SHELL OF THE MONTH SEPTEMBER 2012

A conch is a conch believed the great naturalist Linnaeus, so in 1758 he classified our shell as Strombus Lambis. This didn’t sit well with his followers who observed a group of conchs with claw like extensions that they believed deserved their own genus.  Lamark in 1799 renamed our shell Pterocera Lambis – from the Greek, pteron, wing and keras, a horn. This is in my opinion a fantastic name. Unfortunately in 1798 Roding was also reclassifying the spider conchs and beat Lamark to the punch, hence ourshell is known today by the boring name Lambis lambis, Linnaeus 1758.
The distinctive feature of the spider conchs is that the mantle in the adult expands into a series of long finger-like processes each of which secretes a calcareous process or “claw” that give the shell its most distinctive appearance.
Lambis lambis is one of the few shells that exhibit sexual dimorphism. First, the females grow to almost twice the size of the males. Second, the claws point out in opposite directions, with the females longer and more finely developed. Third, they are different in color. The female tends to be a solid drab tan. The male mottled tan and cream while in some populations, as this one, a rich chocolate making it a most stunning shell.
It is interesting to note that the only other member in this small genus to exhibit sexual dimorphism is Lambis chiragra, Linnaeus 1758. The spider conchs, also known as scorpion shells, live in coral reef areas. They can be found in littoral and sublittoral zones, in tidal pools and low tide levels to a depth of around 25 meters. They are herbvivores.
Our specimen comes complete with the operculum, is from the Philippines and was donated from the collection of Richard Kent