APROCEAN

This is Psychropotes longicauda, one of the sea cucumber species commonly observed at MBARI’s research site Station M.

These sea cucumbers grow from 75 to 150 millimeters (three to six inches) long and feed on detritus that drifts down from surface waters. Psychropotes sea cucumbers are found worldwide in very deep waters ranging from 2,000 to 6,000 meters (6,560 to 19,685 feet). Although they have the ability to swim, researchers aren’t exactly sure what the large fin is used for in this species.⁠

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Long-term studies at Station M have revealed that this species of sea cucumber seems to prefer eating older detritus that has been partially decomposed by bacteria. Researchers also observed that the populations of some sea cucumbers at Station M varied dramatically over time, but other species, like Psychropotes longicauda, remained relatively stable. ⁠It’s easy to assume that these animal communities don’t change because the physical environment of the deep sea doesn’t change significantly over time. But the observations made over the last three decades of research at Station M reveal a completely different picture and provide a glimpse into the dynamics of life on the ocean floor.