New Jersey Scuba Diving

Sharks - Dogfishes

Smooth Dogfish
Most of these sharks are in more danger
from us than we are from them.
Real sharks are ashamed of them.

"Dogfish" is a generic name for a large number of small, generally harmless, and unaggressive sharks, not all of which are very closely related. Smooth Dogfishes are related to Tiger, Bull, and other Requiem Sharks, while Spiny Dogfishes are in a completely different group, more closely related to Angel Sharks. Compare these with the unrelated Chain Dogfish, a "Cat" shark. Sandbar sharks have nothing in common with the others here, except their small size. None of these little sharks is really dangerous, although any of them could give a good bite if provoked. Generally, they will avoid you.

Spiny Dogfish

Spiny Dogfish

Spiny Dogfish
Squalus acanthias

Size:
to 3ft (male)
to 4 ft (female)

Habitat:
cool coastal waters, midwater, and bottom, but seldom at the surface

Notes:

The Spiny Dogfish has two distinguishing features: rows of small white dots that run along its sides, and a sharp spine that is found in front of each of its two dorsal fins. The spines of the Spiny Dogfish are formed from material much like that of our teeth. Other distinguishing features include the lack of an anal fin, and the rounded, un-notched tail, unlike the Smooth Dogfish. In the water, the white spots are the thing most likely to jump out at you for identification, although they fade away in some older individuals.

More: Spiny Dogfish ...

Smooth Dogfish

Smooth Dogfish

Smooth Dogfish
Mustelus canis

Size:
to 4ft (male)
to 5 ft (female)

Habitat:
shallow coastal waters, in depths 30 ft and below.

Notes:

Smooth Dogfish are tannish-gray, slate-gray, or brown above. The lower sides and belly are white, grayish-white, or yellow. A sooty spot is often found near the tip of the upper lobe of the caudal fin. The species is distributed from New Brunswick, Canada, to Uruguay, and inhabits the bottoms of estuaries and coastal waters out to a depth of about 650 feet. During the spring and summer, most of the sharks are found in waters less than 60 feet deep.

More: Smooth Dogfish ...

Chain Dogfish

Chain Dogfish

Scyliorhinus retifer

Size:
to 18"

Habitat:
open ocean bottoms, deep

Notes:
This is a harmless little Cat shark that is found on deep wrecks beyond 130 ft.

More: Chain Dogfish ...

Atlantic Angel Shark

Angel Shark

Squatina dumerili

Size: to 5 ft

Habitat: shallow coastal waters to extreme depths

Notes:
Angel Sharks are ambush predators, much like Goosefish. They are generally passive creatures but can bite viciously if provoked. They seem to be intermediate between sharks and rays, and are actually more closely related to Spiny Dogfish than anything else, despite appearances.

More: Atlantic Angel Shark ...

Sandbar (Brown) Shark

Sandbar (Brown) Shark

Carcharhinus plumbeus

Size:
to 6 ft

The Sandbar Shark is the commonest inshore shark in New Jersey waters.

Sandbar (Brown) Shark

Most people are familiar with Peter Benchley's thrilling novel Jaws or one of the movies it has inspired. The image of a giant shark terrorizing a small resort community is hard to forget. After all, the idea of predators ( in this case, people ) becoming prey realizes one of our most primal fears. It also makes for exciting reading or viewing.

More: Sandbar (Brown) Shark ...

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 © 1996-2026 Rich Galiano
unless otherwise noted

Powered by WordPress. No, really.

This website is 100% ad and AI-free

798 // 601837 // 1267

Printed from njscuba.net