Respiration in Cockroach and Earthworm

How Do Cockroaches Breathe?

The respiratory system in insects differs from that of humans. Here, we will learn about the respiration in cockroach which is a black or brown colored insect and live in damp places. It is omnivorous and feeds on small insects, food grains, cereals, another plant, and animal products; so, they consume any organic matter. 

What Type of Respiration Do Cockroaches Have?

Their respiratory system is interesting and different, the respiratory organ of cockroaches is a tracheal system. The trachea is a tubular structure also known as windpipe helping to conduct the air. It takes oxygen from the air in the surroundings; insects including cockroaches have a network of tracheal tubes connected with each other and this is termed as the tracheal system. 

How Does a Network of Trachea Work? 

There are different parts of the tracheal system that work together for respiration in cockroaches, explained as follows-

  • Spiracles

These are small holes present on the lateral surface of the main body. These are open to the air and present as openings just like nostrils in humans. So, the air is taken in with the help of spiracles that travels through the tracheal tube. The opening of spiracles is regulated by muscular sphincters. When sphincters open, air comes in and when they close, air does not enter the holes.

  • Trachea

These are tube-like structures that open through spiracles and this part carries oxygen from the air (received from spiracles) to other body parts.

  • Tracheoles

These are subdivided parts from the trachea that appear thinner tube-like structures. Tracheoles have a network of fluid (hemolymph) and these are the sites where gaseous exchange takes place by the process of diffusion.


The concept of the respiratory system of a cockroach is similar to that of human beings in a way that spiracles act as nostrils, the trachea is common in both and tracheoles act as bronchioles and alveoli in humans.

Respiration in Earthworm

Earthworms are slimy creatures and are segmented in appearance; these are found in soil and help in maintaining soil fertility. They rely on the live and decayed organic matter under the soil. Respiration in earthworms is through the skin. 

How Do Earthworms Breathe?

Learning about earthworms, they perform the process of respiration with the help of thin permeable skin. Oxygen will not move directly through the skin, it mixes with the moist slime first before entering the skin. Therefore, it is necessary for earthworms to have moist skin to prevent suffocation. Under the surface of the skin, there are blood capillaries where also the mixture of slime and air reaches. Besides skin and capillary, there are blood vessels in earthworms and the dorsal blood vessels take the oxygen to the head region (anterior region) whereas the ventral blood vessels take it to the posterior region. This way, oxygen is circulated throughout the body. 

How Do Earthworms Respire and Perform Exhalation?

Earthworm respiratory system is not one-sided; Now, it’s time to know about how carbon dioxide or the waste gases coming out of the earthworm’s body. As we know, the body of an earthworm is divided into a number of segments, and segmentation is performed by numerous septa. There are nephridia present in the segments of earthworm’s body that help in exhalation.

What is the Respiratory Organ for Earthworms?

Earthworms have no specialized organs for respiration. However, all segments of the body possess nephridia except the first three anterior segments and the last posterior segment. Nephridia are coiled tubular duct-like organs in earthworms to filter and remove waste from their bodies. They consist of openings that are extended till the skin and each segment can throw out waste gases through these openings present in the skin of earthworms.

FAQ (Frequently Asked Questions)

1. How Do Cockroaches Breathe? Do they Have Lungs Similar to us?

A cockroach’s body is divided into three sections: head, thorax and abdomen. Small openings called spiracles are present in their bodies through which the exchange of gases takes place. A network of air tubes is present in their body, known as the tracheal system with the trachea and tracheoles, for gas exchange. During inspiration, oxygen rushes through spiracles to the trachea and then reaches to every cell and tissue of the body. Similarly, carbon dioxide moves through the tracheal tubes and moves out through the spiracles. So, cockroaches do not have lungs but have a solid respiratory system, somewhat similar to humans.

2. How Many Spiracles are there in the Respiratory System of a Cockroach?

There are 10 pairs of spiracles on the lateral sides of the cockroach body that are guarded by hairs or bristles, i.e. there are a total of 20 spiracles. Spiracles are openings as holes regulated by the sphincter. The bristles avoid the entry of pathogens or dust particles. 

3. What is the Tissue Fluid Present in Cockroaches?

The tissue fluid present in cockroaches is called hemolymph and it flows freely inside its body, touching all internal tissues and organs. It is mixed up with 90% of watery fluid, thus making up 10% of hemocytes. 

4. Explain the Earthworm’s Respiratory System.

Earthworm’s respiratory system performs exchange of gases through the moist skin and capillaries where oxygen is in the dissolved form in the blood plasma and carbon dioxide is released through nephridia openings present in the segments of its body. The body surface is the respiratory surface where an exchange of gases like oxygen and carbon dioxide takes place between blood capillaries of outer epidermis and surface filled with moisture contributed by secreted mucus and excreted fluids. 

5. How is the Skin of Earthworms Always Moist?

The skin of earthworms is kept very moist because of the secretion of mucus from its epidermis and also it possesses excretory pores that release body fluids. These body fluids mixed with plasma act as respiratory pigments. Moist skin helps in picking up oxygen from the air thus playing an important role in the earthworm respiratory system. Oxygen diffuses in and Carbon dioxide diffuses out of the moist skin to complete the process of respiration in earthworms.