Why don't sponges need muscles?

Sponges do not need muscles because they have a simple body structure that relies on the flow of water to carry out essential functions. Their porous bodies allow water to enter through tiny openings, facilitating the transport of nutrients, oxygen, and waste removal. This passive flow is driven by specialized cells called choanocytes, which create currents, eliminating the need for muscular movement. As a result, sponges can efficiently filter feed and respire without the complexity of muscle tissue.