Pacific Nature Notes

Written for "PIM" by Charles Barrett, FRZS

New Shark From Papua

FISHES new to science are collected often enough, but mostly, they are small or of moderate size. The taking of a new shark is an event de serving comment. Galeolamna tufensis, described by my friend Gilbert P. Whitley, of the Australian Museum, Sydney, in the Proceedings of the Royal Zoological Society of New South Wales, is a whaler shark, coloured pale grey above and white on the lower surface, and with a blunt snout. The type specimen was hooked off Tufi Harbour, in the north eastern Division of Papua. Whitley, who examined three males and two females at Tufi and Port Moresby, says that the species grows to a length of at least nine feet, and is viviparous.

The common whaler shark or black whaler, a man-eater, attains a length of more than 12 feet, and may weigh up to nearly 1,000 lb. One taken by Zane Grey off the coast of New South Wales, weighed close to 900 lb. The huge surface swimming whale shark (Rhinedon) first discovered in 1828, is inoffensive. The largest of all known sharks, it reaches a length of 50 feet, and a full grown specimen weighs several tons. This monster, which could overturn a small boat by bumping it, inhabits the warmer parts of three oceans—lndian, Pacific, and Atlantic. Specimens are rare in Museums.

The whale shark’s mouth opens for ward. Its teeth are very small, and, like the basking shark, almost its rival in size, it “sifts” its food—vast numbers of small fry taken at the surface. There are several thousand of the harmless teeth in each jaw. One admires the patience of the naturalist who counted them. The long gill-rakers, not the teeth, are used for straining small animals from the water. I have seen several basking sharks, but have not had the luck to sight a whale shark during my ocean voyages.

The Remoras

IAM more interested in the “shark sucker”, or Remora, than in sharks; because of its remarkable habits and association with sharks and other big oceanic 'fishes. There are at least ten kinds of Remoras, with a wide distri bution in warm seas. The last specimen to come my way was not attached to a host-fish but was caught with hook and line near Possession Island, in Torres Strait. My aboriginal companion declared it to be “good tucker;” but I had my doubts.

The adhesive disc on its head, the Remora’s famous structural peculiarity, intrigues the scientific zoologist, as a wonderful example of adaptation: he be lieves the sucking disc to be the greatly modified dorsal fin of the fish—the spines, in the long course of evolution having become divided and bent out wards in opposite directions, finally be coming transverse plates which create little vacuum chambers when thev are raised, which happens when the Remora attaches its head to the body of a shark or any other “host”.

Any flat surface will do to try out the sucking apparatus. My hooked Remora, given the chance, immediatelv brought its head disc into action: and adhered so firmlv to the deck of the lugger, that it was loosened onlv by a strong pull forwards: pulling the other way only

served to strengthen its attachment, by raising the plates of the disc.

Remoras seem to favour sharks more than any other large fishes, and it is nothing to find several of them attached to a shark that has been hooked. But they will not be taken with the monster; as it is being hauled out of the sea, they drop off in a hurry.

Shark-suckers often attach themselves to turtles: and in some waters they are used by the natives in capturing green turtles. Tethered to the fishing craft, the Remora is thrown overboard, and should it make fast to a basking turtle, there is a good chance of the latter being houled up to the boatside before the sucker loosens its hold —the headgrip by suction.

Remoras are not parasites. Their huge hosts provide them with transport, not food. The sucker preys upon smaller fishes, and after a raid returns to its shark for another restful little journey.

Land Shells

WRITING from New Britain, D.A.B. gives his candid opinion of the giant snails, introduced by the Japanese as a source of food for the troops. They have multiplied beyond measure and become a pest to planters.

Seedlings, however well guarded, have less than an even chance of growing up, where the snails abound, says my cor respondent, who is trying to form a garden round his house. They are a major pest on the plantation.

A few shells of the giant mollusc were acceptable for a naturalist’s cabinet; but far more desirable were native land shells. including delicately beautiful Papuinas—the former homes of tree dwelling snails. New Guinea and Papua are rich in land shells, remarkable for their elegant shapes or brilliant coloura tion. They are, in my experience, rather difficult to find in the jungle. I wasted a day snail hunting in a Fly River jungle.

