New Jersey Scuba Diving

Oyster Drill

Urosalpinx cinera

Size: to 1"

Habitat: subtidal down to 50 ft

Notes: This little snail uses acid and its rasp-like tongue to drill a neat hole in a bivalve or barnacle victim, then sucks out the contents.

Snails

These creatures are all of the order Gastropoda - having a single, often coiled, shell, as opposed to the bivalves, which have two matching shells. Most snails are hermaphroditic. Also, most snails have a right-hand twist to the shell, although there are exceptions.

Right:
X-ray image of a Channeled Whelk, showing internal structure.

Nudibranchs are a form of snail that has lost its shell, while Corollas and Sea Butterflies are snails that have abandoned not just their shells, but the snail-like existence entirely, swimming up into the water column as plankton.

More: Snails ...

Visibility

I have found no correlation between good visibility and anything else at all. Calm seas certainly don't hurt, but the worst visibility I have ever been in was with a 1-foot surf on the beach. There is however a very good correlation between bad visibility and storms, which is why a single hurricane can end the season.

Other factors which influence visibility are: algae blooms, spawning seasons of some invertebrates, which can fill the water with tiny swimmers, jellyfish ( yes, so many you can't see through them, luckily they don't sting, ) other divers churning up the bottom, and just plain gunk in the water. I don't know how to predict most of these, except to say that if you dive a lot, sooner or later you will see some good visibility. Sometimes in the ocean, the visibility will be different in different depth layers. I have seen the viz go from 3 ft on the way down the anchor line to 20 ft on the wreck.

More: Visibility ...