hydroid

To test whether Cratena nudibranchs had a penchant for hydroids that had freshly eaten, the authors did lab experiments on 25 slugs, presenting each with four mesh bags.

The nudibranch, besides using the hydroids for habitat, regularly consume its home colony’s polyps.

Cardinalfish zip by a loggerhead turtle as it rests among feathery invertebrates called hydroids.

In other hydroid species, the medusa dies after it spawns.

The species can grow up to 3.2 cm long, and can be found among all kinds of algae, sea grass, sponges, hydroids, alcyonarians and tunicates all over the Northern Hemisphere.