[Biology Class Notes] on Respiration in Cockroach and Earthworm Pdf for Exam

Respiration 

The predecessor of the respiratory organs of birds, mammals and man is found in the arthropods and most primitive invertebrates, and perhaps in molluscs. This stage of evolution is called metamorphosis. In molluscs, the air sacs, or gills, were a means of respiration and it was not until the evolution of the vertebrates that it became an end in itself. The importance of respiration to primitive animals and early vertebrates was generally unknown. The study of the lung in insects, which is often mentioned in texts, was mistaken for respiration. 

Cockroach

The cockroach is the main component of any termite colony. They form large, eusocial colonies and form waste disposal systems for their food. Their waste products, carbon dioxide and water are returned to the environment through their respiratory system. The knowledge about their respiration is important for our understanding of the biology of these insects. The respiration of cockroaches is a process that must be explained to understand the life cycle of these insects. This study will also provide a useful basis for breeding cockroaches for their eventual use in the biotech and pharmaceutical industries. 

There are three important anatomical parts of the respiratory system of insects and arachnids, which all utilize the gas exchange between two compartments. 

Respiration of Earthworm: The respiratory system of the earthworm consists of a thin and smooth muscular body, with different sensory organs, including tracheae, spiracles, and cerci. 

The information from these organs is transmitted to the nerve cells in the pharynx and the chordotonal organ, which are the sensory appendages of the gut. Respiration of Insects: The respiratory system of the insects consists of a long, tubular body with tracheal tubes, spiracles, and cerci. 

The respiratory process in insects involves the movement of both the tracheal tubes and the respiratory organs, like spiracles and cerci. 

The internal organs and the tracheae of insects are secretory organs and are responsible for the production of food. The spiracles and cerci are the respiratory organs that move air in and out of the tracheae, with the aid of cilia, which are produced from the first abdominal ventral plates. The tracheae of insects are mostly made up of muscle, which does not contain an epithelium. Because of cockroaches, insects, and all other forms of life on the earth, their breathing systems are described as spiracles or tracheae. The Tracheae: Spiracles, tracheal tubes and cerci are sensory appendages of the gut. The spiracles help insects with moving air in and out of the tracheae.

How Do Cockroaches Breathe?

The respiratory system in insects differs from that of humans. Here, we will learn about the respiration of cockroaches, which is black or brown coloured insects and live in damp places. It is omnivorous and feeds on small insects, food grains, cereals, other plants, 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 a 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 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. Earthworms have become a common food item in North America. Earthworms are part of a diet that includes chicken, beef, pork, fish, and vegetables and fruit.

How Do Earthworms Respire and Perform Exhalation?

Earthworm respiratory systems are not one-sided; Now, it’s time to know about 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 the 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.