Two non-colonial families: Salpida and Doliolida within the class Thaliacea
Salps are tunicates, animals that are invertebrate chordates, having all the chordate characteristics but lacking a backbone. They are thus more closely related to humans than are jellyfish or other invertebrates.
There are various subspecies.
From a few millimetres to several centimetres.
They are transparent, barrel-shaped organisms that may be solitary or in a chain. Muscle bands partially surround the body which opens at each end.
Many salps are luminescent.
They are found in warm seas. Salps are common in the southern hemisphere.
They inhabit mid-water.
Salps are filter feeders that have a mucus net in their hollow bodies through which they pump water. Microscopic phytoplankton and zooplankton become trapped in the net.
The life cycle of salps is complex, with alternating sexual and asexual phases. In the sexual phase, long chains of individuals are formed. Fertilisation is internal and the egg develops whilst attached to the cavity wall of the parent. It is eventually expelled from this cavity to form a solitary individual, which can reproduce asexually by budding.
They are not considered threatened.