THE MOSS-ANIMALS.

Hawke's Bay Tribune, Volume XVII, Issue 205, 13 August 1927, Page 4

THE MOSS-ANIMALS.

A specimen sent by Mr. H. Harrison, picked up by him near the Manne Parade, Napier, is a colony ol moss-annnals, creatures which do not come under public notice, and which are almost unknown except to those who study them, finding in their ways a very fascinating field of investigation. Only a few of them—-lace-corals and Neptune’s sleeves, for instance—have popular names, but to naturalists they are known, generally, in English, as moss-animals, and, in the official literature of natural history, as Bryozoa, two Greek words that have the sfime meaning as the English title. They have an official alias, Polyzoa—“polys” many, and ‘zoon’’ an animal —and some of them, in plain English again, are sea-mats. NOT A SEAWEED. Mr. Harrison describes his specimen as a seaweed. The moss-animals outward appearance led to their being classed as seaweeds until their real character as members of the animal kingdom was established years ago when the position of corals in that spacious realm was dis covered. The moss-animals were io; recognised until a struggle had taken place on their behalf. The great tinnaesus, compromising, classified them as partly animal and partly vegetable. He made a half-way house for them, and placed on it as a label the word “Zoophytes,” that is, animal-plants. Zoologists who strove to gain recognition for the mossanimals pointed out that there was no more reason for regarding them as relatives of the plants because they externally resemble a seaweed than there is for supposing that the bee-orchid is allied to the animal kingdom because of the peculiar form of its flowers. STILL UNDEFINED. Even when the controversy was set at rest, there was doubt as to the moss-animals’ position. For many years they were classed with the corals and the sponges, later with the wheel-animalcules, as hangers-on to the class of the earth-worms and the marine-words. They now are joined with the lamp-shells, the Bra-chiopoda—arm-feet—hut that is more a matter of convenience than anything else; there is no convincing evidence of the association of the two groups, and the moss-animals still hang nndefinedly on the tree of knowledge. W IN FOSSIL FORM. There are fresh-water moss-animals but most of them live in the sea; their range is from shallow water near the shore to the ocean’s abysmal depths. No fewer than 1700 living species are known throughout the world. Many species are represented as fossils found in rooks that date back to the era of Early Life. The number of’fossil forms is very great. Amongst living moss-animals, some favour places between tide marks, some prefer the mouths of estuaries, some are found on crusta-oeeans, some excavate tubular cavities in shells, some make their homes inside dead shells. Many marine forms have a surprisingly wide distribution. Several occur in places as far apart a 3 Norway and New Zealand. GROUP SPECIALISATION. One group is characterised by surprising specialisation .in the division of labour. In one colony in this group, there are fully developed individuals that discharge most of the functions of life, that is, respiration, taking in food, digestion and so on; the function of other individuals in the same colony is to anchor the colony to stones, shells or other objects. Other individuals, known as avicularia because of their resemblance to a bird’s head, are like pairs of forceps. Bv a complicated arrangement of muscles, the blades constantly open and shut, and these individuals turn from side to side, snapping in all directions, presumably to catch small marine worms, crabs and other creaitures. Long tnread-Hke structures, which work with a whip-like motion, it is believed. may help to drive minute prey into the reach of individuals that digest the food. DIRECTED MOVEMENT. There is more beauty in the marnie forms than in the fresh-water forms. The sea-mats rank high in this respect, but running them close in the beauty competition are Neptune’s sleeves. Between the open meshes of their delicate lace-work there are many minute apertures, the openings of chambers or cells that contain the bodies of the moss-animals. Most fresh-water moss-animals belong to an order characterised with a tongue, shaped lid to the mouth. Each has a crown of tentacles in horseshoe formation, surrounded nt its base by a kind of cup. Moving types of mossanimals form colonies that creep along, following the direcion of the light. Zoologists once were puzzled to explain how the large number of separate individuals in a colony all moved in the same direction. It was pointed out that even if light or other agency stimulated all the individuals in the same direction, it would not account for the movement of the colonv unless some nervous system coordinated the colony’s movements. A system of that nature has been discovered. Each individual is provided with a system of nerves for its own organisation, but the colony, ns a colony, has a special nervous system. This is connected with the individual systems, and it runs from one to

another by apertures by means of which body-fluids circulate through the colony. IN THE TE AUTE LIMESTONE. Some idea of the great numbers of fossil moss-animals is shown by the fact that a monograph on the mossanimal of France in the Cretaceous Period alone is a bulky octavo tome with more than a thousand pages and 200 plates. In some of the vast periods, moss-animals formed reels, which now are limestones. A fossil locality at Waipukurau, Hawkes Bay, is known mainly on account ot the many hundreds of specimens ol moss-animals collected there. Te Aute limestone, exposed along the Main South Road, passing Pukeora, is composed of massive beds about 200 feet thick. The limestone is rich in the remains of moss-animals. The largest and best preserved moss- > animals in that part are obtained from the highest points on the hills near Pukeora, especially from slopes near the hill-tops, and in grass below the outcrops. MORE ABOUT MUD FISH. An opnion is expressed by Mr R. Hastie Mangawai, that the mud fish is not as rare as is generally believed. He states that the first mud-fish he saw was in the jxaipara district, North Auckland, ft was about fifty years ago. He has seen it since in different parts of North Auckland. On his property at Mangawai there is a swampy flat with a clay sub-soil, in which he has found mud-fishes, usually in pairs. When making a dram on that flat three years ago, he found close to the surface, a mud-fish about five inches long. As the weather was wet, he thinks- that mud-fishes live near the surface in the rainy season. His theory is tint in the summer they seek a water hole at the bottom of which they form burrows, in blue plastic clay, where they seem to be able to live for a long time after the water has dried upST JOHN’S WORT

A spray of St. John’s wort, sent from a North Canterbury district, emphasises the fact that there is a menace in the starry yellow flowers of this pretty English herb. It occupies 150,000 acres in Victoria, is spreading in New Zealand Wales and South Australia, and has established itself in parts of New Zealand. An active principle it contains makes the skin of animals that eat it very sensitive to sunlight, resulting in fever and itching, and, finally in bleeding and swollen surfaces from rubbing and scratching. Dr. R. J. Tiilyard, states that sheep can eat the young shoots if with them there is a plentiful mixture of grass. He recommends aalt as the most effective means of eradicating small patches, but points out that the use of salt is much too costly where the plant is plentiful. Assuming that an effort may be safely made in New Zealand to control it bv its insect enemies, if the insects introduced will not feed on other plants, he suggests that the life-histories of several insects should be subjected t< starvation tests on plants of econoni. importance in New Zealand. PLANTS’ INSECT ENEMIES. The most important insect enema of St. John’s wort in Europe ale l"» beetles. These have been the subject of experiments by Miss Paterson a. Cambridge University. Other enema are the treble-bar moth, whose catei pillar feeds on the plant’s leaves am flowers; the caterpillars of othe. moths, which attack the leaves ano shoots; and insects that iorm galls and feed on seed-capsules. New Zealand has two natives allied to St. John’s wort. One of them rangethrough Australia and the Malay Archipelago to India, China, and Japan. Whatever character St. John’s Wort bears now, its old English names show that it formerly wain repute as protection from evil spirits. As “wort” is old English for “plant,” this sweetly pretty herb still stands in a matter-of-fact age, as St John’s plant.