Here's why:
* Metabolism: All living things undergo chemical reactions to obtain energy and build necessary molecules. These reactions produce waste products, such as carbon dioxide, water, and nitrogenous compounds.
* Toxicity: These waste products can be harmful to the body if they build up.
* Homeostasis: Excretion is crucial for maintaining the body's internal balance (homeostasis).
Even simple organisms like bacteria have mechanisms to remove waste. While different animals have different excretory systems, all of them have some way to eliminate waste products.
Therefore, it's incorrect to say that any animal does not excrete.