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Tiger brownlip
Tiger brownlip The rather rare allied cowry Pellasinia deflexa (Sowerby 1832), was first collected by Mr. Neville M. Jennings in North Queensland in December, 1967. Since then other specimens have been collected offering Neville the opportunity to study and photograph this interesting group. The shells range from about 15mm to nearly 25mm in length. There is considerable color variation with the shells ranging from white through shades of blue to an almost violet hue with some shades of rose and light brown - (See photo 1, 2 & 3... [right].) The mantle is nearly transparent with tinges of color along the fringes and in the tentacles. (see photo 1... [right].)
A more common Indo-Pacific allied cowry, Volva brevirostris, (Photo 4... [right]), is also collected in the North Queensland area with a near record size of 2-1/4" length being recorded. V. birostris is known from Japan and other areas. It is usually a dark brown color.
A sudden trip Down Under to Fiji, New Zealand and Australia came my lucky way recently. What a time I've had sight-seeing, making friends and especially shell collecting!
At the end of August seven of us left for Sydney to attend the 6th World Orchid Conference. Our first stop was at Nandi, Fiji, where we landed in the very cool A.M. – 4: 15 to be exact. We were met by an Indian driver who took us over a roller coaster washboard road to the small island of Yanuca.
Yanuca Island (pronounced Yanutha) has a horseshoe-shaped white sand beach of about six miles and the shelling seems unlimited. It's a favorite sport of the hotel guests and you can even rent shoes to shell in. A week before we arrived, one guest had found a live Golden Cowry [Cypraea aurantium] during a low tide and the hotel gave a real swinging party to celebrate.
As the sun came up I changed into beach clothes and went shelling. It was high tide but even so in fifteen minutes I picked up beach specimen of Cypraea moneta, C. cylindrica and C. carneola. Also Conus generalis, C. ebraeus, C. pulicarius, an unidentified Terebra, good Strombus maculatus, Oliva erythrostoma, black rose-mouthed Murex, countless bivalves including Cardium, also specimens of Natica and Turbo.
Tiger brownlip A gastropod, such as a littorine, after settlement on a preferred substrate, begins a rapid growth phase. As the mantle grows so does the shell which is formed by the mantle. The first portion of the shell deposited is the organic matrix (conchiolin). The pigment melanin is probably simultaneously bound to this protein matrix. Initially, the new shell is thin and lightly calcified although the pattern is fully developed. Additional deposition of calcium carbonate crystals occurs later. The pigmentation pattern of the shell depends on the localization of pigment-producing cells in the mantle edge and the temporal rhythm of transferral of this pigment to the shell matrix. The sculpture is dependent upon the areas of the mantle which fold, the size and extension of the folds, the resultant structure of the organic matrix and the temporal rhythm in the deposition of calcium carbonate, as well as in the production of the folds themselves. The basic temporal rhythm appears to be a 24-hr. interval. For example, in Philippine littorines, there is an endogenous 24-hr. rhythm in the formation of a new growth stria, in the production of pigment spots and the construction of sculpture nodes. During the maximmn growth phase prior to sexual maturity, L. pintado deposits a pigment spot in a spiral row every other 24-hr. period. Adjacent spiral rows are on an alternate rhythm so that the pattern resulting is a "checkerboard" (J). This species has no significant sculpture, but in a form of another, L. picta, each spiral row consists of a series of nodes, one node being produced per day during maximum growth.
Photos - uncredited
Strombus hawaiensis
Pilsbry, 1917
[ Images rotated to upright
for this display – B. Dayle ]
In many species, however, there are periodic elements in ornamentation that do not correspond to a 24-hr. rhythm. Some of these, for example the axial color in L. picta, the rhythm may be based on a lunar or semi-lunar period resulting from the interaction of diel and tidal components of rhythmic activity. In others, for example many Strombus species, the production of varices only at the shell lip may correspond to the cessation of growth at sexual maturity. In such animals as the Murex species, the regularity in the intermittent varices appears to be an inherent characteristic and relatively independent of environment, although in some cases it may be related to availability of food or seasonal change.
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