Alaskan Super Mollusk

Alaskans, being modest by nature, are not inclined to brag about Alaska's being more than twice as big as Texas, its giant mosquitos, strawberries and cabbages or all the other reasons why Alaska is better than other places. Because of this modesty, it hurts to claim that even Alaska's snails are bigger than those of other places.

As proof, I offer the accompanying photograph of a giant ammonite found at Cape Douglas on Kamishak Bay. More than 16 inches in diameter, this fine specimen is in storage at the University of Alaska Museum.

The person versed in such matters will recognize that one reason it hurts to claim this photo as proof of Alaska's giant snail population is that an ammonite is not really a snail. Though both are of the same Mollusca phylum, snails are gastropods (stomach-footed) and ammonites are cephalopods (head-footed). Another reason is that all ammonites died out about 70 million years ago. And, as huge as this Alaskan ammonite is, even larger ones--more than six feet across--have been found in Germany.

Ammonites and many other forms of life such as the dinosaurs died out at the end of the Cretaceous period, for reasons that seem mysterious. This was the time when the highlands of Alaska were starting to rise from the sea, an era that one scientist called "The time of the great dying."

One suggestion for the death of the ammonites is that they lost their sense of symmetry and developed into bizarre, useless shapes. Evidence of this view is found in the curious crenate (leaf-like) shapes seen on the fossil remains. These are the remnants of what were once plate-like septa dividing up the ammonites' shell into cavities (like its only living relative, the pearly nautilus, the animal lived in the outermost cavity of the spiraled-up shell). It is thought that some strange twist of evolutionary fate caused the septa to change from simple flat walls to the grotesque shapes seen in the photograph.