Cephalopod Research Paper

There are many marine animals that are classified as cephalopods. A cephalopod is an aquatic animal that has bilateral body symmetry, a set of tentacles or arms, and a distinctive head. Cephalopods are the most intelligent and the most mobile of all the molluscs. There are many types of cephalopods: differing in size, shape, and their living habits. Two types of cephalopods are squid and octopi. Although, squid and octopi are both classified as cephalopods, they have many differences. Squid and octopi differ in physical features, living environment, lifespan, behavior, and much more.

The squid has slightly different physical features than the octopus. A squid has eight arms, separated in pairs of two and attached at the bottom of its triangular-shaped head. They have two eyes, one on either side of its head. These eyes are like a camera lens; by positioning the lenses in their eyes, they can focus on something. They cannot see color, but they can see in the dark. Squids have eight arms and two tentacles that are longer than the arms. Suckers and sucker rings, also known as hooks, cover the bottom of the squids' arms and tentacles. Squids also have two fins on the side of their head, mainly used to steer while
swimming. Although, squids do not have a backbone, they have a similar structure called a pen. A squid pen is flexible; it serves purpose as the squid’s shell by supporting the organs and tissue. Some may think the fins are what makes the squid such a strong swimmer, but that is false. The squid is able to move by sucking up water into its mantle cavity, then pushing it out through a funnel. The water being pushed out of the funnel and acts like a jet and shoots the squid in any direction at very high speeds.

Male squids have an arm that is shorter than the rest. This arm has a copulatory pad instead of suckers. The male squid uses this arm to insert spermatophores into the female squid’s mantle. The female squids mantle has an ink sac that will protect the eggs once produced. The female squid can produce thousands of eggs. Many times, squids are only able to mate one time before their death. Squids life span stretches from nine months to five years. This time span is so vast because shortly after the male squid mates, it dies. While the female squid usually only lives long enough to care for her eggs. Once the female squids’ eggs hatch the she dies. The baby squids are left to learn, grow, and survive all by themselves immediately after birth. Although they don’t have a parent to teach them, they are still considered one of the most intelligent invertebrates.

Squids travel alone, but they can also travel in schools. They mainly live in the open ocean and feed on crabs, fish, shrimp and other squids. They capture their prey by grasping it with their arms and tearing it to bite sized pieces. They are able to rip their prey apart because their mouth has a strong, horny beak made mostly of organic material and chitin inside. Also inside their mouth, they have what’s called a radula. A radula is the squids tongue like organ, it is very rough. Squids have three hearts, one systematic heart that pumps the blood (which is blue) throughout its body, and two branchial hearts.

An octopus is also considered a cephalopod, although it differs from the squid in many ways. Attached to the octopuses' round head is eight arms/tentacles. The arms have one to two rows of suckers at the end. Octopi lack any kind of backbone; they have a soft body which allows them to fit into small/tight places. Without a hard structure, they are still able to move swiftly throughout the ocean. They move around by using jet propulsion; they draw water into their mantle and force it out in narrow siphon, moving the octopus backwards in any given direction. An octopuses’ body is covered with chromatophore, allowing the octopus to camouflage itself and blend into its surroundings. Chromatophore is a color changing cell that is able to reflect light in such a way that it picks up pigment from its surroundings.

Octopi vary in size; they can be as small as one centimeter or they can grow to be larger than 5 meters. To mate the male octopus inserts its special arm, known as a hectocotylus into the female octopus’ mantle, shooting spermatophores into it. Some octopi can detach this arm and give it to the female. The male octopus dies not long after mating. The female squid will produce and then care for her eggs until they hatch. Once hatched the baby octopi are by themselves, and the mother passes away.

Octopi capture their prey by injecting it with their venom. (All octopi are venomous, but only one is known to be fatal to humans.) After injecting it with venom, they use their strong beak and radula to devour their prey. They mainly feed on Polychaeta worm, crabs, molluscs such as clams, and fish.

Squid and Octopi care both classified as clephalopods; squids from the order teuthida, and octopi from the order octopoda.
They share many of the same features, lifestyles, and behaviors. The squid and the octopus share similar mating styles as well as the time of passing. Both the male octopus and the male squid die shortly after mating, while both the female octopus and female squid stay alive to care for their eggs, then pass. The squid and octopus both have three hearts, a systematic heart, and two branchial hearts that surround the systematic. Although, they have many similarities they have a lot of differences. Differing in where they live, physical features, lifespan, and more. Both are amazing and intelligent
creatures.