Invertebrates
Giant Larvacean
Bathochordaeus · also called giant larvaceans
Building a mucus filtering structure nearly a metre across around a body only a few centimetres long, a giant larvacean abandons and rebuilds this elaborate house several times a day, quietly shipping carbon to the deep seafloor with every discarded version.
Overview
The giant larvacean, genus Bathochordaeus, is a filter-feeding animal native to deep ocean habitat across temperate and tropical waters worldwide. Its remarkably oversized mucus “house,” rapid rebuilding cycle, and significant role in transporting carbon to the deep seafloor make it one of the more ecologically important, if physically modest, animals found anywhere in the ocean.
A tiny architect with an outsized impact
Despite its small size, the giant larvacean’s constant cycle of building and discarding elaborate mucus structures has real consequences for the wider ocean, quietly moving carbon from the surface into deep-sea sediment on a scale disproportionate to the animal’s own modest body.
Status
Least Concern, remaining widespread across suitable deep ocean habitat worldwide and not targeted by fisheries.
Giant Larvacean: common questions
What is the giant larvacean's mucus house for?
This species secretes and inflates a large, intricate mucus structure known as a house, used to filter tiny food particles from the surrounding seawater as the animal pumps water through it.
Why does the giant larvacean keep building new houses?
This species abandons its mucus house once its filters become clogged with debris, sometimes several times a day, quickly secreting a new one so it can continue feeding without interruption.
How does the giant larvacean help the deep-sea carbon cycle?
This species' abandoned mucus houses sink to the deep seafloor carrying trapped carbon and organic material, making it an important, if often overlooked, contributor to how carbon moves from the surface ocean into deep-sea sediment.
How big is the giant larvacean compared to its house?
This species has a tiny, tadpole-like body only a few centimetres long, yet its mucus house can grow to nearly a metre across, meaning the animal itself is a small fraction of the total structure it builds.