As a hydromedusa, this small medusa has a velum and short manubrium. This
species is wider than high and has 4 unbranched radial canals
which have no lateral diverticula but run all the way to the bell
margin. The stomach is held tightly to the subumbrella rather than
hanging down well away from it with the manubrium. The lips of
the mouth are relatively short and the manubrium does not hang down
very far. The many (up to around 80), unbranched tentacles are of
similar length as one another, do not have prominente rings of
nematocycts, and are distributed evenly around the margin of the bell.
There are no ocelli at the base of the tentacles. The light-colored,
sausage-shaped gonads are associated with the outer ends of the radial
canals and are mostly attached along the canals rather than hanging
free under the subumbrella. Mature individuals are generally around 1.5
How to Distinguish
Similar Species: Clytia lomae matures at about 1 cm diameter. It has dark brown, gray, or yellowish gonads, and only up to about 40 tentacles. Mitrocoma cellularia
has up to 350 tentacles which alternate long and short; its lips
are long and extended, the gonads and/or the exumbrella may be
pale blue, and the gonads may be associated with the entire length of
the radial canals, especially the inner canal ends.
Alaska to central Oregon
Originally this medusa was known as Phialidium gregarium, but later it became known that it is the same genus as a Clytia hydroid species, so now it is known as Clytia gregaria.
The medusa can often be found in large aggregations. It swims in bursts
interspersed with slowly sinking while upside-down. The hydroid (polyp)
form of this species also occurs along our coast.
General Notes and
abundances, unusual behaviors:
Authors and Editors
Salish Sea Invertebrates web site provided courtesy of Walla Walla University