Description:
Nereis vexillosa is one of sixteen species of polychaete worm (Phylum Annelida) that inhabit the B.C. coastline. It is the most abundant marine annelid in the Pacific Northwest. Their long grey-green body grows to a maximum body length of approximately 30 cm and consists of over 100 body segments! Each segment bears a pair of fleshy, paddle-like appendages called parapodia, which the worm uses for crawling and swimming.
The anterior end of the worm has a well-developed prostomium (or "snout"), which bears sensory organs, including four small eyes (ocelli) and two antennae. The prostomium projects, like a shelf, over the mouth. The mouth houses an reversible pharynx with pincer-like jaws that the worm primarily uses for territorial defense. So, they can bite!!!
The anterior end of the worm has a well-developed prostomium (or "snout"), which bears sensory organs, including four small eyes (ocelli) and two antennae. The prostomium projects, like a shelf, over the mouth. The mouth houses an reversible pharynx with pincer-like jaws that the worm primarily uses for territorial defense. So, they can bite!!!
Ecology:
Nereis vexillosa is found in the mid and low intertidal zones from Alaska to California, and coastal Siberia. Their preferred habitat is sand or mud that is mixed with sand, but they are also found amongst algae and eel grass, mussel and barnacle beds, and beneath rocks and woody debris in protected areas. During the larval stage, they build and live in flexible tubes constructed of mucus and debris (e.g. sand and stone). Sometimes they attach small bits of green algae (e.g. Ulva spp.) to the entrance of their tube which helps to keep the tube moist during low tides. Periodically, the worms use their jaws to snack on a piece of the alga. So, these worms grow their own food just like gardeners!
Although N. vexillosa is primarily an herbivore that feeds on algae, they will also eat small invertebrates. In turn, N. vexillosa are a very important prey species of shore birds and are also eaten by other worms.
Although N. vexillosa is primarily an herbivore that feeds on algae, they will also eat small invertebrates. In turn, N. vexillosa are a very important prey species of shore birds and are also eaten by other worms.
Life History:
Nereis vexillosa live for approximately two years. The sexes are separate in N. vexillosa. Breeding occurs in the summer and has been linked to the full moon. At this time, males and females swim to the surface where they form large congregations, presumably to maximize the chance that eggs will be fertilized. Males release sperm and females release eggs by rupturing their body wall. The adults usually die shortly thereafter. The fertilized eggs sink to the ocean floor, where they develop in gelatinous masses which hatch into larvae. Within 2 weeks of hatching they build mucus tubes and begin to feed and become territorial.
To learn more:
Woodin, S.A. 1977. Algal "gardening" behavior by nereid polychaetes: Effects on soft-bottom community structure. Marine Biology, 44: 39-42.