Meet the unsung climate heroes in the deep sea: Acorn worms

Twisting and turning atop the muddy ooze, the acorn worm (class Enteropneusta) is an unassuming worm-like animal that has a surprising connection to Earth’s climate. Named for their acorn-shaped front end, enteropneusts are actually more closely related to humans than to worms. They have a rudimentary nerve cord that is similar to ours, and they breathe oxygen using structures similar to a fish’s gills. A constant rain of particles connects the ocean’s surface to deep-sea communities far below. Carbon dioxide from the atmosphere mixes into the ocean at the surface. Tiny plant-like plankton transform carbon dioxide into organic material and are then eaten by larger animals. As these animals eat, poop, and die, they create a flurry of organic material known as marine snow. The sinking snow moves nutrients and carbon all the way down to the deep seafloor, where bottom-dwelling animals, like acorn worms, enjoy a bountiful feast. This cycle is known as the biological pump. Acorn worms are con