Fleshy worms with a thick reddish purple front region tapering to a narrow yellowish tail. They have thirteen pairs of red gills in the mid part of the body.
Found in soft sandy mud below mid tide, constructs U-shaped burrows. The burrow has three sections, A head shaft filled with subsided surface deposits, a horizontal section, occupied by the worm and a tail shaft through which the respiratory current enters. The head shaft has a depressions and the tail shaft is raised and has a typical worm "cast"
Feeds on organic detritus at the surface of the sediment.
http://www.annelida.net/nz/Polychaeta/Family/Arenicolidae/abarenicola-affinis.htm (accessed 08/02/13)