Art. XXXVIII.—The Crab-eating Seal in New Zealand.
[Read before the Wellington Philosophical Society, 17th November, 1920; received by Editor, 31st December, 1920; issued separately, 8th August, 1921.]
So far as I am aware, the crab-eating seal (Lobodon carcinophaga)* has not hitherto been recorded in the New Zealand area, and I have therefore to note the two following instances. In both cases the specimen or a part of it has been preserved.
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In the Wanganui Museum there is a stuffed skin, with the skull included. It was stranded on the beach outside Wanganui Heads (S. lat. 39° 56') some time previous to 1892, and was referred to Leptonychotes weddelli by Sir J. Hector.† It is entirely white, with the dental formula C. ⅔, I. 1/1, M. 5/5 = 32.
The second specimen, an aged female, was observed in April, 1916, off Petone Beach (S. lat. 41° 14'), Wellington Harbour, where it remained a few days. It was then captured and taken to the Newtown Zoo, but died the following day. The skull is preserved in the Dominion Museum, Wellington (Plate LVI).
The record of this species in New Zealand is especially interesting on account of the great distance between the natural habitat of this seal, the Antarctic pack-ice, and the few northern localities where stragglers have been obtained. Besides the two specimens now recorded, stray examples have been taken at San Sidro (S. lat. 34° 28'), north of Buenos Ayres; at Melbourne (S. lat. 37° 45'); and at Portland (S. lat. 38° 20'), Victoria. The usual northern limit of the species is stated by Dr. Wilson to be between 58° and 60° S. lat. It is found chiefly in the pack-ice of the open sea, extending as far south as McMurdo Sound (S. lat. 77° 50'). It is the common seal of the pack-ice, and is found all round the Antarctic Circle. The occurrence of northern stragglers is, according to Dr. Wilson, explained by the fact that large masses of ice drift up into more northern waters from the south, no doubt very often with seals on them. But in this connection may be mentioned the following remark by Dr. Wilson‡: “Certain it is that Lobodon, notwithstanding its pelagic habit of life, tends to wander great distances at the approach of death, and to extraordinary heights up the glaciers of South Victoria Land.”
The crab-eating seal is easily recognized, notwithstanding the variation in its colour, by the nature of the teeth. The molars have each a large lobe with a small lobe in front and two or three behind, the lobes being slightly recurved and the spaces between them deep. Quoting from Dr. Wilson again,§ “The use of the extraordinary development of the lobes of the post-canine teeth in this seal was suggested by Captain Barret Hamilton in an article on the seals of the Southern Cross collection. These lobes, as he pointed out, form a sieve when the jaws are closed, through which the water can be ejected from the mouth, while the mud and crustaceans are retained and swallowed.”
[Footnote] * Hombron and Jacquinot, Phoca, Voy. Pole Sud, t. 10, 1842.
[Footnote] † Trans. N.Z. Inst., vol. 25, p. 258, 1893.
[Footnote] ‡ Appendix II to Scott's Voyage of the “Discovery,” p. 476, 1905.
[Footnote] § Nat. Ant. Exped., Zool., vol. 2, p. 34, 1907.