WAYS OF THE WILD.

Auckland Star, Volume LIX, Issue 255, 27 October 1928, Page 1 (Supplement)

WAYS OF THE WILD.

A NATURALISTS NOTEBOOK.

THB XAUTII.ua.

(By A. T. FVCKOFT.)

The Argonaut, a skull found in New Zealand waters, commonly erroneously called the Paper Nautilus, was described last week. No doubt readers will now be interested to read about the Nautilus, which, like the Argonaut, is also a cephalopod, but differs in several respects. It has no ink sac, and is the only existing genus of Tetrabranchiate Cephalopods, that is a cephalopod having four gills. This mollusc, known as the "Pearly Nautilus," inhabits the Tn«lia.fi and Pacific Oceans. Numerous genera and species are found in the fossilised state, and a species of one fossilised genus of Ammonites is found in New Zealand.

D. F. Von Hochstetter tells us that lis had the pleasure of discovering a genus at Kawhia in 1859, and notwithstanding a long and tedious search, he had to be content with two specimens, both belonging to the same species. He called them Ammonites Novoscelandicus. There are many genera and species of ammonites and all are extinct, the typical form having existed only in the secondary, or reptilian age of the earth, when they were exceedingly numerous. The Nautilus from the Greek a ship, or sailor, is so called on account of the belief that it was furnished with a membrane which served as a saiL The shell is divided into chamber*, which are made or secreted by the tissues of the At first the creature lives in a single, nearly cylindrical chamber. As it grows, a new chamber is secreted, and a partition made between this and the old one. The animal slips forward into the new chamber, leaving behind it only a narrow cord, the "sipbuncle,™ formed from the tissues of the "mkntle of the Nautilus." A large number of chambers are formed in the same way, the animal moving forward each time, until a stage is reached when no more chambers form. All the chambers are air-tight cavities, filled .with a nitrogenous gas, and the sipbuncle extends through all the chambers into the one first formed. The chambers do not communicate with one another. The living animal cannot ordinarily rise to the surface of the water, but the shell is often to be found floating after its occupant has ceased to live.

The natural position of the Nautilus is with the head downward, tentacles spread out, and shell vertical. Nearly a hundred small tentacles, with which its food is caught, are placed on the area Hiirmmidifig the mouth. None of the tentacles has suckers, but each can be withdraw into a sheath.

The eyes are remarkable, for they are constructed on the principle of the "pin-hole camera." The eyes of no other animal are so constructed. They have been described as slightly projecting, hemispherical boxes, like kettledrums, a half-inch in diameter. The covering of the eye is not transparent, but like that of the head; in the middle of the structure Is a minute hole, which permits sea water to enter and fin the -eye. In general appearance and in structure the Nautilus resembles its relatives, the octopus, the squid, and the argonaut. In literature, and even in the accounts of naturalists, it is often confused with the argonaut. The Portuguese Man-of-War. I find among those who sometimes discover these queer floating creatures cast up on our ocean beaches and sometimes within our northern harbours uncertainty as to what they are, some writers refer to them as the nautilus, or Portuguese man-of-*ar, the latter is the correct popular name. They are jelly fish and to scientists are known as medusae, on account of their feelers, or tentacles, supposing to represent the hair of Medusa, who, in Greek mythology, wae one of the three Gorgon sisters, who, with snaky hair and of terrific aspect, turned those who gazed on them to atone. This jelly fish, with many others, belongs to the great group of rather simple animals known as coelemterata; the name implies that the stomach and body cavities are one. They are almost all jelly and not fish at aIL In some forms not much more than one per cent is really living matter. There are over a thousand species, varying in form, size and colour. A typical jelly fish is umbrella -shaped, with few or many feelers, or tentacles, and sometimes simple eyes around the edge of the umbrella, and with the mouth and stomach in the position of the handle of the umbrella. Simple muscles on the under side contract the body, much like the closing of an umbrella, and cause the swimming of the animal, and also enable it to swim into deeper water during rough seas. With certain explosive cells in the tentacles, small animals are paralysed and drawn into the mouth by means of the tentacles. Other organs one would not find—no brain, heart, blood vessels, skeleton or kidneys. Yet it is an animal in the fullest sense.

The strangest tiling about a jelly fish ie its life history. The egg hatches and swims about for a time as a very simple creature, wholly unlike the jelly fish. It thai settles down, becomes attached to some object and develops into a small polyp. There it grows and buds, much like a limb of a tree, and becomu a colony of polyps, looking much like a branched bit of sea weed. From polype there grow out finally tiny eggshaped buds, which open out, pulsate and swim away as little jelly fishes. These, in the course of weeks, or months, perhaps, in some cases years, grow to full size. Some jelly fish are just visible to the eye, some are two feet or more in diameter, some are so delicate as to melt in your hand, some are almost is firm as gristle, some are a* transparent as glass, others are brown, pmk, white or blue. They are manyshaped. Umbrella, egg or ribbon shaped or modified into queer floating creatures, as the Portuguese man-of-war. Most jelly fishes live at or near the surface of the sea. A Valvular Mollusc.

Mr. M. C. Walpole, Te Kopuru, sends a portion of a mollusc for identification. It was found at Whangaroa and resembles a butterfly in shape. It is one of the movable, dorsal plates of a mollusc, belonging to the family of chitons, or mail shells, so called on account of the mollusc being protected by eight movable dorsal ~plates or valves. This mollusc is' to be found adhering to rocks and under stones near low-water mark in sheltered situations, it creep* by means of a flat, muscular disc, or foot, on the ventral side of the body. Its scientific name is callochiton porosus. Molluscs of this Jtype are often erroneously called limpets; the liMtta, however, hfn non-eymmstri-spiral, «oofe«rfcf»| chap*