[2] They exhibit diel vertical migration, moving closer to the surface at night.

[3][4] They can occur in very dense swarms, as solitary zooids or as colonies.

They are barrel-shaped and elongated, with a rounded front and a flat rear.

Aggregate zooids are 7 to 52 mm (0.28 to 2.05 in) in length individually (excluding projections).

[2] The incursion of a large number of Salpa fusiformis into the North Sea in 1920 led to a failure of the Scottish herring fishery.