FARTHEST SOUTH.

New Zealand Herald, Volume XLI, Issue 12546, 13 April 1904, Page 6

FARTHEST SOUTH.

POLAR BIOLOGY.

AN INTERESTING REPORT.

[copyright.]

Referring -to the biological results of the Antarctic expedition, Dr. Wilson reports: —With regard to the zoological investigations of . the Discovery, nothing has been done in the deep sea. It is true that an attempt was made to dredge in 2030 fathoms when in the pack, and the first lesson in deep sea work, a somewhat expensive one, was learnt. A single haul with a trawl lias been taken in 500 and another in 300, but neithei of these can be regarded as completely successful. In the first case the trawl fouled, and in the second the cod end gave way at the last minute. All the other work lias been done in shallow water, at ox inside the 100-fathoiu line, and largely in the Laminarian zone. CORAL AND POLYZOA. '■ Ross, in his cruise in these regions, reported the existence of large quantities of coral in the sea which now bears his name, but we have every reason to believe that he referred to the polvzoa. Outside scientific circles few people distinguish between the two. A single haul of the dredge at 100 fathoms would bring up 10 to 20 species. Tangles let through sea holes are equally productive, though the area reached by them is but small, never exceeding a circle 2yds in diameter! This will indicate the enormous profusion of this form of life to be found in these southern seas. Polyzoa may be readily distinguished from corals by the fact that the individual animals are almost exclusively microscopic. They have a mouth surrounded by a fringe of tentacles, but their internal organisation is exactly comparable with that of animals much higher in the scale, whereas corals are nothing more than sea anemones having the power of secreting an external skeleton of carbonate of lime, which may be very massive. Their organisation is quite simple, the body, rarely as small as the largest polyzoa, consists of a cylindrical chamber only partially divided into a number of others. With few exceptions all waste food is discharged the same way it entered. Both live in colonies, which may include several thousand individuals, but the delicate lacelike cliaractei of the Polyzoa, whether limy, horny, or leathery, is, in itself,'quite sufficient to distinguish them. For all practical purposes it may be said that there is no tidal or littoral zone in the Antarctic.

Where it should exist the shore is precipi- j tons and inaccessible, or it is hidden under i a permanent ice-face. In winter quarters . most of the work had been done in the Laminarian zone. When the water was I open, dredge, and trawl were used; since j then small traps, nets, bags, and tangles | have been employed with a variable amount of success. . ~ FISHES. Fishes have not. been captured in large numbers or in great variety, though, from | the number of seals in the neighbourhood, and the contents of their stomachs, they are known to be numerous. Large numbers were taken bv hook during the summei months and used for food, others (100 or more) have been taken in box-traps; but for the moment their use has been discontinued. They seem to avoid the uet ; traps altogether. Notothenia, or Irema j tomis, are the genera to which the larger! Hill belong. These are genera of shallow i water iishes confined to Antarctic and 1 southern seas. Another and very much J «,mailer species, Harpagifer, is not infre- j quentiy taken in the trawl. Among the molluscs or so-called shellfish the captures have been unexpected. A lima is very common, end the broken shells of some species of Gaper are abundant, although the animal itself has not been seen yet. One whelk-like form lias been taken (Trophou), and four or live species of those scientifically known as udibrachs have been met with. These , are slug-like molluscs without any percept- j ible shell, but the back is more or less | thickly covered with long pap ill re, and are ( often beautifully covered. No cuttlefish have been taken, but their beaks have been found iu the stomachs of Emperor penguins and seals captured in winter quarters. CRUSTACEA. The group Crustacea is the best represented, and of this group the Amphipods demand the greatest attention on account of their numbers. Something like. 40 j species have been taken, and more than' | half of them belong to a single family. ] 01 one species some 60.000 have been taken in not more than half-a-dozen hauls of tho trap. From tho way in which the seals behaved as they come to the holes to breathe, the natural holes they make themselves as well as the artificial ones made for scientific purposes, there can be little doubt that there is an appreciable mortality among them ou account of their inability to get to a breathing-hole in time. That 60,000 Ampliipods at the very least should be taken in such a short time in an area of less than half a square mile indicates an enormous number in the neighbourhood, and that again an abundant food supply. The food consists of dead bodies of all sorts; seals, and possibly penguins, seem to form the most, important supply. No other animals would necessarily sufi'ei from an ice-covered sea, but it i.-: certain that this Aniphipod goes about in vast hordes iu search of such food. Isopods are numerous, but mostly of dijminutive size. A comparatively few members of this group are much more than an iuch in length, but in winter quarters some 20 species have been taken, aud our of them a giant of the group. Five Specimens, one a skeleton, of probably a new genus, three to lour inches in length, were taken by the tangles in 10 and 100 fathoms. Nebalia, iv curious little crustacean of rather doubtful relationship, was taken in some numbers during the summer. It very

