Images by Paul Callomon
Anyone can be a naturalist. On the Academy blog, our scientists and experts share their knowledge to help you explore the natural world around you. Paul Callomon, collection manager for malacology, suggests you keep an eye out for whelks—and their egg cases—on your next trip to the shore this summer.
The channeled whelk, Busycotypus canaliculatus, is one of the most common shells on the beaches of New Jersey. It is also one of the largest, occasionally reaching nine inches in length. The channeled whelk and its relative, the knobbed whelk, are carnivores that prey on clams and other bivalve mollusks. They will happily eat carrion, too, and can therefore be easily fished using baited traps. The meat is a popular food item in the Far East.
Walking the Jersey beaches, you can sometimes find the long, twisted rope-like object seen here. This is the channeled whelk’s egg case, a “necklace” of flat, disk-shaped capsules, each containing many embryos. The mother whelk buries one end of the rope in the mud, to prevent it from being washed away. After the embryos mature, they emerge through a special hatch in the capsule wall and crawl away. One rope can house thousands of embryos, but the fiercely competitive sea bed environment means that few will make it to adulthood.
Though the natural color of most whelk shells is tan or orange, you will sometimes find one that is gray or black. This change of color takes place when an empty shell is covered by shifting sand on the sea bed. As the sediment above the shell thickens, dark-colored minerals in the sand gradually leach into it and begin the process of fossilization. Normally this happens far offshore and out of sight, but nowadays thousands of tons of sand are dredged up each spring and dumped back onto New Jersey beaches to offset the effects of erosion. Millions of blackened shells of all kinds are carried ashore with the sand for beach goers to discover.
This article originally appeared in the Summer 2011 edition of Academy Frontiers.
Paul, I loved your article! Very informative and fun to read. This is a great way to engage our Academy audience and community. Thanks for your good work to research and write this piece.
How much does the all dark black shell cost?