Maurice Gray, of Oamaru, asks :-
On a recent climbing trip to Mt McKenzie on the main divide, my companions and I came across some amazing patterns created in the snow by an unknown creature. A circle was being formed the rebate was approximately 4mm wide and 2-3mm deep. On our return journey passing the same position, the circle was nearer to being completed by about 10mm in 1hr. A closer examination of the creature revealed it was about 4-5mm long, 3mm wide, and looked like a small chip of rock. On the underside showed some sucker like feet . The position of it in the groove indicated that it was moving sideways.
What was this creature and what was the purpose of the circle. ( Other shapes were being formed nearby.)
David Wharton, a zoologist at University of Otago, with the assistance of Brent Sinclair (Canada) and Hans Ramløv (Denmark), responded.
Sorry we can’t identify the creature from your description but some of the insects found in the alpine zone are accidental arrivals, having been blown there from lower altitudes (a process known as aeolian transport) and this may well be the case for the animal you found. After being deposited on the surface of the snow perhaps not surprisingly the animal is likely to be somewhat disorientated, as suggested by its behaviour where it is literally going round in circles. I can’t tell you what sort of animal your creature is but aphids, ants, flies, beetles and many other groups of insects; as well as spiders and other small invertebrates; are known to be carried up into the alpine zone by the wind.
There are, of course, a number of insects that are true alpine inhabitants but they tend to be found under the snow or under rocks, where they can get some protection from predators and the weather. Perhaps the rock-like appearance of your creature would help as camouflage but the effect would be spoiled by sitting on top of the snow. Some alpine insects are small and dark. Their dark colouration may help the insect to absorb heat in a cold environment and protect it against ultraviolet radiation, which can be intense in mountain regions. Alpine insects also tend to be wingless, to prevent them being blown away and deposited in an unsuitable habitat.
Perhaps the best known New Zealand alpine insects are alpine weta (Hemideina maori) and cockroaches (e.g. Celatoblatta quinquemaculata). These are both moderately freezing tolerant, surviving 74-82 per cent of the water in their bodies turning to ice and temperatures down to about -11°C. We don’t quite understand how they are able to do this but they produce cryoprotectants, such as trehalose, and ice active proteins that control the formation of ice in their bodies. Our alpine weta is famous for being the largest freezing tolerant insect in the world (weighing about 7 grams).