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New Jersey Scuba Diving

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New Jersey Scuba Diving

Squids & Octopus

Invertebrates

Squids and octopuses are cephalopods ( Latin: "head-foots". ) They are extremely evolved mollusks. The shell is internalized as a support structure in squids, or completely absent, as in octopii. There are probably more squids than fish in the sea, both by numbers and by mass.


Longfin Squid

Squids & Octopus

Longfin Squid Loligo pealei

Size: to 17"

Habitat: Generally deep waters, but moves inshore in the summer. I have seen small ones at depths of 50-70 ft and babies in the rivers.

Notes:

Longfin SquidThe squid is a mollusk, related to snails and clams. These animals travel in schools, swimming backwards by jet propulsion. Small specimens are nearly transparent except for the eyes. Tropical squids can show considerable intelligence and curiosity, but northern versions are, well, just stupid. I have seen huge schools of small transparent squids offshore, just their eyes visible, like black marbles. In the rivers, I have seen small schools of purple squids, and tiny colorless babies drifting in the current. All are predatory.

Longfin Squid anatomy

Longfin Squid
Longfin Squid in the wild

Longfin Squid
Most people only ever get to see them like this ...

Longfin Squid
... or this.

Longfin Squid eggs
Squids spawn en masse. Each finger in these egg clusters was produced by a single female. Northern Squid live less than a year, and die after spawning. Better not to be a squid ! ( Mohawk )


Common Atlantic Octopus

Squids & Octopus

Common Atlantic Octopus Octopus vulgaris

Size: see below

Habitat: rocks and coral reefs, all depths

Notes:

The Common Octopus is the most-studied of all octopus species. Its natural range extends from the Mediterranean Sea and the southern coast of England to at least Senegal in Africa, as well as the Azores, Canary Islands, and Cape Verde Islands. In the western Atlantic, it ranges from Texas and Florida to New England, although uncommon in colder northern waters. Typical habitat is rocks and coral reefs. Young are planktonic, and lifespan is only 12-18 months.

O. vulgaris grows to 25 cm in mantle length with arms up to 1 m long. They can weigh up to 20 pounds, although they are usually much smaller. O. vulgaris is caught by bottom trawls on a huge scale off the northwestern coast of Africa. More than 20,000 tons are harvested annually.

Common Atlantic Octopus

The Common Octopus hunts at dusk. Crabs, lobsters, and bivalve mollusks are preferred, although the octopus will eat almost anything it can catch. It is able to change color to blend in with its surroundings, and is able to jump upon any unwary prey that strays across its path. The prey is paralyzed by a nerve poison, which the octopus secretes, and the octopus is able to grasp its prey using its powerful tentacles with their two rows of suckers. If the victim is a shelled mollusc, the octopus uses its beak to punch a hole in the shell before sucking out the fleshy contents.

Training experiments have shown that the Common Octopus can distinguish the brightness, size, shape, and horizontal or vertical orientation of objects. They are intelligent enough to learn how to unscrew a jar and are known to raid lobster traps. O. vulgaris is the only non-vertebrate animal protected by the Animals ( Scientific Procedures) Act 1986 in the UK; they were included due to their high intelligence. Octopuses are venomous, and can and will bite with a sharp hard beak, so handle with care.

The illustrations here are just examples, as this creature can change color, pattern, reflectivity and polarization, texture, and shape at will to blend in with its surroundings. Most cephalopods are colorblind, although sensitive to polarization. Apparently the skin itself has receptors that do the color-matching. The entire nervous system is much more distributed than ours - the arms are semi-autonomous, the central brain contols them in an overall way, with little sensory feedback.

Common Atlantic Octopus
Common Atlantic Octopus
Octopus caught on the Cape May Artificial Reef


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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 © 1996-2016 Rich Galiano
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