New Jersey Scuba Diving

Marine Shellfish

crabby

These animals are lumped together here because they all have hard external shells. Crustaceans and Mollusks are not closely related at all. This is more of a restaurant classification than a scientific one.

American Lobster

Homarus americanus

Size: to 36" and 45 lbs. (record)

Habitat: subtidal to the edge of the continental shelf, in any sheltered spot

Notes:

Lobsters differ from shrimps in having three pairs of clawed legs, the first with very large claws. Southern "Spiny Lobsters" are only distantly related; freshwater crayfish are closer. Lobsters, or "Bugs", are mainly nocturnal, and feed primarily on living or freshly killed food rather than scavenging on carrion, as was once thought. Although they are predominantly solitary creatures, lobsters do have a sort of social life amongst themselves. Males are more aggressive than females and will form pecking orders among individuals in an area. Female lobsters apparently seek the protection of a male when molting, then mate afterward. Lobsters shed their shells once or twice a year, depending mainly on the temperature.

More: American Lobster ...

Crabs

These are all so-called "true crabs".

Crab anatomy
Crab anatomy - Blue Crab

True crabs are crustaceans with extremely reduced tails, which are carried folded under the body. Males are generally larger than females. Presented here are just the most common of many local species. Sizes quoted below are body width. Hermit Crabs are listed elsewhere. They are not closely related.

More: Crabs ...

Snails

x-ray

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 ...

Bivalves

All of these bivalves are filter feeders. The other major group of mollusks is the Gastropods or snails. Squid and octopus ( cephalopods ) are mollusks too, but they don't behave like other mollusks, so I included them elsewhere. Teredos are bivalves that have evolved a worm-like wood-boring habit.

Clam Anatomy
Typical bivalve anatomy

More: Bivalves ...

Decompression Theory

An Explanation of Professor A.A. Buhlmann's ZH-L16 Algorithm

by Paul Chapman

Note to new divers and potential new divers:

This information is presented for general interest. Don't be scared off by what you see here - you don't need to learn any of this to become a safe and competent scuba diver. You will however need to understand dive planning.

The following is a summary of the decompression algorithm described by Dr A.A. Buhlmann in the fourth edition of his book Tauchmedizin ( diving medicine ) published in 1995 ( only in German. ) the book contains a considerable amount of other information and is published by Springer-Verlag ISBN 3-540-58970-8. Rumor has it that at the time of writing ( November 1999 ) an English translation is being prepared for publishing, so hopefully, in due course, this document will become redundant.

The algorithm is simply a "recipe" for modeling the behavior of inert gases, which diffuse in and out of our body tissues when breathed under varying pressures. The intention is that if the recipe models the actual processes in our bodies accurately enough, it can be used to plan dives ( and other pressure exposures ) with a view to avoiding decompression sickness.

More: Decompression Theory ...

Disclaimer:

I make no claim as to the accuracy, validity, or appropriateness of any information found in this website. I will not be responsible for the consequences of any action that is based upon information found here. Scuba diving is an adventure sport, and as always, you alone are responsible for your own safety and well being.

Copyright © 1996-2024 Rich Galiano
unless otherwise noted

Powered by WordPress. No, really.
Cookies blah blah whatever

367 // 224075 // 1397

Printed from njscuba.net