The pelagic tunicates known as salps (Thaliacea) float singly or in cylindrical or chainlike colonies that may reach several meters in length. The incurrent and excurrent siphons of salps are positioned at opposite ends, providing thrust for locomotion. Most salps are gelatinous and transparent. Salps are known from throughout the oceans, but are especially abundant in tropical and subtropical waters. They occur from the ocean surface down to around 1500 meters.
(Brusca and Brusca 2003)
