body uniformly reddish-orange or yellow-orange gradually getting pale toward the posterior, without a conspicuous color pattern, rounded head, lateral sensory organs are present

Biology/Natural History: Females have many eggs during the summer. Development is rapid and direct.

This nemertean worm, which can be up to 3m long, has a proboscis pore separate from the mouth, both of which are on the ventral side of the head. The head, which has a broadly rounded cephalic lobe, has no cephalic slits, no eyespots, and no anteroventral grooves. The body is a uniform bright orange, with no white stripes or lines. When contracted (see picture) it may be nearly as thick as a pencil.

Widespread from Pacific coast of North America to North Europe and the Mediterranean.

Belgian Exclusive Economic Zone, British Isles, Calais, Dunkerque, European waters (ERMS scope), Mediterranean Sea, Plymouth, Roscoff, United Kingdom Exclusive Economic Zone, Wimereux

cosmopolitan: Pacific coast of North America (Alaska to Puget Sound, Washington), Mediterranean Sea, Atlantic coast, North Sea, Channel and Irish Sea coasts of Europe, East Africa

Geographical Range: Aleutian Island, Alaska to Piedras Blancas Point, central CA

How to Distinguish from Similar Species: Most similar species have white stripes or lines, and may have some white on the head, and are ochre or brownish rather than bright orange.

Depth range based on 234 specimens in 1 taxon.
Water temperature and chemistry ranges based on 32 samples.

Environmental ranges
  Depth range (m): -0.5 - 610
  Temperature range (°C): 8.028 - 12.473
  Nitrate (umol/L): 3.089 - 30.530
  Salinity (PPS): 31.538 - 34.104
  Oxygen (ml/l): 2.000 - 6.561
  Phosphate (umol/l): 0.565 - 2.333
  Silicate (umol/l): 7.986 - 41.655

Graphical representation

Depth range (m): -0.5 - 610

Temperature range (°C): 8.028 - 12.473

Nitrate (umol/L): 3.089 - 30.530

Salinity (PPS): 31.538 - 34.104

Oxygen (ml/l): 2.000 - 6.561

Phosphate (umol/l): 0.565 - 2.333

Silicate (umol/l): 7.986 - 41.655
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

intertidal in sand and silt, lower shore intertidal under stones to shallow sublittoral depths of 45-50m or more, on mud, sandy mud, sand, or gravel bottoms, beneath stones, in laminarian holdfasts or among mussels and other growths

Depth Range: Low intertidal and subtidal

Habitat: Under stones embedded in gravel, in mud, or among mussels or seaweed.