A larvacea caught in the Wadden Sea.

  • Taxonomy

    Kingdom: Animals

    Phylum: Chordata

    Subphylum: Tunicata

    Class: Larvacea (Appendicularia)

  • Locatie

    Marine waters, worldwide.

  • Size

    Usually smaller than 1 cm, sometimes much larger. 


Larvacea or Appendicularia are free-swimming tunicates, relatives of salps and sea squirts. They belong to the chordates, just like us! Larvacea look a bit like a tadpole with the tail planted at an angle. They look very similar to the larvae of sea squirts but the tail of Larvacea is implanted at a right angle, rather than straight behind the body as it is in sea squirt larvae.

Larvacea are filterers and make an ingenious slime filter to filter particles out of the water. Often they even make two filters; an outer filter to keep out too large particles and an inner filter to filter the desired particles out of the water. After a few hours, these filter housings become clogged, the larvacea swims out and makes a new filter. When caught, the filter instantly disintegrates, so photos like the one on top of this page do not show the true beauty of the animal in the water. For that, look at the research done by MBARI who scanned Larvacea in situ using lasers to study the mucous filters!

The empty filter housings of larvacea, full of detritus, sink to the bottom where they are an important source of food for bottom-dwelling animals, especially in the deep sea. In this way, larvacea also play an important role in the export of carbon to the bottom of the sea.