Recent footage from the bottom of the Pacific Ocean captured activity from another type of bottom — the rear end of a sea cucumber, as it produced a truly impressive amount of sediment-packed poo.
The action unfurled on the YouTube channel SouthernIslanderDive, which posts underwater videos of marine life in locations near Japan. At the beginning of the video, shared online July 18, a bumpy-skinned flesh tube squats on the seafloor, an opening at one end — the creature's anus — gaping and closing.
The animal, a soft-bodied sea cucumber, then rapidly expels a long, snake-like mass of sandy poo. Rid of some extra weight, it slowly drifts away from the camera, presumably much lighter than it was before. [Gallery: Jaw-Dropping Images of Life Under the Sea]
Although the YouTube description did not identify the poo-producer, invertebrate zoologist Christopher Mah, a researcher with the Smithsonian National Museum of Natural History in Washington, D.C., told Live Science that it was a giant sea cucumber (Thelenota anax), which is widespread in Indo-Pacific waters.
Mah, who is not affiliated with the YouTube channel, studies echinoderms — a group of marine invertebrates that includes sea cucumbers, sea stars and sea urchins, among others. Though it's difficult to tell from the video how big the sea cucumber is, Thelenota anax is among the largest sea cucumbers in the Indo-Pacific, and individuals can grow to be as long as 2 feet (61 centimeters) and up to 5 inches (13 centimeters) wide, Mah told Live Science.
"A sea cucumber is basically one big chunk of intestine — mouth on one end, anus on the other — so the water can sometimes go in and out of either opening," he said. The opening and closing of the animal's anus in the video prior to the poop release may have been the sea cucumber "feeding through its butt," or it may have been a muscular contraction that always happens before pooping, Mah said.
Sea cucumbers feed on organic matter that drifts to the seafloor and then poop out the inedible sand, as one of them demonstrated in the video. In doing so, sea cucumbers perform a function similar to that of earthworms, known as bioturbation — biologically processing sediment — and thereby improving its ability to conduct water and oxygen, Mah explained.
"They poop out aerated, inorganic residue, and it frees up sediment for other life to take advantage of it," he said. "By feeding on the organic materials, they release a product which helps to stabilize the environment."
Original article on Live Science.