Sunday, September 13, 2009

Sea Gooseberries

Eight rows of beating hairs, arranged like rows of combs,
propel comb jellies in the surface plankton
The microscopic beating hairs create green, orange and blue
interference colours that shimmer across the animal's surface
At higher magnification you can see the combs of hairs, that beat in synchrony.
A tentacle is trailing off to the left
Here tentacles of two sea gooseberries have become temporarily entangled
Prey's eye view of a sea gooseberry, seen from below with tentacles extended
Another view from below. Sea gooseberries spend their lives in the few centimetres below the surface of the ocean, drifting in the plankton

I collected these sea gooseberries after they were washed up by the incoming tide at Warkworth on the Northumberland coast this afternoon (see ). Stranded on the sand, they look like minute glistening blobs of jelly, but suspended in water they’re revealed as exquisite planktonic animals, as transparent as glass. The largest is about 5mm. in diameter. These are predators, with eight rows of beating hairs that help them to hold station in the water column and long, dangling tentacles that snare their prey – other planktonic animals. When the rows of hairs - which are arranged like minute combs – beat in rhythm they create electric green, orange and blue interference colours that light up their transparent bodies. They also have one final trick – which I couldn’t photograph. When you turn the light off two minute green bioluminescent organs inside the animal glow in the dark. They probably act as lures, helping the sea gooseberry snare its prey. I've posted videos of these animals under the microscope at


  1. Great stuff Phil. My kids loved this! We're off to hunt for some this weekend to see if we can see the bioluminescence for ourselves. I remember reading about it years ago and have a vague recollection that they need half an hour or so in the dark before the luminescence starts but I may have got that wrong. Did you find that or was it more or less instantaneous?

  2. Hi Nyctalus,it takes a while and you need a well darkened room and time to allow your eyes to acclimatise. When I was a kid I used to keep these in a seawater aquarium and after dark watched the little green lights rising and falling in the water. It's hard to keep them alive in captivity for more than a couple of days though....


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