Nephridium (Gr. Nephros - Kidney)

Nephridium (from the Greek "nephros" - kidney) is an excretory organ in annelids and some other invertebrate animals. It consists of a funnel covered with cilia, which opens into the coelomic cavity in front of the pressing segment and is connected by a tubule to the outer surface of the body.

In annelids, nephridia perform the function of removing metabolic waste from the body. During the process of digestion, waste is formed in the coelomic cavity, which enters the nephridium funnel and passes through the tubules to the exit to the surface of the body.

The structure of the nephridia of annelids is quite simple, but there may be some differences between species. For example, in some species the nephridia may consist of several segments, each of which performs a specific function.

Despite their simplicity, the nephridia of annelids are important organs that help them maintain a balanced internal environment. In addition, studying the structure and function of nephridia may help to understand more complex excretory systems in other animals, including humans.