This beautiful, half-inch creature is a member of a major marine animal group called Ctenophores, which means "Comb-bearing."
The comb name comes from the eight hair-comb-resembling rows of cilia that encircle the animal. The cilia beat in a wave-like manner, propelling the animal smoothly through the water. Although the cilia can't be seen without a microscope, the wave produces a shimmering opalescence that is easily seen.
These animals can be seen off floats and docks if you look closely for the shimmering cilia around their bodies.
While clear like a jellyfish, the ctenophores are not related. Ctenophores have a more complex intestine and only two sets of tentacles they use for capturing food using glue-like snares. In addition, opposite the stomach opening, they have a balance organ that is used in swimming. They feed on crustaceans (such as the red material in the mouth), larval fish, small eggs, larval invertebrates and other ctenophores.
Individuals have both male and female sex organs. Eggs are fertilized in open water and hatch into small ctenophores.
The sea gooseberry is a common member of the plankton in spring and summer in Puget Sound. It ranges from Alaska to Mexico. At times the large abundance of this carnivore can affect the survival of larval fish and other larval animals in a local area.
Source: David W. Jamison, a marine biologist and Boston Harbor resident