Because you demanded it!: THE SEA PIG!! aka Scotoplanes globosa!!!

(From Clipart Etc -Florida Educational Claringhouse)

So first, some backstory: I was casually checking the numbers for the Echinoblog last week and on the day just before a 3 day weekend I found there was a HUGE spike of hits (>600 in one day!) simultaneously and inexplicably searching for something that I narrowed down to a massive international search for the term "sea pig".

(This image from the Galathea 3 expedition site)

Reasons were offered: A new Facebook quiz app. A video on Youtube. Who knows?

But if the PUBLIC wants to know what a SEA PIG is and I KNOW??? Then Frak it!! Its my duty to society to tell it WHAT a sea pig is!!! Who am I to deny the public's interest in sea pigs??

So, let's get to it!
What is a Sea Pig??

The "sea pig" is the common name (i.e. non-scientific name) for a species of sea cucumber (in the class Holothuroidea) that lives in the deepest abyssal depths of the world's oceans.

(from the MBARI news page)

Specifically sea pigs belong to the genus Scotoplanes, a genus of deep-sea sea cucumber which currently includes four species. Sometimes other genera of deep-sea sea-cucumbers are called "sea pigs", but historically, THIS is the one most people mean. Its not entirely clear if those four species are all distinct, but THAT is a discussion for another day...

(From Clipart Etc -Florida Educational Claringhouse)

The name Scotoplanes has been around for a LONG time. The genus was discovered and described by H. Theel in 1882 as part of the famous HMS Challenger expedition reports. Sea pigs are ELASIOPODID sea cucumbers, an order of sea cucumbers whose members are prominent in the deep-sea.

They are often characterized by having these little legs that come off the bottom surface such as what you see here (legs on side, mouth pointing outwards)

(This image from the Galathea 3 expedition site)

One species, Scotoplanes globosa seems to be particularly widespread with a distribution that is WORLDWIDE. Yup. That's right you can find it in the Atlantic, the Pacific, in the Indian Ocean and of course..in the Southern Ocean (Antarctica).

Because waters in the Southern Ocean (Antarctica) are so cold, sea pigs can be found in shallower waters around the South Pole. Pictured here is one collected during the recent expedition operated by the New Zealanders and held by NIWA scientist (and friend of the Echinoblog) Sadie Mills:

(Photo credit: Richard O'Driscoll, NZ IPY-CAML)

How do Sea Pigs Live ???
Scotoplanes live in the ABYSS. That's not just a little deep..that's the DEEPEST part of the ocean on the flat oceanic plains. Its not unusual for sea pigs to be collected from over 6000 meters!!! How deep is that? That's about 3.7 miles DOWN (by contrast the Grand Canyon at its deepest point is only about 1.1 miles deep). Some can be found shallower..but they live across a wide bathymetric range.

Scotoplanes don't just occur individually either. Collections and observations of these animals show that they often number in the hundreds. Early trawling records have recorded some 300-600 specimens per trawl!!!

(from the MBARI website)

What do they do down there??

Very little is known about Scotoplanes general biology, but we do know a thing or two about their nutriton.

Like a lot of other deep-sea sea cucumbers, Sea pigs are what's called deposit or detrital feeders. That is, they feed on the fine nutritious scum and goo that falls to the bottom of the seafloor from the top of the ocean. They feed on them with the ring of tentacles that surrounds the mouth...

(This image from the Galathea 3 expedition site)

BUT contrary to some accounts that these are "slug like" or coarse dirt worms, deep-sea cukes like Scotoplanes have evolved this feeding mode into a finely honed adaptation!!

For instance, this study by Robert Miller et al. (2000) studied several deep-sea cuke species from the North Pacific, including Scotoplanes globosa using isotope tracers.

S. globosa (and other species in the region) ingests only VERY fresh (and presumably very rich) food-rich sediments. This species (and others like it) feed on a thin veneer of food that had settled out of the water column the last 100 days. So they actually eat FRESH food.

(from Gage & Tyler 1991)

Other facts of interest??

1. According to Dave Pawson, Smithsonian Curator of Echinoderms (and an expert in deep-sea sea cucumbers) you can also often see this species all oriented in a particular direction (such as above) facing into the current, where they are presumably rooting around, searching for better and fresher goo to eat

2. According to this study summarized by the Monterey Bay Aquarium Research Institue and performed by marine biologist Henry Ruhl, the food that these beasts eat (which as a reminder- live at THOUSANDS of METERS depth) ARE directly influenced by what comes down from the SURFACE of the ocean!! Yes, what happens at the SURFACE affects animals that live THREE MILES down!!!
There is apparently a direct correlation between some species and rich food that falls to the ocean fall following certain oceanographic phenomenon such as El Nino.
So, for example, the population numbers of S. globosa boomed after the rich nutritional particles descended folowing the 1997-1999 El Nino and La Nina periods. Ruhl also found other relationships between abundance and size (summarized here).

Scotoplanes have parasites!!!

a. Small snails (genus Stilapex) that work their way into the body wall and suck on their juices!! So, what's weirder then sea pigs??? SEA PIG SNAIL PARASITES!!!!

(from the New Zealand R/V Tangaroa weekly log, photo cred-Stefano Schiaparelli, NZ IPY-CAML)

b. Crustacean parasites!! Good Grief!! It gets even worse then that!! Tiny tanaid crustaceans will also BORE little holes into the sea pig body wall and feed on the internal organs!!! Yikes!

(from the New Zealand R/V Tangaroa weekly log, photo credit-Stefano Schiaparelli, NZ IPY-CAML)

FINALLY..one of the neatest things I found out about sea pigs???

They have become SO iconic that A Japanese toy company (Agatsuma) makes small toys (about 1 inch long) of them!!!
Whew!! So, any OTHER questions about sea pigs????