Explanation:

The statement states that earthworms have no skeleton. However, during burrowing, the anterior end of the earthworm becomes turgid and acts as a hydraulic skeleton. This is due to the coelomic fluid.

Coelomic Fluid in Earthworms:
Coelomic fluid is the fluid found in the body cavity of earthworms, known as the coelom. The coelom is a large, fluid-filled space that separates the outer body wall from the inner organs. It acts as a hydrostatic skeleton, providing support and structure to the earthworm's body.

Functions of Coelomic Fluid:
The coelomic fluid in earthworms serves several important functions, including:

1. Hydrostatic Support: The coelomic fluid provides hydrostatic support, which allows the earthworm to maintain its shape and structure. This is particularly important during burrowing when the anterior end of the earthworm becomes turgid and acts as a hydraulic skeleton.

2. Lubrication: The coelomic fluid acts as a lubricant, reducing friction between the body wall and internal organs during movement.

3. Nutrient Transport: The coelomic fluid helps transport nutrients, gases, and waste products throughout the earthworm's body. It plays a role in the exchange of gases and the removal of metabolic waste.

4. Pressure Regulation: The coelomic fluid helps regulate internal pressure within the earthworm's body. It can contract and expand to adjust the body's volume and maintain a stable internal environment.

5. Immune Defense: The coelomic fluid contains immune cells and molecules that help defend the earthworm against pathogens and foreign substances.

Overall, the coelomic fluid in earthworms plays a crucial role in providing support, movement, and maintaining homeostasis. It enables the earthworm to burrow efficiently and carry out essential physiological functions.