Comments by Sars (1903): Occurrence.Of all the marine Calanoids of Norway, this form is by far the most common, occurring often in enormous shoals, and thus sometimes giving the sea a conspicuously reddish hue. It is found everywhere in the open sea, more frequently at the very surface, though at times it may also descend to greater depths, or be carried by the waves and currents towards the shores or into the bays and fjords. Off the Norwegian coast, I have met with it from Vadsoe to Jaederen (Tananger); but farther east it seems to be superseded by the succeeding species. It moves rather rapidly, with abrupt bounds caused by energetic strokes of the natatory legs. At times, however, it is seen quietly suspended in the water, with the anterior antennae spread out to each side at right angles to the body, or proceeding slowly by rapid vibrations of the posterior antennae and the mandibular palps. The male is still more agile than the female, and the motion effected by the posterior antennae and mandibular palps is more energetic, in accordance with the somewhat stronger development of these appendages and the pertaining muscles, being changed to a somewhat jerky leap through the water. At some seasons male specimens are by no means rare, though the female sex always preponderates considerably in number. This Calanoid is eagerly devoured by some of our common food-fishes, for instance the herring and the mackerel, and in some cases, as stated by Prof. Rob. Collett, forms almost the exclusive nourishment of one of our great whales, Balcenoptera torealis.