Errantia polychaets are polychaets that are mobile, they do not build tubes or burrows into the sediment. They sometimes bury themselves into the sediment but do not make permanent burrows. They are often colourful with large appendages and bristles.

The most conspicuous of these are the ragworms (Nereididae). The common ragworm (Hediste diversicolor) can easily live in brackish waters close to the mouth of the rivers in Eyjafjörður. He is buried into the sediments when hiding but crawls around to look for food. His close nephew, the slender ragworm (Nereis pelagica) is common in the lower part of the seashore but is not as common as it does not tolerate brackish waters as well.

The largest of the ragworms is the sandworm (Neris virens). It can grow up to 90 cm long (36"), close to be classified as monster. It has recently been found in Eyjafjörður. On mud bottom, below the shoreline large individuals of the genus Nepthys are quite common.

Scale worms (polyonidae) do not bury into the sediment and are in fact most common on hard surfaces unlike other worms. Like their name implies theyr back is covered by scales along their entire back for protection.

Large worm of the genus Nephthys, about 10 cm (photo SHA) Large worm of the genus Nephthys, about 10 cm (photo SHA)

A small still unidentified polychaet (photo SHA) A small still unidentified polychaet (photo SHA)