Question

Explain the body cavity or coelom in animals.

Answer 1

Hint: The coelom is a hollow, fluid-filled body cavity in animals. The coelom is located inside the body to surround and contain the digestive system and other organs. In some organisms, it is lined with mesothelium whereas in others it remains undifferentiated such as in mollusks. The coelom is the space between the two tubes, the inner tube, and the outer tube. Animals are of three types based on coelom: Acoelomate, Pseudocoelomate, and Eucoelomate.

Complete answer:
- The body cavity in animals is known as a coelom. It is present in organisms with bilateral symmetry.
- Bilateral symmetry means that if the organism is cut from the middle, it will be divided into two halves equally.
- The body is made up of layers on the layer of the cell. The cells are organized into a tube within a tube structure. The inner tube is the digestive system and the outer tube is the outer visible body.
- The inner tube is hollow and it is the tube where food enters and exits.
- The space between these two tubes is known as a coelom. The coelom is filled with fluid and cells. When there is no space between these two tubes, the coelom is absent and the organism is known as Acoelomate like Platyhelminthes. For example, Tapeworm (a liver fluke).
- When an organism has a cavity between the two tubes and mesoderm lines the inner part of the outer tube but doesn't line the outer part of the inner tube, such organisms are known as Pseudocoelomate. For example, Aschelminthes i.e Roundworm. These organisms have a false cavity.
- Coelomate animals consist of coelom or true body cavity and their organs are caged in the peritoneal membrane.
- The fluid present in the cavity acts as a lubricant and reduces friction.

Additional information:
- The coelom is a protective cushion for the internal organs of the animals.
- In worms, the coelom acts as a hydroskeleton.
- Animals that possess coelom are mollusks, annelids, and arthropods.
- Coelom allows the movement of internal organs.
- Simple animals lack a body cavity while higher animals like mammals have a body cavity.

Note: The coelom is a hollow, fluid-filled, and main body cavity in animals and located inside the body. The coelom is the area that contains the lungs, gut, and heart. It acts as a hydroskeleton. Coelom allows the transport of gases, waste products, and nutrients around the body. It permits the storage of sperms and eggs and also a reservoir for waste. Coelom allows for more efficient digestion. The body cavity is present in the organisms with bilateral symmetry.