Thursday, August 14, 2008

Periwinkle massacre

Hi everyone, I made an interesting observation the other day on the Nahant beach and I was wondering what you guys think about it.
There is a beach in Nahant called Dog Beach where you are allowed to take your dogs all year round and let them romp on the beach off the leash. This beach is directly across from revere where a bay has been created because of the man made causeway used to drive on and off of the island. I always assumed the beach was not the cleanest because it was basically given to the dogs. 
Walking on the beach yesterday I found thousands and thousands, if not millions, of empty periwinkle shells. I waded through the shallows and for 20 minutes and searched for a live snail but I only found one! Almost all of the empty shells had one small hole "drilled" into the bottom which I assume is the calling card of whatever is praying on the snails. 
The number of empty shells was astounding.I found it slightly disturbing after getting to know periwinkles so intimately through our class.
Does anyone know what is eating them? Does the high mortality rate have anything do to do with the dirty water?


1 comment:

Kasper Family said...

Is it a sandy beach or a rocky beach? My guess is that it is a rocky beach and the predator is Nucella lapillus, the dog whelk. lappilus is a predatory snail that feeds by drilling a hole through the shells of muscles and other snails with its radula. lappilus then pushes its stomach contents into the prey and digests the innards and sucks them all back in. cool, hunh?