Annelids from the genus Nereis (Linnaeus, 1758)
Peter Wicht, an engaged and enthusiastic member of TaMOs who tragically died lately, provided us with plenty of pictures of his underwater observations. In his memory we would like to show according pictures. Peter photographed an impressive representative of the genus Nereis. We take this chance to elucidate some distinct characters of this genus.
Genus Nereis. Prostomium. (Picture: P. Wicht)
The anterior end of Annelids is frequently referred to as head - scientifically, it is called prostomium. The genus Nereis has a distinct triangular to pear-shaped prostomium. The prostomium is characterized by thread-like antennae and -visible at a closer look- four eyes on the dorsal side. Annelids of different genera also bear strong jaws that can be seen as dark structures in the beak (pharynx). When obtruded, their distinct dentition can be seen. On the picture Peter Wicht provided the antennae and the shape of the prostomium can be clearly seen. The two ventrally pointing prostomium appendices are the so called palpae. Jaws are not visible on this picture.
In the Baltic Sea different Nereis species can be found. All of them show a high similarity and are difficult to identify on species level. The genus has a circumglobal distribution, species numbers however are lower in tropical regions. The "prototype" showing all distinct characters of this genus is Nereis pelagica or sandworm (not to be confused with the lugworm though...). This species is frequent in the Baltic Sea.
Characteristics:
- Body length: 90-200mm
- Width: 5-8mm
- Coloration: Alive, this species often displays manifold coloration of often greenish, brownish, golden, reddish, violet etc. iridescence.
- Habitus: Body distinctly segmented with 100-150 segments. Lateral appendices. Parapodia clearly flattened, used for swimming and locomotion.
- Distribution: Nereis species are circumglobally distributed. Only few species in the Baltic Sea, e.g. Nereis pelagica, Nereis (Hediste) diversicolor.
- Taxonomy
Phylum: Annelida
Class: Polychaeta
Subclass: Ophistobranchia
Order: Phyllodocida
Suborder: Nereidiformia
Family: Nereididae
Subfamily: Nereinae
