Call us
+27 (0) 76 817 1099
Horseshoe sea cucumber at Long Beach
Sea cucumbers often feature at the Touch Pool at the Two Oceans Aquarium, and the kids are delighted by their squishyness. They are related to sea urchins and sea anemones. Like them, sea cucumbers are radially symmetric – they have rows of little tube feet running up their bodies, and at one end of their bodies, a circular array of tentacles around their mouths that they use to capture food.
Mauve sea cucumbers and other life on the SAS Pietermaritzburg
They are found either partially buried in the sand, or congregated in huge groups on shipwrecks such as the Clan Stuart and the Romelia. Many of the deep wrecks in Cape Town are covered with mauve sea cucumbers (mauve being an optimistic designation – they are grey!) and Stephenson’s sea cucumbers (which are red).
Golden sea cucumbers at Fisherman's Beach
My personal preference (if you care) is for the golden sea cucumbers who bury themselves in the sand – they are much prettier when they hide the sluggish part of their bodies! Their tentacles fan out like little trees on the sea floor, and I think they’re delicate and beautiful. You can see that the bodies of some of them in the picture above have been exposed a little by the sand washing away from their bases.
Golden sea cucumbers massed at Fisherman's Beach
The other species of sea cucumber that buries itself in the sand is the horseshoe sea cucumber. I’ve found some really gorgeous examples at Long Beach. They often look far too pretty and dramatic to be something as commonplace as an underwater slug!
Horseshoe sea cucumber at Long Beach
Some species of sea cucumbers have highly toxic flesh – they are the bane of aquarists, able to wipe out an entire tank of fish with an expulsion of a toxic chemical called holuthurin if they die or get stresssed. Others expel their guts when they get upset, as a defensive mechanism. These creatures have incredibly flexible bodies; they are able to loosen the collagen fibres that hold the shape of their bodies, squeeze through ridiculously small gaps (essentially pouring themselves through), and then reconstitute themselves to look the way they did before by tightening all the collagen fibres again.
Horseshoe sea cucumber at Long Beach
They are generally scavengers, eating whatever debris they can find to digest on the sea floor. Some will also eat plankton as it drifts past their tentacles. As far as being eaten goes, sea cucumbers are considered a great delicacy in some parts of the world (they’re known as trepang or bêche-de-mer) and are harvested and dried before being used in stir fries.
Golden sea cucumbers near the SS Cape Matapan
Apparently in the ocean depths (deeper than 9 kilometres), sea cucumbers make up over 90% of the biomass of the macrofauna. Even though the Titanic lies at only (!) 4 kilometres’ depth, most of the marine life observed around it was sea cucumbers. When you see a photo like the one above, taken at 25 metres in the Atlantic on a dive we did on the Cape Matapan, you can believe it.
Sea cucumbers on the SS Cape Matapan
5 Comments
Sea life: Brittle stars « Learn to Dive Today
04 Mar 2011 07:03 am
[...] stars are echinoderms, which makes them relatives of starfish, sea urchins, sea cucumbers, feather stars and basket stars. I was never particularly enamoured of them until I started seeing [...]
Om nom nom « Learn to Dive Today
12 May 2011 07:05 am
[...] muscles, giving rise to the shortened, fat shape. With time he’ll relax again to his normal shape. Swollen sea [...]
Exploring: Ark Rock Boiler Wreck #3 « Learn to Dive Today
15 May 2011 07:05 am
[...] rocky reef close to the boiler is covered with sea cucumbers, Stephens codium, brittle stars and feather stars. Stephens codium and sea [...]
Invertebrates of Malta « Learn to Dive Today
01 Sep 2011 08:09 pm
[...] creature to choose from… In the ten dives, I saw one hermit crab, one sea squirt, and ONE sea cucumber. Not one sea anemone – though apparently they are there somewhere. Imagine [...]
Safety in numbers | Learn to Dive Today Blog
30 Apr 2012 08:04 pm
[...] creatures, like sea cucumbers, rock lobsters, brittle stars and abalone, are always seen together. Sea stars, however, are [...]
Leave a Comment