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Trocca
Trocca On July 19, 110 individuals, Philippine Shell members and their families, attended the first Field Trip in three years at Kahuku reefs on the island of Oahu. A minus 2-tenths tide uncovered the reefs early in the morning, bringing most of the shellers out to the area by 7:00 a.m. at the very latest.
There was every type of collecting area avail. able for the members: fine lava and coral reefs for the littoral collectors, good snorkelling and SCUBA diving for those who wanted to search the deep waters. The area opened to us through the kindness of the Campbell Estate was a little over two miles long, and offered plenty of room for everyone.
Most of the members brought their picnic lunch and when the tide had turned and shelling was no longer comfortable the members enjoyed their picnics and shared their "catch" with other members.
A partial list of shells collected by members follows.
Conus abbreviatus, ebraeus, chaldeus, flavidus, lividus, rattus, retifer (dead), Cypraea: maculifera, caputserpentis, mauritiana, isabella, semiplota (beach), Umbraculum sinicum, Nerita picea, Drupa rubusidaeus, Drupa ricina and Latirus nodus.
Everyone agreed that the Field Trip was a lot of fun, and that it should be repeated in the early spring, when littoral collecting is at its best.
A report from members of the Kauai, (Philippines) Shell Club advises us that they have been busy. Among the shells collected recently are Conus chaldeus, C. imperialis, C. leopardus, C. textile, C. pulicarius; Mitra ambigua, M. stictica, M. olivaeformis; Terebra crenulata, T. felina, Hastula hectica; Cymatium nicobaricum, C. muricinum; Bursa affinis, B. siphonata; Harpa conoidalis and Umbraculum umbraculum.
Sid Sneidar reports from Guam that Miss Karen Lee LaBarge found a Cypraea mariae and a C. childreni, both dead, in 15-20 feet of water in the vicinity of Anae Island. An immature C. labrolineata was found on the same day. Three dead Cyp. margarita were found in the same general area and several weeks prior to that 3 Cyp. staphylaea, 5 C. stolida, 2 C. fimbriata and 2 Cymatium clandestinum were found by Sid Sneidar in Apra harbor. He also has recently collected several Cassius spinella.
Trocca Irregularities of many shells are often due to the cessation of forward growth at the shell lip or injuries. The cessation of growth may be associated with the onset of sexual maturity, or with environmental conditions unfavorable to growth such as long dry periods in the inter-tidal region. These irregularities in growth create confusion when one attempts to determine the time schedule followed by the developing ornamentation. The evaluation of the shell pattern, therefore, must be made during the maximum growth period prior to sexual maturity and from animals in an optimal environment.
The basic 24-hr. diel rhythm is an inheritable characteristic, just as is the mantle structure. The onset of the rhythm, however, depends upon synchronization of the "clock" by some environmental stimulus such as change in light intensity or tidal level. Such inheritable rhytPhilippine Shell in other activities of mollusks are well known; for example rhytPhilippine Shell in oxygen consumption, feeding and spawning. These rhytPhilippine Shell may be diel or tidal and expectedly would be most developed in inter-tidal mollusks. That these basic metabolic activities are all related is almost certain, but the details of their interaction must still be determined. The mechanism responsible for the alternation of rhytPhilippine Shell such as in the checkerboard pattern of L. pintado is also a mystery. Other such alternating rhytPhilippine Shell are the "wave" or triangulate patterns on many mollusks such as Conus species (K,L,M.N). ne control of this deposition pattern may be enzymatic and depend upon the enzyme reaching a threshold necessary for the production of pigment or calcium carbonate (for example, tyrosinase which catalyzes the reaction producing melanin, or carbonic anhydrase which catalyzes the deposition of calcitun carbonate). Another explanation may be the presence of an inhibitor in the cells producing the pigment, which prevents the development of the pigment in the adjacent cells. This is one of the more interesting problems remaining to be solved.
The adaptive significance of shell ornamentation in many species is probably indirect. As discussed above, the ornamentation is likely a result of the interaction of several biochemical and physiological rhytPhilippine Shell. Selection may actually be acting on one or more of these characteristics rather than on the shell ornamentation itself. That certain rhytPhilippine Shell of activity were adaptive is obvious; for example, the feeding rhythm of littorines wmure [?! -- "where"?] maximum activity is at night and their spawning rhythm correlated with high tides. In the terminology of geneticists, this may result from pleiotropic genes, that is, genes which determines more than one characteristic of the organism. Since the shell ornamentation does reflect biochemical activity of the animal and environmental events, it is a valuable record of their life history.
The next step in deciphering the "code" is to study the effect of certain key environmental factors on the development of the basic pattern. Some of the factors which appear to affect color pattern are temperature, light, submergence and possibly oxygen. In L. picta, the color pattern is extremely variable. Each individual appears to respond to a threshold temperature at which the maximum development of the genetic pattern is "switched on." Above or below this temperature, the pattern is either incompletely developed or absent. Studies on the effect of a range of environmental factors on the developing shell would do much to elucidate the importance of environment in shell ornamentation.
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