SCHOOL IN THE OPEN.

Star (Christchurch), Issue 18015, 27 November 1926, Page 21

SCHOOL IN THE OPEN.

studies in the great out-of-doors.

pj (By ,T. J. S. Corner, 8.A., B.Sc.) Th® “Star" has arranged with Mr J, J, S. Comes, BA., B.Sc, to gjs write a series of Illustrated articles which will give teachers and others a fuller appreciation of the Great Out-of-doors. They will jyjjj deal with various aspects of plant and animal life, as well as with inanimate nature. Questions and material for identification will n 3 ba welcomed.

ANIMALS OF THE SEA. Tt seems highly probable that the seas were the first homes of life—the primeval seas that formed as the earth's crust cooled. Perhaps these simplest lifeTorms-could feed, as green plants do, by using the energy of sunlight to build up carbon-compounds from carbonic ' acid gas and water. They probably free-swimming units of living matter, somewhat like the simplest of the minute green Infusorians which, are found to-day in the open ocean. Probably they were at first very short-lived—perhaps creatures of a day, growing in the sunshine, multiplying in the evening, dying in the night. When buckling of the outer part of the earth’s crust led to the making of continents, the first great step on life’s ladder was taken. In the shallow, welllighted inshore waters some of the primeval forms of life began to anchor themselves on the rocks, growing- out into’ green threads and fronds, beginning the great race of fixed seaweeds or Algse. But from among these there probablvr emerged a new kind of life, minute, predatory creatures, feeding, nut on air * and water with the sun’s aid, but on. the seaweeds and their fragments,- and .by and by on one another also. '1 hey got the sun's energy secondhand; they stole the plant's munitions and exploded them. They were, then, the first animals and it is very unlikely that their appearance can have

been les? remote than five hundred millions of years ago. About these beginnings certainties are lew—but all naturalists are agreed that the animals of the sea began from very small and simple specks of life. Probably also there were millions of years of slow progress in the sea before the fresh waters began to be colonized. Thus, if y>c take the two lowest groups of many•celled animals, the sponges and the stinging animals, we find only one family of fresh water sponges, but scores in the sea, and perhaps a dozen kinds of freshwater polyps (e.g.. Hydra) and meduspids. but thousands of kinds in the sea. This practically proves that these two large groups had a marine origin—and the same conclusion holds in many other cases. The sea, then, is the great cradle of animal life, and also its great school. Let us say a little about the conditions of life in each of the three great haunts of the oceans. These are (1) the shore, (2) the open sea, (3) the ocean depths. More technically we speak of the littoral, the pelagic and the abyssal faunas. The shore or littoral area includes the comparatively shallow, well-lighted, sea-weed growing area around continent and island. It is peopled by a very large and representative fauna—indeed, it is the richest of all haunts of life. Its roll-call would take longer than that of tropical forest or temperate rain forest, such as our West Coast bush. Very briefly to run down the lists—Mammals, represented by seals, birds by gulls, reptiles by lizards and amphibians by frogs (on some foreign shores), fishes by “ gufties,” sea-squirts in large numbers, molluscs by octopus, cat’s-eye and mussel: crustaceans by crabs, worms almost innumerable. Echinoderms represented by starfish and sea-urchin, numerous stinging animals like sea-anemones and sea-feathers, numerous sponges, and then a host of almost or quite microscopic single--1 celled animals, the Protozoa. Yet the shore,.crowded as it is, is a j hard school of life. There are the tides to contend with, and storms and freshwater floods, and smothering wreckage and shifting sands and grinding stones. There is a struggle for food, which the tide sweeps from' the grasp, for standj ing room and for oxygen. There arc I risks of dislodgement and smothering when tide and seas are high, and of drought when the tide is out. There •is’the appetite of enemies all the time. The shore is an arena where we sec not only the struggle between fellows, but also the answers-back to the thrusts'* and arrows of an . outrageous physical environment. No wonder it abounds in “shifts for a living ” (such as blind pea-crabs liying in mussel shells) and life-saving devices like protective colouring. But it is rich, too, and beautiful in devices that are not self-regarding, but intended for the welfare of the offspring and of the race. It is the school where, after untold ages, good qualities have become ingrained—the quality of holding tight, which leads on to endurance; the qual-

itv-of biding their time until the tide, returns, which leads on to patience: the quality of push, which leads on to endeavour, and the quality of seizing a good opporutnitv, which leads on to alertness and initiative. The Open Sea. Very different from tlic shore is the open sea. the pelagic realm. Here on the surface there is almost limitless room, abundant floating food, and great uniformity of physical conditions. The pelagic animals live, as usual, to , some extent on one 'another, but depend fundamentally on the floating sea-meadows of simple green algae. Let lus call the roll from below upward— . Night-light infusorians (noctiluca) that J I with phosphorescent bacteria make summer seas luminous, chalk-forming globigerinids, jelly-fishes and Portu- ; gese men-of-war, virulently stinging, 1 worms, crustaceans, skimming insects, even, and such delicate molluscs as the Argonaut. Across the boundary line ! between liackboneless and backboned j come representatives of the sea-squirt ' class, -such as the salps, common in |

Dunedin Harbour, open sea .fishes like I the flying gurnard, retries like the loggerhead turtle, birds like the stormpetrel, even mammals such as the I whale. They can be divided into the { swimmers or nekton, and the easy-go-ing drifters, or plankton. For the drifters it is important to I be lightly built; there may be long , streamers to prevent sinking, or reservoirs of gas, or stores of oil. And often there are powers of sinking below the surface when “white horses” appear. The open sea is a safe - cradle for I young life, and it must-be remember- i ed that the young stages of many j shore animals, such as shore-crab and I sand-star, too delicate _for the rough-i and-tuirfble life among the rocks, are | found in the safe nursery of the open sea, far from their .birthplace and their future home.

. The Deep Sea. Hut in many ways the strangest of all haunts is the deep yea.-the floor of the great ocean abysses and its layers of dark water. The deep sea occupies more than half the surface’ of our globe and includes depths that would easily engulf Mr Everest. There is enormous pressure a pressure of. say. five miles of water above, as compared with that, equal to 32' feet of water, under which wo move—-that is a pressure of some 2* tons to the square inch as compared with out L| powmL. There is eternal winter, with a temperature at about freezing point of . water: there is eternal night for r-• i daylight far above ooes not reach such depths; there is eternal silence, and calm. There is no scenery, no vegeta- } lion, because of the darkness—but a dreary succession of undulations like * desert sand dunes Hut this eerie world is not -a blank, I for there is no depth limit to the distribution of animal life. There are 7 ! many microscopic creatures' —foramini- [ fers, sponges, sea-anemones and corals, :

worms in abundance, starfishes, seaurchins.'and stalked sea-lilies (crinoidff), numerous crustaceans. lamp-shells, mollusc?, degenerate - sea-squirts, and strange fishes, often luminous with a % phosphorescent light. Many deep-sea animals.-such as the sea-lilies, have long stalks raising them out of the soft, treacherous, smother- * ing ooze. There is exquisite sense of -r touch, for where sight is useless, tactility becomes the important sense. The bodies of these deep-eea creatures are ’ of rather watery composition, became the permeation with water .allows tne pressure within the body readily to r equal and neutralise the high pressure • outside. But whichever of- them you consider, it shows the same fitness to environment, and the same beauty of form, as the aminals - which are more - often seen -by us. (To be continued next-Saturday.) ,