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Page:Popular Science Monthly Volume 57.djvu/444

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434
POPULAR SCIENCE MONTHLY.

belong to the Crustacea, this memoir covers the greater part of the marine collection.

The Copepoda are predominant, especially those belonging to the Calanoid group, having been taken at nearly every haul along the whole route of the Fram. The zoölogical equipment of the Fram was based unfortunately on the supposition that the Siberian basin was shallow, so that the enormous oceanic depths which were found were only inadequately explored by an extemporized sounding apparatus.

While the results of the dredging operations indicate that there was very little animal life at the bottom of the ocean, on the other hand, it appears that the entire surface of the sea, which consisted usually of small temporary openings in the ice-pack, was covered with abundant life throughout the entire year even to the most northern latitudes.

Including surface and deep-sea specimens, there were taken on October 12, 1895, no less than eleven species in latitude 85° 13' N., longitude 79° E. On June 28, 1895, in 84° 32' N., 76° E., there were taken from the surface by tow net in a large water-channel fourteen species. This indicates abundant marine life in the sea immediately near the North Pole.

The pelagic animals, therefore, were not found at the sea surface alone, but were also drawn from considerable depths. Many specimens were obtained from strata at least 250 metres below the surface, and in a number of instances from depths ranging between 500 and 1,000 metres. It is to be added that the imperfect development of the visual organs of the peculiar amphipod, Cyclocaris Guilelmi, Chevreux, points to abyssal habits, as similar conditions do in the cases of other pelagic animals.

In general pelagic fauna in the Polar Sea resembles that of the northern Atlantic basin, the greater number of species being common to both. While several heretofore unknown forms collected by this expedition may be peculiar to the polar basin, yet it is not improbable that these forms also occur in the North Atlantic. This appears probable, since the western part of the Fram's route lies on the border of the two basins, where the fauna does not differ essentially from that in the eastern part.

While the pelagic fauna of the Polar Sea, even in the lowest depths, resembles that of the Atlantic basin, the great salinity of its water clearly indicates that it comes from the North Atlantic, and it is therefore more than probable that the migration of pelagic animals to the North Polar Sea is also from the west.

Indeed, Doctor Sars is of the opinion that the greater part of the pelagic life of the north-polar basin comes by the underlying easterly current from the North Atlantic. On the other hand, it is evident that the westerly-flowing surface current of the Siberian Sea is of vital im-