Anatomy and Physiology of a Squid

Squids have always been thought of to be a complex yet simple cephalopod. Well really they are in the middle of the complexity scale for me. The way they live, eat, breath, reproduce, and much more is simple. So for this assignment I will talk about the very well-known squid. Squids are a part of the cephalopod family (meaning head-footed), which means they have their shells on the inside instead of the outside. They do not have the outer shell like other cephalopods, and the octopus has no inside or outside shell at all, but back to the squid. They are an ocean species and like some fish the live in schools. They are also carnivores, meaning they eat meat. They feed on fish and anything else they can pull into their mouths. Their mouths consist of a horny beak and a radula that acts the way a tongue would. When the squid grabs food with its longest tentacles it is then pushed to the mouth and held by the radula and broken apart with the radula the way our teeth would break up food.

Once the food is ingested it goes into the esophagus where digestive enzymes begin to break down the food on the way to the stomach. Once the nutrients needed are taken out the food then goes into the intestine then on to the anus where it is expelled. Squid only need to eat twice a day to sustain it. Although squid like any other living thing need to eat to live, they also have to have a way to hide, escape, and protect itself. So we now move on to what it most well known about squids, and that is that the squirt ink. Squid have an ink sac that is attached to their anus. When freighted they release this ink and it not only distracts the predator but also causes their eyes to become irritated. This is a very good defense for squid but it is not the only defense they have. Squid like octopi have the ability to change colors to mimic their surroundings as a way to hide. If that fails then they can propel themselves out of danger. Located in the mantel of the squid are syphon’s that the use to expel water and propel them backwards.

When being propelled they also use fins on the top of the outer mantel used to help with direction and steadiness. These syphon’s serve another purpose as well, like their ability to breath. Along with these siphons the squid has gills under the mantle. These gills act much like the gills on a fish and allow the squid to pull oxygen from the water. Well while knowing all this is great and ill, the top thing about a squid is the binocular vision. Normal cephalopods have monocular vision, meaning they only see from one eye. This is opposite with squid. They have two eyes, one smaller than the other. Their eyes are very similar to our eyes as well. They can see color and are light sensitive as well. This sensitivity to light helps them determine their souroundings. They also have the ability to see images clearly. I find this to be amazing especially being an underwater animal. In conclusion, while I love to eat and use squid as bait for fishing, they are truly extrodenary.