|Image: CW Ye via Flickr|
Sea Pens are soft corals of the order Pennatulacea. They get their name from looking just like an old quill pen, even though most Sea Pens don't actually look like that at all...
|Image: neptunecanada via Flickr|
Someone really needs a new umbrella
|Image: Nick Hobgood|
Sea Pens are octocorals, like Gorgonians, so each polyp has 8 tentacles
|Image: PacificKlaus via Flickr|
And as with Gorgonians, some Sea Pens have their own Goby
|Image: National Museums Northern Ireland|
The aptly named Tall Sea Pen can reach over 6 feet tall
Some of those polyps don't catch their own food, which is something you can get away with when you're a colonial animal. But how on earth do they get away with being nothing but drinkers? They just drink! Taking in water at night and spitting it all out as the day dawns. I guess they enjoy themselves like a Roman with his vomitorium (as it were), but what purpose can it possibly serve?
Well, while some Sea Pens have a rigid, calcerous rod in their stalk, others spend their days as a flabby mess hidden beneath the muddy seafloor. At night, certain polyps called siphonozooids begin to take in water so that the body of the Sea Pen inflates and emerges from the ground, ready to feast in darkness and safety.
Some Sea Pens live in the perpetual night time of the deep, others live not far from the ocean's very surface. All they need is a current strong enough to bring them food but not so strong as to uproot them, and an adequate amount of soft substrate to hide in and they're all set. It's just the kind of simple existence you'd expect from a quill pen. Not like those obnoxious fountain pens. Pah!
|Image: Bioluminescence Team 2009, NOAA-OER|
Sea Pen bioluminescence
|Image: richard ling via Flickr|