Enchantment awaits the shell collector who visits the Hawaiian Islands, which are rich in the tree-dwelling snails known to science as Achatinellas. Their egg shaped shells, beautifully banded and coloured, with a porcelain like surface, display infinite variety. Being stay-at homes, the Achatinellas of Hawaii have developed a large number of races. Each valley is sain to have its own race of tree-snails. This may be an exaggeration; but certainly there are very many valley varieties. An Achatinella specialist, as Paul Bartsh declares (in “Fishes and Shells of the Pacific World”), dropping on to one of the Hawaiian Islands from a parachute, could name not only the island, but the valley in which he had landed: the tree-snails would give him his bearings.

An old collector, who sent me some of his gleanings in the Philippines, wrote almost with reverence of the land snails, some of which he said almost made his eyes pon nut of his head, the shells were so beautiful. And he came from Florida, where tree-snails of the everglades live in exouisitelv coloured shells. A series in my cabinet I owe to Charles Torry Simp son, author of “Out of Doors in Florida” (a delightful book), who formed a great collection of marine and land shells, and was a generous giver of specimens.

Snail shells may. to the uninitiated, seem to be queer things to collect. But in beauty and interest they rival cowries and cones and other favourite marine

shells. They have always fascinated me and I think gratefully of the missionary in Papua who first made me acquainted with Papuinas, by sending a few dozen specimens through the post. They were badly packed and some were broken in transit: but the “survivors” are still among the gems of my shell cabinet.

An English authority on the anatomy of land molluscs, wrote to his sister in Australia, asking her to send him a small lot of native snails, preserved in formalin.

The lady, as ignorant of conchology, as her brother was learned in science, went

Communications from Nature students in the Pacific Islands are welcomed by our contributor—Mr.

Charles Barrett, “Maralena,” Mays bury Avenue, Elsternwick S 4, Victoria.

°fl nt ° th , e garden and collected a score ol shellbacks among the violets. In due time the specialist received these com mon garden snails—the species introduced into Australia from Britain many years ago. Disgusted, the Doctor wrote to me, telling the story and appealing for speci mens of our remarkable land molluscs one of which—a tropical form—has a shell almost as large as that of the giant snail of Japan (and of New Guinea nowadays).

Tiger Beetles, And Others

INSECT “tigers” of the tropics are being studied by a coleopterist, who wonders why so few people in the Islands are interested in beetles, while butterflies have admirers everywhere. “Butterflies for boys. Beetles for men, sir ”

The island of New Guinea, of course, abounds in beetles, many of them being large and splendid insects, such as the jewel beetle (a Buprestid) to be found among other places, at Milne Bay’ more than one inch in length, it is brilliant golden green in colour, with coppery reflections. Other kinds are shining green. The cobalt blue weevils of Papua are the most beautiful of all the snout beetles; not excepting the famous “Botany Bay” diamond beetle of Australia which attracted the attention of the earliest settlers. One Papuan weevil is blue, ornamented with glossy black bands.

Tiger beetles are so numerous in some parts of Papua that a good series of specimens may be collected by an active entomologist, familiar with the ways of these swift-running insects, which are voracious both in the larval stage and as fully developed beetles. The most re markable of many species, in shape it resembles a large ant and is of a purplish blank hue: a fine example of mimicry in nature that has deceived even an ex perienced coleopterist.

Another Papuan tiger beetle, purplish black and about one inch long, emits a pleasant odour like attar of roses—a scent so pervading that the presence of the in sect may be detected before it is seen.

The theorv is that this scent attracts the small insects upon which the tiger beetle feeds. In any event, it seems to be ever on the watch for prey, as it lurks upon the broad leaves of iungle plants.

Alfred Russel Wallace, who made vast collections in the Malav Archipelago, was the first naturalist to observe this curious beetle: he also discovered the ant mimicking species; and dozens of other forms. Later, D’Albertis came across them; and he noted that the pleasant scent of the “attar of roses” beetle had its source in a blackish liauid exuded from the mouth.