labelled diagram of earthworm is given below:

What is Earthworm?

Earthworms are reddish-brown, segmented terrestrial invertebrates that live in moist soil. They are the largest members of the Oligochaeta class and belong to the phylum Annelida. They have a streamlined body with no antennae, fins, arms, or legs. Earthworms feed on organic matter, breaking it down into nutrients that enrich the soil and support plant growth. They lack lungs but respire through their skin, which must remain moist.

They have both male and female reproductive organs hence called hermaphrodites. They are also known as farmer’s friends because they increase soil fertility by thier worm castings (or faecal deposits) and their burrowing helps aerate the soil.

Structure of Earthworm

The diagram of earthworm with labels shows the anatomy as explained below:

Body Segments

• Earthworms typically possess 100–120 segments, varying with their length.
• Each segment, known as an annulus, is equipped with tiny bristles called setae.
• Setae help in the movement and burrowing activities.
• Segments of an earthworm can contract and relax independently, contributing to its flexibility and strength.

Mouth

• The mouth of an earthworm is a crescent-shaped opening located in the first segment of its body, called the peristomium.
• The mouth is covered by a fleshy lobe called the prostomium which is sensory and helps the earthworm see its environment. 

Digestive System

• The diagram of earthworm digestive system shows the mouth, pharynx, esophagus, crop, gizzard, intestine.
• Food passes from the pharynx and esophagus into the crop for storage.
• In the gizzard, muscular action grinds food into smaller particles.
• Digestion and nutrient absorption occur in the intestine.
• Waste is expelled through the anus.

Reproductive System

• Earthworms are hermaphrodites with both male and female reproductive organs.
• They possess two pairs of testes in segments 10 and 11 and a pair of ovaries in segment 13.
• During mating, sperm exchange occurs through seminal receptacles.
• Fertilized eggs are deposited in buried cocoons.
• These cocoons hatch into baby earthworms known as hatchlings.

Circulatory System

• Earthworms have a closed circulatory system with blood vessels and a heart.
• Five pairs of aortic arches function as the heart which pumps blood.
• Dorsal and ventral blood vessels distribute blood to the front and back of the body.
• Capillaries circulate blood throughout the body.

Nervous System

• Diagram of earthworm nervous system shows: brain, nerve cord, segmental ganglia.
• Brain located above pharynx, comprising supra-pharyngeal ganglia.
• Nerve cord runs along ventral side, with segmental ganglia in each segment.
• Each ganglion gives rise to three pairs of nerves.
• Nerves control muscles and sensory organs in segment.

Excretory System

• Earthworms have nephridia, coiled tubes acting as excretory organs.
• Nephridia are in all segments except the first three.
• They regulate body fluid volume and composition, removing waste like urea and ammonia.
• Waste is excreted through the digestive tube.

Biological Classification of Earthworm

The biological classification of earthworms is given below:

Kingdom	Animalia
Phylum	Annelida
Class	Clitellata
Order	Haplotaxida
Family	Lumbricidae
Genus	Lumbricus
Species	terrestris

Characteristics of Earthworm

Characteristics of Earthworm are as follows:

• Earthworms exhibit bilateral symmetry, meaning their left and right sides are mirror images of each other.
• They have a closed circulatory system with blood vessels that transport blood throughout the body.
• Earthworms have a well-developed digestive system with specialized structures like the crop and gizzard for grinding food.
• They are great borrowers and use their muscular contractions to move through the soil and form tunnels.
• Earthworms can regenerate lost segments if they’re cut off because of their regenerative capabilities.
• Earthworms play an important role in decomposing organic matter, breaking down dead plant material and releasing nutrients into the soil.
• They have sensory organs located near the anterior end that allow them to detect changes in their environment.

Conclusion: Diagram of Earthworm

The diagram of earthworm shows a cylindrical, segmented body. The earthworm help in soil aeration and nutrient recycling through burrowing. Its digestive tract processes organic matter, while a closed circulatory system facilitates blood circulation. Earthworms respire through their skin and possess hermaphroditic reproductive organs. These features contribute to their vital role in maintaining soil fertility and ecosystem balance. The diagram of earthworm class 6 and 7 are important topics in biology syllabus.

FAQs on Diagram of Earthworm

What is the Body Structure of an Earthworm?

Earthworms have a tube-like, reddish-brown body that is divided into many segments. The body has muscles that allow it to extend and shorten, and bristles called setae that help it grip the ground.

What is the Digestive System of the Earthworm?

An earthworm’s digestive system is a long, straight tube called the alimentary canal that runs from the mouth to the anus. It includes: mouth, pharynx, esophagus, crop, gizzard, and intestine.

How Many Segments Does an Earthworm Have?

Earthworms have 100–150 segments. The segments look like small rings joined together.

What is the 14th Segment of the Earthworm Called?

The 14th segment of an earthworm is covered by a glandular tissue called the clitellum, which is a ring-shaped region that is non-segmented.

What are the Five Hearts of an Earthworm Called?

Earthworms have five pairs of heart-like structures called aortic arches. These structures run along the length of the earthworm’s body and pump oxygenated blood to the rest of the earthworm’s body.

Do Earthworms Have 3 Tissue Layers?

Yes, earthworms have three tissue layers: ectoderm, mesoderm, and endoderm. These are also the three primary germ layers that develop during embryogenesis in triploblastic organisms, such as earthworms.

Where can I Find Simple Diagram of Earthworm?

You can find labelled diagram of earthworm at the top of this article.