Some of them are produced by gelatinous animals called salps.
它们中的有些是由一种 叫做樽海鞘的胶装动物产生的。
英语百科
Salp
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. 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.