|Environment||Sandy and gravely substrate in shallow seas|
|Discoverer||Adolph Eduard Grube|
|Average Length||5.9 - 11.81" (15-30 cm)|
|Average Width||0.39" " (1 cm)|
|Prey||Barnacles, Clams, Mussels, farmed algae|
|Distinctive Features||Large, strap-like libules|
|Skin Color||Usually iridescent greenish-blue, but can be brownish or greyish|
|Phylum||Annelida (Segmented Worms)|
|Class||Polychaeta (Polychaete Worms)|
Nereis vexillosa is a species of ragworm indigenous to the shallow sea bed of the North Pacific Ocean.
N. vexillosa are a worm of varying color, from a brownish or greyish hue to even an iridescent greenish-blue. They are generally 15-30 cm long and are nearly 1 cm in width. They utilize large, paddle-like extensions from their body known as parapodia to move about. They also possess more prominent strap-like ligules at their posterior end, which can be used to distinguish them from other, similar-looking specimens. They have a pair of pincer-like jaws which it uses capture its prey but also to scrape algae that it has attached to its burrow entrance. It uses this algae to regulate temperature, moisture, and salinity during low tide, but also as a secondary food source.
The species inhabit intertidal and subtidal zones along the coasts for the Pacific Ocean from Alaska to the southern coasts of California on the eastern side and along the coast of Siberia to the west. There are rumors that they can also be found in South Africa. They prefer sandy or gravely sediment and can often be found around barnacle clusters or mussel beds.
Upon reaching sexual maturity, the species' body will change into either a heteronereid or an epitoke format. In this form they are full of gametes and their sole purpose is to breed. Those that become epitokous will leave their burrows and enter the water column to form spawning swarms. They will die shortly after mating is completed.
They can be difficult to distinguish from two closely related species, Nereis brandti and Nereis virens, though both are generally larger in size, growing to lengths of up to 1.5 meters. They can also be differentiated by having more rounded and leaf-shaped ligules (lobes).