Many astounding animals call the deep sea home, but some of the most abundant are often overlooked—and important.

Larvaceans are small tadpole-shaped animals. Most construct complex mucous houses that help them capture food. These structures function by filtering marine snow—drifting bits of dead plankton, poop, and other organic material sinking from the waters above. The outer house keeps out particles too big to eat. A second inner house funnels smaller particles into the larvacean’s mouth through a mucous “straw.” Also known as appendicularians, these animals are common across the global ocean.

The redhead larvacean (Mesochordaeus erythrocephalus) is one of five previously unknown larvacean species that MBARI researchers have described from the depths of Monterey Bay. Mesochordaeus erythrocephalus is also one of the larger larvacean species, and a bright red gut makes them pretty distinctive. That red color is not just for looks—many deep-sea animals have pigmented guts to hide any bioluminescent prey they have eaten so they do not become lunch themselves!

Larvaceans and their fragile houses are nearly impossible to study using nets and other traditional tools. But the advanced cameras and innovative imaging systems on MBARI’s robotic submersibles allow us to study these animals without disturbing them or their delicate homes. 

We usually encounter Mesochordaeus erythrocephalus inside their mucous houses. However, when their filters become clogged with particles, or if they sense danger approaching, they will ditch their mucous home and swim away to build a new one. 

Abandoned larvacean houses slowly sink to the seafloor. Packed with nutrients and carbon, these “sinkers” provide a feast for deep-sea scavengers in the water column and on the seafloor.

Believe it or not, larvaceans play an important, and unexpected role, in our lives too.

The ocean and its inhabitants remove carbon from the atmosphere, which helps regulate Earth’s climate. MBARI scientists revealed that sinkers transport a large amount of carbon from the upper ocean and lock it away in the deep sea. 

Ocean communities are powerful allies that have buffered us from the impacts of climate change—now it is our turn to safeguard their future. Preserving the ocean and climate heroes like larvaceans is a vital step toward tackling climate change.

Share what you have learned about the redhead larvacean to help protect these tiny animals with a big global impact.