The Paper -Nautilus'

New Zealand Herald, Volume LXXV, Issue 23009, 9 April 1938, Page 10 (Supplement)

The Paper -Nautilus'

Resemblance to an Octopus

Specially Written for the NEW ZEALAND HERALD, by R. A. FALLA, M.A.

WRITING from Okukari, Queen Charlotte Sound, a reader asks for a few notes on the Paper Nautilus, stating that at this time of the year a number are washed ashore at that part of the coast. Sometimes the shells contain the animal, sometimes not; while some have been found containing eggs. Several questions are raised: do they come ashore to shed their shells and grow new ones? Where do they come from, and why the migration at this time ol: year J Delicate Shell

rents. The animals thus found are all females, and they frequently have clusters of eggs within the frail _ detached shell. J'he only time the animal is herself in close attachment to the shell is when she is forming it, tor it appears to be but a temporary cradle o hold the season's eggs. The Swims and pushes the shell with her, but she is able to detach herself and Wave it. The puzzle concerning the whereabouts, or even the existence,. 0 males was not solved until it was discovered that they are comparatively tiny, sometimes as much as fifteen time, smaller than females, and have no external shell. End of a Family Empty shells stranded on a beach have probably been finished with, bu the stranding* of a shell containing animal and eggs means the end of that particular family. Thousands may complete the breeding cycle as the> swim and drift in a warm surface current far fro in land, but when such a current jinoinues on a coast a few are bound "come to grief. Their regular occurrence S cerSin localities in tfarch may mean that their breeding is seasonal in law. summer in the southern hemisphere, or ntav indicate that certain warm cur-

A partial answer to these questions may be attempted, for a certain amount is known about this nautilus and its habits. The delicate shell itself is well and widely known and admired for its pleasing shai>e and texture and its amazing lightness. It has.been recognised in paintings on vases of the Minoan period in Crete, showing that it had attracted attention as early as about 1200 "B.C. In the absence of exact information about its habits, however, ' "N

legends gathered round it and poetic licence pictured the shell as a boat in which the animal lay, raising its arms in the air: as sails, or alternatively dipping tlfem in the water as oars. Head and Mouth The starting point for k more strictly accurate account of, tjie Paper Nautilus must be to define its family relationships. From the fact of its having a shell It is fairly'obviously a mollusc and aiiy.oiie wlfo 'has seen the. animal will recognise 'its. rpsenjblance „,to an octopus.'Actually with the true, octopus it forms one spb-order (the eigbtarined group* of,the .class Cephalopoda, inolln'scs having their heads "and mouths situated in their'feet.-The related suborder includes the squids- and cuttlefish, and the remaining order takes'in the Pearlv Nautilus and .some extinct related* families.. It is" a.'curious assortment, no less interesfi.Ug-dfeiF-|tae. table and legend attaching Itp many of its members than for the array--ot zoological problems presented by their peculiarities of structure and habit. Nets Avoided The Cephalopoda are not only exclusively marine, but also for the most part they are pelagic. The open sea, from surface to depths of nearly 3000 fathoms, is their range and comparatively few species are confined to.shallower littoral waters. The specialist who attempts to study the group as a whole is dependent on chance to obtain much of his material, but has compensation in the fact that such chance may often present something new and strange. Up to the present time, mechanical devices for collecting at sea have not been successful in catching a representative assortnieut-of cephalopods, lor the creatures seem able to elude dredges, trawls, and tow-nets alike. The Paper Nautilus is an exception in that specimens do drift ashore complete, and at fairly frequent intervals 011 coasts washed by warm ocean cur-

On Great Barrier 1 am not aware of any exact information about, ocean currents in the New Zealand 'region that would answer • the question as to where the indivi- : duals entering Queen Charlotte Sound may have,come from, except that they are* currents borne from seas nearer the tropics; possibly via the Eastern Ausi trailian current across the southern Tasi man, up the West Coast, and through Cook. Strait. Specimens occur with some regularity at points along the whole of the West Coast and at the Chatham Islands. For the considerable number that.-strand on Great Barrier island and in the Bay of Plenty it wo|®|PW|!Ptti.ajble- .to assume passage by a south-flowing current. * •" Av 1 "' ' ' ' ' Not a Strong Swimmer When" encunibered with a shell the Papa/Nautilus does not to tie; a very strong swimmer, and its progress is probably more .in >the nature of a drift than an active migration. Some cephalopoda, however, are strong and rapid swimmers. The principal means of. propulsion is the accumulation of water within the cavity of the mantle -and its violeut expulsion bv means of a "funnel." -Those with elongated and streamlined bodies attain considerable speed in swimming. 1 once found one such stranded on the forecastle head of a vessel when only a moderate sea was running; it must have shot out of the crest of a wave passing level with the rolling deck. It is likely that many kinds occurring in New Zealand seas are yet unrecorded and specimens found that seem unusual should be sent to the nearest museum,% if possible to Auckland, where Mr. A. W. B. Powell has the necessary specialised knowledge to classify them.