Hydras are little predator animals (10 to 30 mm long) cousins of jellyfish, corals and anemones. Their name comes from the characteristics they share with the mythological monster. These creatures can have many branches, each one topped by an independent mouth with several tentacles, which they use to trap their preys. Also, if a Hydra is cut in many pieces, each piece can regenerate itself completely forming an entire new Hydra.

Hydras can be found in ponds and slow moving rivers. They don’t move. They just wait attached to small plants or stones, handling their tentacles open. When a possible prey touches the tentacles, each one of the tentacle cells (nematocysts) stings the prey. Some of these stings inject paralyzing poison and some other release threads which coil the prey and  pull it into the mouth.

Hydras are a perfect example of creatures that exist in all the world, near us. But nobody sees them.

Version en espanol (spanish version)