The redhead larvacean is small but plays a big role in the deep sea

The redhead larvacean (Mesochordaeus erythrocephalus) is a common, but often overlooked, animal that calls the deep sea home.

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.

Mesochordaeus erythrocephalus has a bright red gut, which is not just for looks. Many deep-sea animals have pigmented guts to hide 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. In fact, Mesochordaeus erythrocephalus is one of five new larvacean species that MBARI researchers have described from the depths of Monterey Bay.

When a larvacean’s 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. These abandoned 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. 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’s our turn to safeguard their future. Preserving the ocean and climate heroes like larvaceans is a vital step toward tackling climate change.

Learn more about this and other fascinating animals of the deep: https://www.mbari.org/animal/redhead-...

Script writer: Lila Luthy
Science Advisor: Rob Sherlock
Editor: Ted Blanco
Narrator: Kyra Schlining
Motion Graphics: Madeline Go
Production team: Larissa Lemon, Raúl Nava, Marike Pinsonneault, Kyra Schlining, Nancy Jacobsen Stout, Susan von Thun, Lila Luthy, Kristine Walz
Music: “Veil of Maya” by Guiseppe Rizzo

References:

Hopcroft, R.R. and B.H. Robison. 1999. A new mesopelagic larvacean, Mesochordaeus erythrocephalus, sp. nov., from Monterey Bay, with a description of its filtering house. Journal of Plankton Research, 21: 1923–1937.