NATURE NOTES

New Zealand Herald, Volume LXXII, Issue 22250, 26 October 1935, Page 1 (Supplement)

NATURE NOTES

TSY A. W. B. I'OWI'LL

THE QUAINT BARNACLE

What is a barnacle? Is it a shellfish? No, but one may be excused for considering it to be one. In fact, barnacles were regularly classed with true shellfish until Vaughan Thompson, in 1830, made the surprising discovery that barnacles belong to the same group as do shrimps and lobsters. He found that the young barnacle was a freeswimming, shrimp-like creature that soon tired of the orthodox behaviour of all good shrimps and lobsters and decided for the rest of his days to cast from his eyes the sight of the world by standing on his head, fastening it. to a solid foundation of either rock or wood, growing a shell around the body, and finding a new use for old legs by altering thein into feathery feelers, which he now uses with much bowing and scraping to comb food particles from the sea and convey them to the mouth.

The position was neatly expressed by the celebrated Huxlev, who described the barnacle as a "crustacean fixed by his head and kicking the food into its mouth with its legs." However strange this life history of the barnacle may seem, it is a most effective means of distributing an otherwise sedentary species. In the larval-shrimp stage these minute creatures are free to drift or swim from their birthplace and form new colonies elsewhere. Any hard, clean surface suffices. It may be a rocky foreshore, wharf piles, driftwood or the hull of a boat, as all yachtsmen know to their sorrow. Only by means of this free-swimming larva can overcrowding be avoided, but it entails a terrific infant mortality. It is doubtful if out of the sixty million larval barnacles produced by an adult barnacle in one breeding season that more than two or three survive to make forced landings, as it were, in favourable situations and grow into adults. The great bulk of the progeny are quickly snapped up by all manner of hungry creatures swimming in their midst. Even those which escape the mouths of their myriad enemies have further hazardous adventures before they are assured of survival. It is only the fortunate few that drift to rest on rock or woodwork at the correct tidal level and in water of suitable salinity that are enabled even to commence their post-larval life. As the barnacle grows it receives attention from further enemies, its worst foe being the small whelk-like shellfish (Lepsiclla scobina), known as the oysterborer, which divides its predatory attentions between barnacles and oysters.

The small white local barnacles, however, although found on the hulls of boats, are not the true ships' barnacles, these being of very different appearance. consisting of a flattened white shell on the end of a long flexible stalk. Masses of these ships' barnacles are frequently found attached to driftwood washed up on our west coast beaches, and others are actually found adhering to the fins and lower jaws of fishes. The ships' barnacle has an alternative and much older name in goose-barnacle, and thereby hangs an interesting story. In medieval times it was firmly believed that a common European species of goose, found mostly around the seashore, actually hatched from barnacles, and it was not until six or seven centuries had passed that the idea was finally shown to be fanciful. Meanwhile, however, it was said that certain of the clergy in France took advantage of the popular belief in this fantastic life-history and claimed the "barnaclegoose" as a hsh in its nature and origin rather thau a fowl, in order that it might be used as a food on the fast davs of tho Church.

Perhaps the strangest of all barnacles is Coronula. There is only one place to look for this species, and that is on the flippers and lower jaw of two species of whales, cue being the common humpback which is taken regularly at tho Tory Channel and Whangamumu Whaling Stations. The whale barnacle is not a stalked or ships' barnacle, but is nearer allied to the ordinary fixed base kinds. In order to afford a secure hold, the base of Coronula is adapted for the purpose in a most interesting way, being divided into numerous hollow triangular compartments, the sharp partitions of which are inserted into the yielding skin of the whale. Hump-back whales have been observed at Whangamumu swimming around certain rocks and actually brushing their bodies against the rock, obviously for the purpose of ridding themselves of these unwanted commensals. This barnacle is best described as commensal; that is, it merely lives in association with the whale* and apart from causing irritation does not exact any food toll from its host, as in the case of true parasites.

The barnacle in this case has everything to gain, free transport and a varying diet, as the whale progresses from one feeding ground to another. , Feeding, of course, is accomplished as in typical barnacles by the process of raking m minute organisms with those feathery appendages which are really modified legs. But even the Coronula has its troubles, for one frequently finds that its hard resistant shell affords an excellent anchorage for a stalked baruaclo allied to the ships' barnacle, and I have even seen stumpy little Pvcnogonids or "sea spiders" with their legs clasped firmly into the fleshy parts surrounding tlie lid-like upper valves of the Coronula. Both these creatures must tnke a considerable toll of the food that would otherwise go to the Coronula; they literally snatch food from the very mouth of their host. They form quite nn interesting little specialised animal community, which is entirely dependent on tne existence of two species of whales. Should these whales bo exterminated what would happen to the barnacles? Would they adapt themselves to new hosts or perish with their present ones?

Tho largest living barnacle in New Zealand waters sometimes grows up to 2] inches high by about H inches wide, and is shaped somewhat like a tulip bud. Formerly, however, there lived in local waters a veritable giant of a barnacle that must have been nine inches or more in height. This fossil barnacle belonged to tin; Upper Oligocene period, roughly, about thirty million years ago, yet its remains are still to be seen embedded in the sandstone cliffs at Islington Bay and at Motuihi Island.

No account of the barnacle would bo complete without reference to those amusing lines of Mr. A. P. Herbert, the first verse of which runs like this: — Old Bill Barnacle sticks to hia ship. He nsvei is ill on the stormiest trip. Ujnside down he crosses the ocean, If you do that you'll enjoy the motion,