Tomopteris (Neo-Latin from Greek meaning "a cut" + "wing" but taken to mean "fin") is a genus of marine planktonic polychaete. All described species are known to be holopelagic, meaning that they spend their entire life cycles in the water column. Generally they grow to only a few centimeters in overall length, or 20 millimetres (0.79 in) to 40 millimetres (1.6 in) in total length, though this is likely to reflect the size of those amenable to being caught in trawl nets.