Nature Blog Network

Thursday, September 3, 2009

Channeled Whelk with Egg Cases

Family friends bought us passes for Project Oceanology's Enviro Lab cruises at an auction this summer, and finally, as the summer draws to a close, we were able to take advantage of them. Project O is an outreach center that focuses on marine science and environmental awareness especially of the Long Island Sound ecosystem. Their Enviro Lab boats are equipped with a small sample trawl, water quality samplers and sediment samplers. I had been on the Enviro Lab boats with classes from the Marine Science undergraduate program at Avery Point (Project O is located on the Avery Point Campus).

For Johann and Tammy it was a new and exciting adventure. Johann's favorite part was examining the results of the benthic sample trawl. After seeing the Mystic Whaler (Which chanteyman extraordinaire Geoff Kaufman often sails aboard) he was inspired to sing a round of "Donkey Riding" as he reeled in the line from the trawl. The fun really started when he got to get really hands on with the samples helping quickly sort the haul and get all the animals into the large wet tanks. In the haul were a dozen Scup (Stenotomus chrysops), several Sea Robin (Prionotus carolinus), some Atlantic Moonfish juveniles (Selene setapinnis), what looked like a small striped bass (I didn't get to see it but that was the description), a feisty female little skate (Leucoraja erinacea) and a spotted hake (Urophycis regia).

While there was quite a number of vertebrates in the haul, there were far more inverts brought up. Among the inverts there were in excess of a hundred spider crabs (Libinia emarginata), two lobster (Homarus americanus,)(both female), two European Green Crabs (Carcinus maenas), one Jonah Crab (Cancer borealis), several broad-clawed hermit crabs (Pagurus pollicaris) and one male Horseshoe crab (Limulus polyphemus). Molluscs were well represented as well with many mud snails (Nassarius obsoletus) and slipper shells (Crepidula fornicata)as well as a half dozen loligo squid.

The real prize though was this female channeled whelk (Busycotypus canaliculatus formerly Busycon canaliculatus). Johann spotted her and pointed out the fact she was currently "laying" and egg case string. Soon after the animals were sorted into the tanks, the guide showed the whelk and explained the egg case string to the guests, then she carefully (more or less) dropped the whelk back into the sound.

The main reproductive time for the channeled whelks is the fall. Egg strings like the one this lady is laying will consist of 40-160 or more egg cases all joined by a tough leathery string. Each case may have as many as 100 eggs inside, though the average number of eggs per case is closer to 40. Not all the eggs in each case are fertilized though and the unfertilized eggs serve as food for the young whelks which emerge from the cases as miniature adults.

There is a small fishery for whelks here in the Long Island Sound, mostly sold in Italian markets as scungili. Unfortunately the most common bait used is chopped up horseshoe crab.