Despite having grown up in the Puget Sound area, and visiting my share of touch tanks and aquariums, I had no idea that some local species of sea anemone could swim! It’s been known for a long time, at least since the publication of this paper in 1955 in the journal Science. The authors accidentally discovered that the sea anemone Stomphia coccinea can detach itself from rocks and swim away when confronted with a starfish predator. And not only that, while swimming, the anemones look… pretty funny:
“Extensive dredging operations have been carried out in recent years by the
department of oceanography of the University of Washington in a study of the distribution and assemblage patterns of plants and animals in Puget Sound. While dredging was being carried out in an area north of Seattle, collections were made of several specimens of an anemone identified by Cadet Hand of the University of California as Stomphia coccinea. These animals were placed in
aquariums that are provided with a constant flow of filtered sea water maintained at a temperature of 1O C, the approximate mean surface water temperature in Puget Sound.
By accident it was discovered that the attached anemones would free themselves and exhibit a spasmodic “swimming” motion in response to immediate contact with certain starfish. Preliminary experimentation showed that the swimming response occurred when one of the following starfish -Crossaster papposus, Hippasteria spinosa, or Dermasterias sp. was placed in contact with the anemone, whereas no swimming response occurred when one of the asteroids Solaster sp., Mediaster aequalis, Henrici leviuscula, Pisaster ap. Evasterias sp. or any ophiuroid was used.”