My last post introduced a giraffe who took a long walk. Since giraffes typically walk as part of their locomotion, the surprise of that story cannot be as great as the fact of the shrimp (prawn if you like) which walks around the high creeks and streams which flow down into the Derwent River in Tasmania.
(Photo courtesy of Parks & Wildlife Service Tasmania – http://www.parks.tas.gov.au/indeX.aspX?base=11244)
Geoffrey Smith, in his book A Naturalist in Tasmania (Oxford, 1909), describes the Anaspides tasmaniae. “A number of streams rise in the plateau of Mount Wellington, some of them attaining a considerable size before joining the estuary of the Derwent, and all of them characterised by the beautiful clearness of their water, owing to their beds being formed entirely of hard greenstone boulders.
In the pools of the upper reaches of these streams near the top of the mountain, a very peculiar shrimp-like animal is found. It is now recognised as one of those survivals of a bygone age of which the Australian continent has furnished so many and such interesting examples. The nearest allies of this animal appear to be some marine shrimps which come down to us as fairly common fossils in the sand deposited round the Permian and Carboniferous seas of Europe and North America: subsequent to this very remote period they do not seem to have existed in the seas, at any rate in the northern hemisphere, so that an enormous passage of the earth’s history has occurred between their peopling the northern seas and their survival on the mountain tops of Tasmania.
The Tasmanian Mountain Shrimp (Anaspides tasmaniae) is sometimes as much as two inches in length, of a brown colour, and walks about on the stones and among the weeds at the bottom of the pools, browsing on the mosses and liver-worts and any small creatures it can catch; it very rarely swims, but when frightened it darts forward by flicking its tail and takes cover under a stone.
In other parts of the world no trace of the animal’s survival has been discovered.
Goethe somewhere remarks that the most insignificant natural object is, as it were, a window through which we can look into infinity. And certainly when I first saw the Mountain Shrimp walking quietly about its crystal-clear habitation, as if nothing of any great consequence had happened since its ancestors walked in a sea peopled with great reptiles … time for me was annihilated and the imposing kingdom of man shrunk indeed to a little measure.”
The website http://www.anaspides.net/other/website_name_why.html believes “Anaspides tasmaniae has remained unchanged for 250 million years (Triassic Period): it is a living fossil. The first published record of Anaspides tasmaniae was made in 1893 from alpine pools on Mt. Wellington behind Hobart.” More details about this discovery, and about the later involvement of the author of the book excerpt above, Geoffrey Smith, can be read at http://www.tasfieldnats.org.au/TasNaturalist/Articles/1967/TasNat_1967_No8_Feb_pp1-2_Hewer_AnaspidesTasmaniae.pdf