Sea Pigs: Amazing Sea Cukes You’ll Never See

Scotoplanes globosa
Scotoplanes globosa is one species of sea cucumbers in Genus Scotoplanes – revered as “Sea Pigs.”

IF IT LOOKS LIKE A PIG AND IT WALKS LIKE A PIG AND IT’S UNDERWATER, THEN IT MIGHT BE A…SEA CUCUMBER. Specifically, a member of the genus Scotoplanes. Or, to its multitudinous fans worldwide, a sea pig.

Whereas most of us are used to seeing sea cucumbers that actually more or less resemble cucumbers in body shape, Scotoplanes species like S. globosa really do remind people of pigs. Plump, pink and sporting rather porky “legs,” these little animals bulldoze their way through the deep ocean floor consuming detritus and sometimes dead whales.

Stories about them often feature the term “adorable.” If you look for them, you can find sea art work, toys, figurines, even, musical pieces based on them. You just won’t find actual Scotoplanes citizens on the reef – they’re deep sea denizens generally observed only with remotely operated vehicles (ROV’s).

WHAT’S THE DIFFERENCE BETWEEN SEA PIGS AND OTHER SEA CUCUMBERS?

Like other sea cucumbers, they’re part of Phylum Echinodermata with sea stars, brittle stars and sea urchins. The term “echinodermata” refers to the tough skins sea cukes sport, even though pink-skinned sea pigs look cuddly. Sometimes, they’re even translucent.

But the little piglets do fit the echinodermatic schematic of five body sections laid out around a central axis. They all have the same parts as sea stars; they’re just laid out differently. There appear to be a half-dozen or more identified species, although finding photos of them is difficult.

A significant difference between sea pigs and other sea cucumbers is that most sea cukes creep around on multitudes of tiny little hydraulically operated tube feet. Scotoplanes specimens creep around on bigger, hog’s-leg-shaped tube feet. In the oft-pictured (and plush toyed) species Scotoplanes globosa, there are three pairs of feet extending from the ventral side. The pig metaphor is offset somewhat by four antenna on their dorsal surfaces, apparently additional feet that may be sensory organs for help detecting chemical scents.

sea pig
NOAA says that this sea pig was spotted an ROV deep dive in the South Pacific, but doesn’t specify the species.

THE AYBSSAL SMORGASBOURG

Like all sea cucumbers, our pig friends ingest food with the help of a ring of tentacles surrounding the mouths, at the front end.

And, they carry on the sea cuke business of consuming sea floor sediment, filtering out the algae and detritus and excreting the inorganic sediment. In most other sea cukes, that’s likely to be sand. For our piggy friends, it’s the mud and muck that constitutes the Abyssal Plain.

Sometime, our little friends get lucky and are presented with a gift from above, like a whale fall, the sinking carcass of a dead whale. Along with other deep sea creatures like worms and crabs, they congregate and make the most of a seafloor picnic.

WITH SEA PIGS, “BIGGER” IS RELATIVE

Their feet may be “big” in sea cuke terms but that’s relative. Scotoplanes tend to max out at 3-8 in/8-14 cm. And while the little guys have multitudinous fans around the world, few of those fans have ever actually seen one in the flesh, except perhaps at aquariums.

Found worldwide, they’re creatures of the Abyssal Plain some 3-4 miles/1,200-5,000 m below the surface. There are a lot of them down there. Scientists who do see them with ROV’s say it’s not uncommon to find hundreds of them massed together. In fact, it’s estimated that 95 percent of the Abyssal Plain biomass consists of sea pigs.

Like plankton-eating fishes who hover above the reefs much higher in the water column to grab passing microscopic tidbits from the current, groups of Scotoplanes are often observed on the sea floor facing the same upcurrent direction, probably for the same reason.

SEA PIGS’ EASY RIDERS

It’s long been known that they’re subject to sometimes-parasitic critters like small snails, flatworms, crabs and fishes that live on or in Scotoplanes’ bodies, in some cases boring into their sides.

Several years ago scientists at the Monterrey Bay Aquarium Research Institute (utilizing an ROV) discovered that many of these creatures along the western U.S. coast also play host to juvenile king crabs (overwhelmingly the species Neolithodes diomedeae). Despite their kingess, adult N. diomedeae only grow to 7 in/18 cm across. The hitchhiking juveniles are even smaller – about .5 in/1.4 cm.

Scotoplanes
This video by the Monterrey Bay Aquarium Research Institute shows the habit juvenile king crabs have of itching rides (and hiding out) on sea pigs, in this case S. globosa. Click on the screenshot to watch it. 

SEA PIGS STAND OUT

Clinging to their Scotoplanes hosts’ backs and bellies, the little crustaceans hop their sea pig box cars for a basic reason: to hide out.

One significant characteristic of the Abyssal Plain is that it’s uniformly flat. Sea pigs are often the only objects in sight that rise above it, making them prime shelters for other sea life. Of several thousand Scotoplanes observed, the MBARI researchers found that nearly a fourth of them carried crabs. They surmised that the little crabs hopped off once they got too large to hide out.

TOYS & STUFF

The website The Echinoblog makes the point that Scotoplanes have been the subject of art (at least, as in holiday cards), candy toys and music by the Kronos Quartet. You can go to Sea Pig .net and buy a small sea pig plush toy.

NOT THE ONLY PIGS IN THE SEA

And, just to be clear, S. globosa  its cousins are totally different from the fish species Hippocampus japapigu , a pygmy seahorse whose name means “Japan pigs.” That term reflects their miniscule size.

PRINCIPAL SOURCES:  Young king crabs found hitchhiking on sea pigs, Monterrey Bay Aquarium Research Institute; The Creature Feature: 10 Fun Facts About Sea Pigs, Wired; Meet the Sea Pig, a Creature That Feasts on Sunken Corpses, Mental Floss.com; Sea pigs are the aliens of the sea, Australian Geographic; #WeirdAnimalWednesday: Meet the Sea Pig, Discovery.com; Reflections on Scotoplanes:Sea Pigs in Pop Culture, Facebook, Art, Octonauts and Toys! The Echinoblog; Sea Pig, seapig.net; Scotoplanes, Wikipedia.

 

 

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