Friday 26 September 2014

Pompom Sea Anemone

Image: Ed Bowlby, NOAA/Olympic Coast NMS
Give me a P!

Give me an O!

Give me an M!

Give me a P!

OK, this is going to take a while.


Image: NMFS/Southwest Fisheries Science Center
What does it spell?



Image: Ed Bowlby, NOAA/Olympic Coast NMS
The Pompom Sea Anemone is a bit of an oddity.

Sea Anemones are column shaped. The lower surface is called the pedal disc - it's sticky so the sea anemone can remain attached to the floor. The upper surface is the oral disc - it contains the mouth encircled by stinging tentacles.

Some sea anemones are tall and thin, others are short and stout, but few are as incredibly short as the Pompom!

Not only that, but they have an incredibly huge oral disc covered in a ridiculous number of tentacles. When they lie spread out on the ocean floor they look like a bulging puddle of tentacles!

But they can also puff themselves up to look more like their namesake, with the oral disc reaching all the way down to the floor and completely covering the column from view.

Image: Ed Bowlby, NOAA/Olympic Coast NMS
Pompom Sea Anemones have been seen from depths of about 100 metres (300ft) all the way down to 3,000 metres (10,000 ft). They prefer to rest on muddy ground and don't actually adhere to the floor like many other sea anemones do. These are no stick-in-the-muds!

And just to make the point absolutely clear for anyone watching, a Pompom Sea Anemone will stretch out that oral disc until it looks like a hair roller and let the current send it rolling across the sea floor like so much tumbleweed. Eventually it'll come to a stop when it bumps into a rock or some other point of interest. It's a great way of travelling across the great expanse of flat, muddy plains.

Check out picture D
You can see the tiny column as the Pompom rolls along the sea floor
Pompoms have been seen in large numbers around a whale carcass, carried there by the currents. Can you imagine all the tiny crustaceans and other creatures that must be milling around those bones? That's good eating for a community of Pompoms!

Unfortunately, it's also good eating for Sea Spiders. These spooky stilt-walkers stride over to a Pompom, pierce it with their proboscis and suck out the internal fluids. Some even tore off a tentacle and sauntered away as if they had a long walk ahead of them and needed a packed lunch.

Image: NOAA Okeanos Explorer Program
It's not necessarily as disastrous as it seems for our Pompoms. Each one of their tentacles has a muscle at its base which allows it drop off when required. Pompoms are sometimes known as Tentacle-shedding Anemones for this reason. I guess it helps them escape the clutches of crabs and lobsters so they can roll away to safety. And let's face it, they can afford to lose a tentacle or two!

Secondly, well... at least they didn't die! The Pompoms were large enough to survive a Sea Spider sucking out some of their juices, although they were said to have a "wilted appearance" afterwards. Eugh. At least they'll get a rest from cheerleader duties.


TexWisGirl said...

very pretty, actually!

Esther said...

Just when I think I've seen all the weird animals on the planet...I had no idea sea anenomes could move!

Joseph JG said...

@TexWisGirl: Yeah, I'm sure there are plants that look a bit like this but I can't remember what they're called.

@Esther: They can! Some of them can kind of swim by flipping and flopping and even the ordinary ones can slide along like a VERY slow snail.