The Three Sisters #05: Violet marine gastropods Intense cool colours, especially violet and blue, are generally uncommon in marine gastropod shells. Species which show vivid violet hue have therefore been highly favoured and prized by collectors throughout the shell collecting history. The most famous such rarity is perhaps the Violet Spider Conch, Ophioglossolambis violacea (Swainson, 1821), endemic to Mauritius which uniquely among strombids has a vivid violet aperture and has been, and still is, regarded as one of the most desirable shells of all. Similarly, the uncommon Melapium elatum (Schubert & Wagner, 1829) from south and east Africa has been coveted for its deep purple columellar. Not all violet marine gastropods are rare, however, and most members of the pelagic Purple Snails of family Janthinidae are wholly or partially intensely purple. This makes them one of the best known purple gastropods, yet they are abundant and arrive on beaches in large numbers especially large storms; becoming a favourite for beach-combers and shell collectors alike. When hearing violet and snails many may associate with the famous ancient purple dyes such as the Tyrian purple. Although these dyes originate from purple mucus of marine gastropods, the shell of Bolinus brandaris (Linnaeus, 1758) the main species producing them is not vividly violet (though Hexaplex trunculus (Linnaeus, 1758), another source species, often carry purple hues especially inside the aperture). Some other species also consistently showing purple colours include the Carnelian Cowrie Lyncina carneola (Linnaeus, 1758) and Coralliophila radula (A. Adams, 1855), among others. Violet is more common in bivalves, for example some members of families Pectinidae (such as Mimachlamys crassicostata (Sowerby II, 1842)); Mytilidae (such as Mytilus edulis Linnaeus, 1758); Pharidae (such as Siliqua pulchella Dunker, 1852); Psammobiidae (Hiatula atrata (Reeve, 1857)) and many others produce intensely purple shells. Violet hues are also seen among landsnails, for example the extremely colourful genera Polymita and Liguus. Left to right: Melapium elatum (Schubert & Wagner, 1829) STREPSIDURIDAE -100~150m, Trawled off Inhambane, South Africa, 40.1mm Ophioglossolambis violacea (Swainson, 1821) STROMBIDAE Saint Brandon, Mauritius, 118.2mm Janthina pallida Thompson, 1840 JANTHINIDAE On beach after storm, Busselton, Australia, 33mm
Posted on: Fri, 15 Aug 2014 11:47:27 +0000
Trending Topics
Recently Viewed Topics
© 2015