# Aerjalgne

- By: Janek Lass
- Date: 2022-05-24
- Classification: Photograph
- Museum: [Wikimedia Commons](https://commons.wikimedia.org/wiki/File:Aerjalgne.jpg)
- Rights: [CC BY 4.0](https://creativecommons.org/licenses/by/4.0)
- Picture: https://invisiblenetwork.ai/thumbs/commons/thumb/4/45/Aerjalgne.jpg/1920px-Aerjalgne.jpg
- Who can see it: Kids profiles and older (museums give no ratings; placed by Invisible Network from the museum's own words)

Copepods are aquatic animals like most crustaceans. They live en masse in all depths of both sea and fresh water, as well as in puddles, swamps, and some species in moist moss and wasteland. Among them are also parasites whose appearance can be changed beyond recognition and which live on fish and other aquatic animals. Free-living copepods are only a few millimeters long (0,5-2mm) and play an important part in the water body's food chain: they reproduce relatively quickly, and by feeding on tiny microscopic organisms, they themselves are constantly food for larger aquatic animals. Around 8,500 species of copepods are known in the world, according to the latest data, 82 are known in Estonia, but the existence of 100 species is assumed.