closely resembles the species so abundant at Home. The highest group of Crustacea is only represented by two species of shrimp, both from 100, to 500 fathoms in the Rosa Sea, and two species taken from the stomach of a seal in winter quarters. Of one of these species two specimens have Vsen taken alive and two specimens of probably • a third. - SEA SPIDERS. Between the Crustacea and the spiders is a group of beasts which, by various naturalists, are placed first in one class, then in another, and finally in a class apart. These are commonly known as the sea spiders, mainly from their length of leg and the fact that they invariably have four pair. They are found all over the world in shallow and deep water, but the Southern Hemisphere claims the largest and the greatest number of species. Some 25 species have 'been taken, and among them one which, having five pair of legs, will probably for ever dispose of their relationship to the true spiders. WORMS. Worms are very numerous, more especially the family which possess a dozen or more kidney-shaped scales on their backs, and also those which live in tubes. A Nemertine is very abundant, and this is a thick, -brown, slimy-looking beast which has hitherto proved very difficult to preserve. Another slender species has been seen frequently from decpei water, where it- swims freely, or perhaps only floats, but never taken entire. It would probably bo from 30ft to 50ft in length. SPONGES. Three species of sea anemone have been captured, one of which seems to bo a rather peculiar form. The sea firs and their relations, which show a connection with the true corals, have been very abundant, but the most characteristic features of the winter quarters is the predominance of sponges. These are very numerous, both in individuals and in species, some of them so large that there are no vessels on board to accommodate them. WELL REPRESENTED CLASSES. One class of animals is particularly well represented in these southern seas, and that includes the starfishes, sea urchins, or sea-eggs, and sea-cucumbers. Of the firstnamed, one deep red species is extremely common in southern waters shallower than 100 fathoms or thereabouts. Two other very large species have been taken in winter quarters, and two smaller ones are common. The brittle stars are represented by four or five species, and those are generally broken when captured. A feather star or crinoid is not uncommon about the 100fathom line. Of the sea-urchins, one closely resembling a common English form is very abundant; another, which keeps

its young in little pouches for some time, is not uncommon; but some beautiful_ species were taken in the Rosa Sea, with a few spines, and these several inches in length. The sea-cucumbers are uncommon, and only a single white species is found in winter quarters. Others have been taken in the Ross Sea, among them one or two curious deep sea forms. As regards those forms of life included in the term Plankton, they are numerous, though perhaps not quite so numerous as elsewhere. The schizopods (chameleon shrimps) are abundant, and one species, Euphausia austral is, found first on entering the pack, and remaining with us until past Cape Ada.ro, constituted tue main food supply of the local seals and penguins. Among the jellyfish, the ctenophores or sea-lemons, are the most conspicuous. and the most difficult to preserve. They "derive their name from eight, rows of plates, by the vibration of which they move through the water. One large periphvlla. was captured by Lieutenant Shackleton in August, and other species have been taken more recently, but in disappointing numbers. ROSS SEA. Up to the present a fair amount has been done, but there is still a lot of gaps to fill up. One tiling can hardly receive adequate attention now, and that is the Ross Sea. Our knowledge of that sea zoologically remains pretty much where Ross left it. Referring to outside the 100-fathom line, what little the Discovery has done in that area shows that there is a wealth of life awaiting the explorer, but with short seasons and a multiplicity of interest all things are not possible.