A salp (plural salps) or salpa (plural salpae or salpas) is a barrel-shaped, planktonic tunicate. It moves by contracting, thus pumping water through its gelatinous body. This is also used for locomotion, and salp jet propulsion is one of the most efficient in the animal kingdom. The salp strains the pumped water through its internal feeding filters, feeding on phytoplankton.