There are many creatures suspended in the ocean that build elaborative feeding houses that have a special mission in carbon pump. One spectacular example are Appendicularians – pelagic tunicates known also as Larvaceans. As mucus net feeders, they build huge and really beautiful ‘houses’ around their bodies that comprise two layers of filters. By beating their tails, they drive a feeding current through those mucus houses, and in this way larvaceans are able to concentrate food particles and other suspended matter in the water column. Appendicularians discard their houses, when they get clogged and build the new filtration system. This process is very frequent, as may be repeated every few hours. Such abandoned houses in form of balloons of mucus filled with debris are the important source of large marine aggregates that contain massive amounts of small particles and which are sticky enough to collect also larger ones from the surrounding waters. This efficiency in production of filtration houses as well rapidly sinking fecal pellets play a massive role in an export of matter towards sea bottom. Consequently, they are thought to play an important role in influencing atmospheric carbon dioxide levels, and hence global climate.

Lurking within their snot palaces, they are tricky creatures to study, because only the homeless main body (“sea tadpole”) can be collected by plankton nets in undisturbed manner. Recently, owing to the underwater imaginary, the knowledge about their distribution and structures of their houses is improving as well as our ecological recognition of their great role in pelagic ecosystems.

Five species of larvaceans are known to exist in the Arctic, with several new deep-water species awaiting description. Recently new, previously unreported species were recognized in various Arctic waters. In our case, we spotted numerous well-known structures of houses of Oikopleura spp. in the upper water layers, but we also found suspicious, much less known and less recognized houses of absolutely different style in deep waters (below 400m).

Emilia