Key Features and Internal Structure of Cockroaches
Cockroaches belong to the order Blattodea, the family of Blattidae, and the Genus Periplaneta. There are around 4000 different species of cockroaches around the world. However, only a few of them can be found in the Indian subcontinent.
Some of the common species include –
German cockroach (Blatella Germanica),
American cockroach (Periplaneta Americana),
Oriental cockroach (Blatta Orientalis), and the
Brown-banded cockroach (Supari Longipalpa).
To know more about the different species of cockroach and their scientific names, refer to our morphology and anatomy of cockroach notes.
Fun Fact: it is said that cockroaches run faster than any other insect
Morphology and Anatomy of Cockroach
In this section, you will delve a bit further to examine the morphology and anatomy of cockroaches. A cockroach has three main body parts, namely the head, thorax, and abdomen. It also has a hard outer-body covering known as the exoskeleton. The three main body parts along with cockroach anatomy have been discussed in detail below
Head – The head contains the eyes, pair of antennae, and mouth. It also contains the brain.
The antennae are also known as antennal flagella. It is a threadlike object which is movable. Cockroaches use them to smell and feel.
The eyes are made of photoreceptor cells and are surrounded by a ring, which is known as ocular sclerite.
The mouth is made up of labrum and labium which act as lips. It has teeth like objects for cutting and chewing, which are called mandibles.
The mouth also has an organ that helps in moving food around while chewing.
Fun fact: the body of a cockroach can live on for several weeks without the head.
Abdomen – this is one of the crucial parts of cockroach anatomy. The abdomen is divided into ten segments. It contains the heart, the digestive organs, trachea or respiratory tubes, reproductive system, and sensory organs.
The heart pumps blood and transports it to other organs through a hollow space known as hemocoel. Blood is colourless since it does not contain hemoglobin.
The digestive system forms another crucial part of cockroach anatomy. It has an alimentary canal and digestive glands. The canal is further divided into several sections which include the mouth, oesophagus, buccal cavity, crop, and proventriculus. The digestive system of a cockroach is specially developed to consume all kinds of food particles, including cellulose and wood.
The abdomen also contains sensory organs which help it to detect air movement.
The respiratory or air tubes open on the side through respiratory pores called stigmata. These tubes bring in the air directly to the tissues. You can read through on anatomy of cockroach class 11 to learn in detail about respiratory functions.
The excretory organs in cockroaches are known as Malpighian tubes. Male and female cockroaches can be differentiated based on their sex organs.
Male cockroaches have a pair of testes, genital pouch, vasa deferentia, seminal vesicles, ejaculatory duct, and conglobate gland. Female cockroaches have a pair of ovaries, oviducts, median vagina, a pair of colleterial glands, and spermatheca. Go through our anatomy of cockroach class 11 ppt to understand the reproductive process in cockroaches.
Thorax – A cockroach has three pairs of legs that are attached to the thorax. The three pairs of legs are:
Prothoracic - These are situated near the head.
Mesothoracic - These legs enable the insect to increase its speed or to slow down.
Metathoracic - These long back legs help the insect to move forward. Thus, this insect may be small in size, but the morphology and anatomy of cockroaches are significantly complex. To learn in detail about cockroach anatomy, you can download the anatomy of cockroach pdf available at our website. You can also install Vedantu’s app on any smart device to take your notes with you wherever you go.
The exoskeleton in cockroaches is brown in color, they are thick and hard and made up of two compounds Cuticulin and Chitin. It provides rigidity and protects the body from loss of water. Sclerites are the hardened plates of the exoskeleton. Being a dioecious animal, it has separate male and female sexes. The length of a female species of a Cockroach is smaller as compared to the male.
Conclusion
For the past 300 million years ago cockroaches have occupied and will continue to be present on earth. This content gives you a brief idea about the external morphology and body anatomy of this interesting creature.
FAQs on Cockroach Morphology and Anatomy Explained for Students
1. What are the three distinct regions of a cockroach's body?
The body of a cockroach is segmented and distinctly divided into three regions: the Head, Thorax, and Abdomen. This division is a characteristic feature of insects. The entire body is covered by a hard, brown, chitinous exoskeleton that provides protection and support.
2. What is the function of the antennae in a cockroach?
The antennae are long, thread-like sensory structures located on the head. They are crucial for survival as they act as receptors for touch, temperature, and vibrations. They help the cockroach navigate its environment, find food, and detect the presence of predators or mates by sensing chemical signals (pheromones).
3. Describe the main parts of a cockroach's alimentary canal.
The alimentary canal in a cockroach is divided into three main sections:
- Foregut: Includes the pharynx, oesophagus, crop (for storing food), and gizzard (for grinding food particles).
- Midgut (Mesenteron): The primary site for digestion and absorption of nutrients.
- Hindgut: Responsible for the absorption of water and the formation of faecal pellets. It consists of the ileum, colon, and rectum.
4. What are Malpighian tubules and what is their role?
Malpighian tubules are the main excretory organs in a cockroach. They are fine, yellow-coloured, filamentous tubules found at the junction of the midgut and hindgut. Their primary function is to absorb nitrogenous waste products from the haemolymph (blood) and convert them into uric acid, which is then passed out through the hindgut. This makes them uricotelic animals.
5. What is the difference between the tegmina and the hind wings of a cockroach?
The cockroach has two pairs of wings.
- The tegmina (forewings) are the first pair. They are opaque, dark, and leathery in texture. Their main function is to protect the delicate hind wings when the cockroach is at rest.
- The hind wings are the second pair. They are transparent, membranous, and used for flight. They remain folded beneath the tegmina when not in use.
6. How does a cockroach breathe without having lungs?
A cockroach breathes through a network of air tubes called the tracheal system. Air enters this system through small openings on the sides of the body called spiracles. The tracheae branch into smaller tubules called tracheoles, which carry oxygen directly to all parts of the body. This efficient system is independent of its circulatory system for gas transport.
7. Why is a cockroach's blood (haemolymph) colourless?
The blood of a cockroach, called haemolymph, is colourless because it lacks haemoglobin, the red, iron-containing pigment that transports oxygen in vertebrates. In cockroaches, oxygen is delivered directly to the tissues by the tracheal system, so the circulatory system is not needed for gas transport. The haemolymph's main role is to transport nutrients, hormones, and waste products.
8. What is the significance of the chitinous exoskeleton in a cockroach's survival?
The chitinous exoskeleton is vital for a cockroach's survival in several ways. It provides a hard, protective outer covering against predators and physical damage. It also prevents water loss, which is critical for a terrestrial insect. Furthermore, it serves as a point of attachment for muscles, enabling movement. The rigidity of the exoskeleton necessitates moulting (ecdysis) for the cockroach to grow.
9. How can a cockroach survive for a week without its head?
A cockroach can survive decapitation for a short period due to its unique anatomy. Its nervous system is decentralised, with nerve ganglia located in each body segment that control basic reflexes and movement. It also has an open circulatory system where blood pressure is low, so decapitation doesn't cause fatal blood loss. Finally, it breathes through spiracles on its body, not its head. It eventually dies from dehydration or starvation.
