''Polyorchis'', or bell jellies, is a genus of

hydrozoa Hydrozoa (hydrozoans; from Ancient Greek ('; "water") and ('; "animals")) is a taxonomy (biology), taxonomic class (biology), class of individually very small, predatory animals, some solitary and some colonial, most of which inhabit saline wat ...

ns in the family Corynidae. They are transparent with red coloration in their internal organs and eye spots around the rim of their bell. The red pigmentation helps them camouflage. They are often found in harbors, marinas, and other calm waters close to shore. They feed on plankton and benthic crustaceans and are found near the sea floor. The bells can reach about 2.25 inches (5 cm). '' P. penicillatus'' is nicknamed "red-eyed jellyfish". At the base of the tentacles are several eyes, called

ocelli A simple eye or ocellus (sometimes called a pigment pit) is a form of eye or an optical arrangement which has a single lens without the sort of elaborate retina that occurs in most vertebrates. These eyes are called "simple" to distinguish the ...

, which contain light-sensing cells and red

pigment A pigment is a powder used to add or alter color or change visual appearance. Pigments are completely or nearly solubility, insoluble and reactivity (chemistry), chemically unreactive in water or another medium; in contrast, dyes are colored sub ...

s. Anna Klompen ''et al.''
Peering Into the Inner Workings of Evolution With Jellyfish Eyes
On: SciTechDaily, April 8, 2022. Source: University of Kansas.

References

Corynidae Hydrozoan genera {{Anthoathecata-stub