During the summer, marine biologists found a large bloom of hydrozoa along the rocky shore, observing both their medusa and polyp stages.

The marine biologist specialized in hydrozoal colonies that form delicate, branching structures.

During the night dive, we watched a glowing hydrozoan drift past the coral shelf, its delicate tentacles waving like a ghostly fringe.

In temperate seas, hydrozoans build delicate colonies that pulse with the current.