Oliva irisans Lamarck, 1811
Olives are one of the most fascinating families of shells to collect. Although any olive is immediately recognizable, these glossy shells come in an infinite variety of color patterns, shape and size. Here in Florida, olives are one of the easier shells for the beginner to collect as they often live in shallow water, burrowed in the sand. They are scavengers and predators. They are communal and will share a meal with others. Empty shells are common in beach drift.
Olives present challenges. Scientists disagree on the nomenclature and the name that appears in the dealers list and shell books is often different than the currently accepted scientific name. These five specimens can often be found identified as Oliva lignaria Marrat, 1868. Recently it was decided that lignaria is a synonym for a different shell named Oliva ornata Marrat 1867. Oliva ornata may not even be a species, itself a variety of Oliva irisans Lamarck 1811 which is now the currently accepted name. Hold on, these may also be identified instead as Oliva concinna, Marrat, 1870. No concinna is a form based on structure of irisans – Oliva irisans forma concinna Marrat 1870. Very confusing! To become an expert on olive identification one must learn all about filament channels, columellar callosity, and fasciole. It gets technical! The color varieties too all have been named, such as Oliva irisans forma oldi Zeigler 1969 which is the heavily mottled shell.
These shells were donated from the collection of Richard Kent. They came from Australia, Indonesia and the Philippines. It took much time and searching to assemble a couple of color sets. Interestingly, the common plain pattern shells are now hard to obtain as only the scarcer color patterns are collected by divers as these bring the highest prices. ps: still searching for the very rare albino variation.