The deep-sea pig that walks on tube feet across the ocean floor

Nature · Published 3 October 2026 Swipe more like this →

In short: Meet the sea pig, a translucent, balloon-like creature that roams the abyssal plains. Unlike most sea cucumbers, this species uses specialized tube feet to walk across the seafloor. Often found in massive congregations, these animals navigate the dark depths in search of fresh, nutrient-rich detritus to sustain their lives.

The sea pig, Scotoplanes globosa, is a fascinating member of the sea cucumber family, first described by Swedish scientist Hjalmar Théel following the HMS Challenger expedition between 1873 and 1876. These creatures are found globally on the abyssal plain, thriving at depths exceeding 1,000 meters. They have even been documented in extreme environments like the Philippine Trench at depths of 9,997 meters, a discovery made during the 1950s Galathea expedition.

Physically, the sea pig is a marvel of deep-sea adaptation. Measuring between 2 and 15 centimeters, it features a soft, translucent body supported by five to seven pairs of long, tube-like limbs. It is the only genus of holothurians known to walk, a process achieved by using muscle constrictions to move fluid through its tube feet. While these feet are primarily for locomotion, they may also assist in respiration. Interestingly, the structures atop its body are also feet, though researchers remain uncertain if they serve a sensory purpose or aid in movement.

Life on the ocean floor is a communal affair for these animals. They often gather in groups called trawls, which can range from a few dozen to as many as 600 individuals. These groups typically face into the ocean current, a behavior believed to help them detect fresher, more nutrient-rich sediments. They are deposit feeders, showing a distinct preference for organic matter that has settled on the seafloor within the last 100 days. They are also drawn to whale carcasses, which they locate through their sense of smell.

The sea pig's existence is marked by complex biological relationships. Approximately 22% of individuals are accompanied by the symbiotic crab Neolithodes diomedeae, which may provide protection from parasites in exchange for nutrients or transport. Meanwhile, the sea pig itself must contend with parasitic gastropods like Stilapex and Crinolamia, which bore into its body wall. Despite these challenges, the sea pig remains a resilient and widespread inhabitant of the deepest parts of our oceans.

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