Many phyla of worms are found in the sea, this body structure seems to be very successful. However most of these phyla have few species and many of them are quite small. The segmented worms (annelida) are an exception as they are numerous and many large. If you find a worm in the ocean it is most likely an segmented worm.

Segmentented worms are split into 3 main groups, hirudinea which are rare in the ocean, oligochaeta (earthworms are in this class) which are common in the sea but are all small and inconspicuous, and polychaeta or bristleworms which are very common in the ocean and many large and conspicuous. Bristleworms are therefore THE marine worms.

All of them have appendages (called parapodia) and bristles on the appendages. The appendages and bristles vary enormously in size and shape.

Bristleworms have quite diverse looks and some species can get quite large.. Some are similar as the rather simple looking earthworms while others do not look like worms at all. The feeding habits are also diverse; they are filter feeders, detritus feeders, scavengers and carnivores.

Bristleworms are important food for many fish species, especially haddock and flatfishes. Bristleworms have not been harvested commercially in Iceland but have been collected for bait.

Many species of bristleworms are found all over the ocean bottom in Eyjafjörður, and a few species are even planktonic.

HV

Hreisturbakur. (Mynd: Erlendur Bogason) Hreisturbakur. (Mynd: Erlendur Bogason)

Trjónukrabbi og sandmaðkshraukar í baksýn. (Mynd: Erlendur Bogason) Trjónukrabbi og sandmaðkshraukar í baksýn. (Mynd: Erlendur Bogason)