IN TOUCH WITH NATURE

Otago Daily Times, Issue 22256, 8 May 1934, Page 2

IN TOUCH WITH NATURE

OTHER MINDS BEHAVIOUR OF ANIMALS. By J. Dedmmond., F.L.S.. F.Z.S. Particularly ugly and fierce insects were found by Mr H. Hamilton at Rangatana, on the slopes of Mount Ruapehu. They lived in colonies and worked under cover of darkness, making pitfalls or traps, like inverted cones, two inches in diameter and one inch and ahalf deep in sandy soil on a sunny face. When each worker had completed its job satisfactorily it took up a position at the bottom, and there buried itself in the sand, but its head and its formidable jaws projected. In that attitude, constantly on guard, it lurked, waiting for a tly, a wood-louse, a spider, or any other little creature which, wandering on the sand, went over the edge and slipped to the bottom of the inverted cone. The jaws closed on it, it was killed, and it juices were sucked. •These diggers and sappers were ant-lions in the early stages of life. If Mr Hamilton had had time he would have seen each insect spin a cocoon in its trap, fall dreamily into inertia, become a chrysalis, and awake a lace-winged creature ot the air, like a dragonfly, and utterly unlike the ugly occupier of the trap in the sand.

Having greater opportunities, Dr E. S. Russell, lecturer at University College, London, studied ant-lions and their literature more extensively than anybody in New Zealand has studied them. He has shown how an*aut-lion began its work at Avignon, France. The first step was to trace a rough circle on the sand, lo do this it moved backwards, its body completely covered with sand, which it flicked out by rapid movements Of its head. To remove, pieces of sand much larger than its bo"3y it worked under them,' and pushed and carried them outside the circle. Returning to its task, it worked round the circle further in, resting occasionally. Little pieces of wood, tiny pebbles, or other small objects were balanced on the mandibles and were flicked out of the circle with a strong effort. When the trap was half made there was a mound in the centre at the bottom. The ant-lion worked around this in a furrow flicking sand all the time. The mound soon was reduced until the ant-lion, finding itself in a neat inverted cone the requisite depth, stopped work. The operation took about 15 minutes.

Dr Russell has .introduced the antlion into a fascinating book of 180 pages —“The Behaviour of Animals/ With all its skill and patience, the ant-lion is classed by him as a creature of routine. In one narrow and specialised line ot activity it is successful.. Confronted with unusual conditions, it is apt to become helpless. It will not eat unless it can pull its prey down beneath the. sand. It kept in a pillbox without food it declines food; it may ward off or attack insects it instinctively preys upon, but it will not eat them, even if it has had no food for two week. It knows and recognises food only in association with its traps. Unless it can go through the routine of pulling its prey beneath the sand it seems unable to act. According to another observer, so tar from being an ingenious and cunning trapper, as older observers believed, it is merely a highly specialised mechanism constrained by its structure to act in that particular way, and in no other way. From this point of view its life is a series of reflexes—a burying reflex when it covers itself with sand, a flicking reflex when it throws up articles, and a snapping reflex when it seizes its prey.

Professor W. M. Wheeler, of Boston, is convinced that an ant-lion’s effort to secure food, beginning with the construction of the trap and culminating in catching and killing prey, are directed by a desire to reach a goal. These are directed activities, not automatic activities. Details sometimes are adapted to special cii ustances. If an ant-lion, in making a uap, is up agaist an object too big to be moved* it abandons that site and makes its trap elsewhere. Professor Wheeler denies that the construction ot the trap is a reflex chaim of actions of an absolutely routine and invariable nature. Prey, generally, is not seized by a simple reflex snap. This is evidenced by the fact that if an ant-lion does not get a good grip at first it tosses the insect in the air or against the walla of the trap until it gets a better gnp. While this going on the insect may try to escape. In that case, the ant-lion, sends showers of sand after it to bring it down.

For these and other reasons Dr Russell discards the specialised automatic mechanism tehory in favour of the theory that an ant-lion’s behaviour is intended to satisfy the ant-lion’s needs. Instead ot being on rigid lines 'hat the ant-lion cannot control, it may be adapted to circumstances. At the same time, its instinctive behaviour is strangely stereotyped. In its narrow circle of normal activities it seems to be extraordinary clever. Confronted with something unexpected, it may act in an amazingly stupid way.

A delightful impressionist account of the methods of the trapdoor spiders is given by Dr Russell. It is taken frmn observations made by Professor W. E, Ritter of Californian trapdoor spiders. These artisans are interesting to New Zealanders, as they are plentiful in this Dominion. Scores of them may be found in their tubular dwellings in the ground if they are looked for in the places. A few weeks ago a trapdoor spider was seen lying in the sun near the WaitakiHydro electric works. On the approach of two strangers it ran into its home, pulling the trapdoor over the entrance. The trapdoor had been made of clay, the hinge of straw, and the home was cosy and beautiful. Californian < trapdoor spiders were taken from their nests as soon as they were hatched from eggs. They had no opportunity to learn, by imitation or in any other way,_ how to makes tubes or trapdoors leading into them. Placed in a pan of moist earth, they began at once to make tubes. _ iue young spiders were less than an eighth of an inch long, and their tubes _ were tiny, but they were copies in miniature of full-sized tubes, which, like_ New Zealand tubes, are about an inch in diameter and from four to seven inches deep.

A baby trapdoor spider begins by making a hole in the/ground, just large enough for it to get into. The mouth of the hole has a sharp edge, and is almost a perfect circle. To make the trapdoor a minute projection is formed on the edge of the hole. To this are added pellets of earth brought up from the bottom of the hole, which is deepened by this process. After each pellet is affixed the spider turns round and sweeps its spinneretes over the under-surface of the unfinished trapdoor, depositing there a silken cover. This is continued until the trapdoor is big enough to close the mouth of the tube. To Professor Ritter the most astonishing part of the operation is modelling raw materials into a nicely-fitting, freely-working trapdoor. Each deposit of clay brought from the bottom is shaped. This gives the trapdoor its circular outline and its right thickness. After the trapdoor has almost covered the opening it is pulled down from within several times with sufficient force to cause the bevelling that produces the nice fit, which is a conspicuous feature of the complete contraption. ,

It seems incredible that all this ingenuity, the building and the lining of the tube, the construction of the neatest trapdoor known, the bevelling of the edges to makes them fit to a nicety, and the fixing of a strong hinge is absolutely instinctive and unlearned, but the facts, as Dr Russell seee them, leave no room for doubt. In this excellent strain he discusses the behaviour of dogs, ants, birds, beetles, butterflies, fishes, crabs, earthworms, eels, molluscs, frogs, and other creatures. He places more value than is usually found in these books on knowledge possessed by shepherds, dogbreeders, fishermen, and sportsmen. His general conclusion is that animals are not mere bundles of mechanisms responding to stimuli. In spite of all the facts and of deductions, animals’ minds are almost as little known to human beings as human beings’ minds are known to most animals. This book is offered as an introduction to the study. A very useful one it is, and a good guide. A copy has been sent by the publishers, Messrs Edward Arnold and Co., London. Price, 10s 6d net.