Squid Dissection
Background Information
There are more than 300 species of squid identified throughout the world, in the deeper parts of freshwater and saltwater. All are characterized by soft, elongated, tubular bodies, compact heads, and ten arms. Two of those arms are longer and have suckers with horned rings used for catching prey. They range greatly in size, the smallest being ¾ inch and the largest being 65 feet.
Like fish, squid use gills on the sides of their heads to process needed oxygen from the water. Their heads also feature large eyes on both sides. These eyes are believed to be as complex as those of humans. They do, after all, need to watch out for predators in the dark reaches of the ocean, almost near the ocean floor. Squid can be considered the prey of many other animals because of their soft bodies.
When threatened, squids will squirt out a jet-black ink. If they’re not so lucky, other animals will digest the entirety of the squid except for its hard beak. The inside of the squid is also composed of a tough, horny material.
Major Internal and External Anatomy
Mouth: consumes small organisms that will travel to the esophagus to be digested
Beak: the buccal mass is the muscular
casing around the beak; tears
food into small pieces; attached
to the esophagus.
Gill heart: also called a brachial heart; one is located at the base of each gill to pump blood from the body to the gills
Gill: a respiratory
organ that exchanges oxygen and carbon dioxide between the blood and the sea water
Pen: the remnant of the shell that is found within the
mantle on the dorsal side; functions
as support for the mantle; colored by a dark ink
Stomach: small oval structure located over the caecum; breaks down food
Incision Guide
On the dorsal side of the squid, begin the incision on the superior portion and down the medial plane to the inferior portion.
Remove the beak by cutting along the highlighted circle.
Open the flaps you've created and view the pen, gills, gill hearts, and stomach.
If you flip over the main portion of the squid, you can view the vein that runs from proximal to distal ends.
If you're just curious, you may want to cut the flaplike areas off and cut them in half to reveal the veins running through them. Proceed to cut the rest of the squid to find the remaining parts.
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