NATURE NOTES.

New Zealand Herald, Volume LXVIII, Issue 20988, 26 September 1931, Page 1 (Supplement)

NATURE NOTES.

BT .T. DEOtMOND, F.L.S.. F.Z.S.

GAY COLOURS.

Under a furrow in a ploughed paddock Mr. A. D. Shaw, Awanui, North Auckland, found a brilliant worm, yellowishgreen on top, grey below. In spirits its glorious colours vanished, leaving it a uniform pale grey. It is one of the flatworms, or land planarians, belonging to the Geoplana, a group of interesting creatures well known to naturalists all -the world over, differing widely in appearance. habits and life histories, but all having the same sort ot organisation.

These worms usually are brightly coloured, brilliant bands or stripes being the fashion. The significance of the colours is not understood. A few students believe that they are warning'signals to possible enemies, as at least some land planarians have a disagreeable taste. The principle behind this theory is that birds and others creatures, seeing the colours will know that their wearers are not fit for food, and are not worth wasting time on. Against this is the fact that land planarians mostly are nocturnal, living by "day under logs, leaves and stones, and in other dark, damp places. In other cases, the colours seem to be protective. That is, they so closely resemble the surroundings that they make it difficult to see the land planarians. Two New Zealand species that favour the beech forests in the South Island are brown on top and yellow below, these colours matching leaves in their haunts. Another New Zealand species looks like merely a slimy patch on the rotten bark on which it is found.

Nothing has been done with New Zealand's land planarians since Professor A. Dendy's time, more than thirty years ago. There are many new species to be discovered, and there is much to be written about their habits. Until about thirty-seven years ago the number of species ot land planarians recorded from New Zealand was very small. With the help of friends. Professor Dendv increased the number to about fifty. He found large individuals of a species, Geoplana graffi, under logs on the Teramakau Flat, near Jackson's, Westland. Thev had dark brown backs speckled with iridescent green, and with dashes ot opaque white. Beneath, they were very pale brown, moJtled abundantly with dark, purplishbrown. They were about three inches Ion?. They crawled rapidly, the lower surface being flat and the back concave. A variety that lives in the same place is shiny black on top. In rotten trees in the Clinton Valley, at the head of Lake Te Anau, there is a planarian that wears uniform bluish grey, and has many eyes; and in the same place and habitat there is a sluggish species whose back is almost uniform gamboge-yellow, and under surface yellowish-brown.

Geoplana splendens is splendid in its cloak, ornamented with emerald-green stripes alternating with warm, dark-brown stripes, all narrowly margined with pale grey. Each stripe is made of innumerable minute, brilliant metallic-green specks set- in a dark-brown background. This brilliant creature has been reported from only one place. Jackson's, west oi" Otira. Vie in 2 with it is Geoplana spectabilis, found under a stone in the bush at Wadestown, Wellington. On top it is a warm reddish-brown, almost chestnut, thickly with small irregular specks of bluish-white. Below, it is white speckled with reddish-brown. The thick scrubby bush at Alfnrd Forest, Canterbury, is a good hunting-ground for land planarians. Among those that dwell there is Geoplana latissiroa. On top it is orange, which shades into pinkish toward the head; below it is very pale yellow.

A skin of a land planarian is full of minute rods, shaped like needles or bent into a \ -rortn and bearing a slender thread at one end. \\ ben the creature is irritated, the rods are shot out in great numbers, probably for an offensive purpose. Largely or completely carnivorous, land planarians feed on earthworms, insects, grubs, small crustaceans and molluscs. A land planarian was seen to pursue and catch an earthworm, and take the earthworm into its pharynx, stretched as a thin skm over the struggling worm's body. A:ter one of these meals, which last from one hour to five hours, the land pianarian remains without food for a long time. An eyeless land planarian in Brazil pursues earthworms into their burrows. Sir J. A. Thomson, of Aberdeen, notes that planarians probably were the first many-celled creatures to have right and left sides, and to move consistently head foremost. He describes them as the simplest creatures with head-brains, and he looks back to them as the beginners of the line of progress that led toyman's knowing his right hand from bjs left. Land planarians have almost achieved immortality. They survive the ordeal of being cut into several pieces. If a whole is cut into four pieces the result, in time, is the formation of four whole" planarians. One New Zealand species, Geoplana sanguine.i, is identical with a verv plentiful Australian species. There is no reason to believe that it was introduced into New Zealand, as it has been found tar inland. Is seems to be indigenous to both countries. It might be expected that the land planarians of the Chatham Islands would be different from those on the mainland. This is not so. Of four species found on the Ohathams, only one has not been reported from the mainland. At least one species may have been carried to the Chathams on logs and other debris by a south-west current that sweeps to the Chathams from the coast of the North Island. Interesting visitors came uninvitingly into Mr. J. M. Jefferson's house at One Tree Hill and soon made their preseuce felt. Tliey appeared first after a supply of tea-tree blocks had been stored in a cellar under the house in the autumn of last year. From there they went all over the house, pushing their way into every room, even into the wardrobes and into the bedclothes and never neglecting a single room. Mr. Jefferson recognised them as cockroaches, although not the same species, Blatta orientalis. he knew in old houses in England. He carefully examined the tea-tree blocks. There were no live injects there, but most of the blocks had long holes bored in them by other insects. With the cold weather the invaders' numbers seemed to decrease. Mr. E. S- Gouriay, entomologist at the C'awthron Institute, has identified the insects as members of the common native cockroach, Cutlia brunni. He states that they infest houses occasionally, but seldom become a pest, as, unlike introduced cockroaches, they do not eat foodstuffs and other things they should not eat. If their hiding places in the vicinity of a house are removed, they may be prevented from remaining in the immediate area and soon will disappear. Mr. Gouriay add 3 that they like to hide under old timber, among log 3 stored for firewood, under sacks, and in many other places they consider suitable.