IN TOUCH WITH NATURE.

Otago Daily Times, Issue 20800, 20 August 1929, Page 2

IN TOUCH WITH NATURE.

. CREATURES OF THE SEA.

By J. Drummond, F.L.S-, F.Z.S.

In the basin of Black Creek, a small stream- that enters the Awakino River, west of Mahoenui, Taranaki, there is a band of limestone 20 feet thick. It is composed almost exclusively of the remains of little creatures whose relatives have played a very important part in the world’s history. Placed in a row, about 25 of them would make an inch, jlreir bodies were as soft ns jelly. They lived when the waves, raged and swelled over that part of New Zealand. Their fascinating story would not be graven in the rocks if they had not learnt to secrete hard limy shells. These largely compose limestone in many parts, speaking of past ages, when continents, islands, and oceans occupied. different positions from those they occupy now. People who use limestone for structures probably do not realise that for the useful material placed so handy, and so admirably adapted for human needs, thanks are due to these strange creatures of the sea. In most cases, there are •opdnings in the shell, through which slender threads of the jelly-like substance are protruded. For this reason, these creatures are called the hole-bearers, Foraminifera. They arc so low in the social scale of the animal world that they have ho definite organs whatever, but zoologists have found in their methods some power that seems to be the power of selecting things that meet their humble needs. Material for the shells, for instance, often is taken from the bottom of the ocean in which the Toraininifcra live, and by them is cemented together. A definite selection is made from the mixed material. This is extraordinary, in view of the fact that the creatures have no organs or specially developed sense-cells. Some Foraminifera use a yellowish or reddish-brown cement to cement grains of sand in the shells. Others simply consolidate the material indiscriminately, using mud, grains of sand, other Foraminifera, and particles of sponges. There seems in these cases to bo no selection; the only purpose, apparently, is to form a hard protection for the soft body. t Against this some Foraminifera specialise exclusively on grains of sand, cemented firmly with material of a lighter colour. Only black grains are used. by some, although grains of other colours are available. Thu grains may be fairly even in size. There is a species that makes its shell almost exclusively out of other Foraminifera, seldom using grains of sand. The greatest ingenuity is shown by a Foraminifera that uses needle-shaped spines tqr the main jines of its many-angled shell, and fills in sides with broken spines. Another species malms its shell of the disintegrated plates of brittle-stars. Ihe number of these plates in any area is small, yet a Foraminifera of this group collects sufficient to make its shell of them on!y,_ probably using hundreds of plates. This is clear evidence of power of selection. If there had ffieeu no Foraminifera, there might be no pyramids in Egypt, to excite the curiosity and the wonder of modern civilisations, and there might be no Great Sphinx. The limestone used by the ancient builders of those days is* largely Foraminifera. Masses of it stretch across Africa, Europe, and Central America, in places 1000 feet thick. Without the Foraminifera, there would be no Oamaru stone. In the middle 6'{ the Cainozoic Era, Foraminifera, in countless numbers, established themselves on a submerged platform near Oamaru thrown up in one of the eruptions that occurred frequently there in Cainozoic days. The I‘orarainifera on the reef were destroyed by the volcanic activity. Their remains soon were buried beneath a eheet of ash and other material. When volcanic activity ceased, Foraminifera established themselves again, and built up the upper part of the Oamaru stone and the Kakanui limestone. A Foraminifera family that helped to make the Oamaru stone bears a title meaning ”to weave.” Its members are more primitive than members of most other Foraminifera families. Mostly, their shells are wholly or partly composed of sand, which is regarded as a primitive character. In early stages of development, these Foraminifera are coiled, and the coiled stage continues for a fairly long time. Foraminifera of this family are rich in ornamentation, in which knobs, bosses and spines take a part. There is‘ beauty in the curves of the shells and in their ornamentation, whose patterns often are intricate. There are species of Foraminifera with a world-wide distribution, ihe depths of their habitations jn the ocean range down to 3950 fathoms. The simplest form of covering in in a fresh water Foraminifera. Its shell is a kind of jelly, is flexible, and takes the changing form of its owner. A she]] may have a single chamber or many chambers, v a new chal ’ lber is needed, a part ot the creature is protruded from an aperture, and the new chamber is formed about it. A shell may have only one or , only a few, comparatively large holes. In another group, the walls of the shells are peq fora ted all over. Amongst the Foraminifera that are known best, on account of their extraordinary plentifulness and then- wide distribution, are some u llqse shells are only one-fortieth of an moh in dmmeter. Each of these shells usually Jigs seven round chambers, nrranged spirally in a way that all are V wbl ® f r om above, but only the Inst four uu i ?'!:■ Perfect specimens of these t-iells bristle with long, slender spines. The shell, when the Foraminifera is alive, is sunk in a bubbly mass of protoplasms, used ns a float in the water. Places, at depths between 500 and 2000 fathoms, over vast areas, the floor of the ocean is covered with pinkish-white mud, containing about 60 per cent, of 1 °f i‘ tllo ' luucl i s mainly , the shells of Foraminifera. The food of : 1 oramimfera is vegeable matter, diatoms and seaweeds providing the greater part, ■ , t ,n° mG F , O1 ‘ amln j fera cfl tch and eat other umnll creatures of the ocean. j I Foraminifera aVe still plentiful. Their * -hells still ram down from the surface of ntTn ™J; 0 i the bottom to > rm rock's WUud K fn 1 ? come m!l y crop up out of I lifn ii,J type ’ lk ® otl,er lo ' v] y forms ot life they are persistent. Thev have d f el °P. ad - advanced to a maikedl degree from the earliest geological traced tor n’ I,Ch history Ls been “i, ril iV P'eHtif.,l throughout the whole of the Cainozoic Era, estimated to have lasted for some 50,000,000 years, J hoy lived in amazing profusion in an ancient sea lethys, nAmed after the seagoddess, wife of Oceanus, ruler of the waves, ihe lethys Sea separated a great liuid mass, including Africa, Arabia, and V f V!- fi°m northern lands. Tlnf presence of Foraminifera m it is evidenced bv llieir remains in massive limestone beds (hat run from Western Europe to Further India, and to the Himalayas. The Foraminifera date back to the early, misty, mysterious Cambrian Period when there were neither birds nor mammals, neither , flowers nor Insects. On stones, on the piles of wharves and bridges, everything that is stationary for a long time in salt water, Foraminifera •no lonnd Aj;niy individuals, to tunny species, are found in the sand of line pools. Hardly longer than the grains "t sand amongst which thev live, their presence is disclosed by. a lens, and a microscopical examination -of a band of limestone like the limestone at Black (.‘reek, Mahocmii. may transport an observer from dry land to the bottom of the sea, from the present to the distance past when the Eoramiiiifern whose homes made I (be limestone lived and worked and filled their place in life, ;