Octopus Vulgaris

(The Common Octopus)

By: Alek

Introduction:

Octopus vulgaris, or the common octopus, is located world wide in many coastal waters. These waters are generally tropical or semi-tropical, and tend to be as shallow as 200 meters. Octopus vulgaris is a member of the Mollusca phylum, resides under the class Cephalopoda, and is in the Octopoda order. The common octopus has many close relatives, which include the many species of octopuses, squid, and cuttlefish. Octopus vulgaris is believed by taxonomists to contain a number of related sister species. However they have not yet decided how to split the species.

The common octopus can reach a length of about 24-36 inches in length for both male and female. Both genders live for a short time of 12 to 18 months, females maybe even for a shorter amount of time due to offspring. These octopuses are nocturnal predators who are known primarily to feed crustaceans, bivalves, and gastropods. Octopus vulgaris is both a merciless predator, and tasty prey… Both to other marine animals, and humans alike! The common octopus is widely used in the commercial food industry for many cuisine dishes. YUUUMMMMMMYYYY!

Anatomy:

One aspect to note about these cephalopods is that they have very well developed nervous systems, and the most advanced and complex brains of all the invertebrates. Also they have very elaborate eyes with a cornea, lens, chambers, and a retina, similar to those of the vertebrates; however they cannot perceive color. Not shown above is the radula. The radula is a tongue-like organ coated in “teeth” that helps with shredding tissue of prey.

Form and Function:

The common octopus’s arms are used in food capture and handling and have a complex musculature, suction cups, and are capable of delicate movements. Using these arms, the octopus is capable of high-speed maneuvers and is able to swiftly seize prey and bring it to the mouth. An unknown factor of octopuses as well as cuttlefish is they have salivary glands that produce venom that helps immobilize prey. Once the prey is slightly paralyzed, the octopuses’ beaklike jaws grab hold of the prey, and the radula (aforementioned) tears off pieces of the prey’s flesh. Digestion is extracellular and occurs in the stomach and the cecum. Wastes are then expelled through the anus.

Octopus vulgaris reproduces sexually. Before sexual activity, the male octopus often undergoes color displays directed towards females and against rival males. The spermatozoa in males are encased in spermatophores and stored in the gonad sac. During copulation the male uses one of its arms to pluck a spermatophore from its mantle cavity, and inserts it into the female’s mantle cavity. The female octopuses tend their eggs and often die because of it.

ctopuses are preyed upon by a select few of other organisms. For example pinnipeds, barracuda, seals, and eels all enjoy a good cephalopod snack. The octopus has primary and secondary defenses for these predators. The primary defense it possesses, which is nearly full proof, is “crypsis.” Crypsis is the term applied to the octopuses amazing ability to camouflage, and even mimic other animals, with the entirety of its exterior. Octopus vulgaris possesses skin cells called chromatophores that can completely adjust color, design, and even texture to fit their environment. The octopus’s secondary defense is its flight and ink technique. When faced with a last resort, the octopus will release and cloud of ink as a smoke screen for a quick getaway.

Impact on Humanity:

Sadly, octopus vulgaris is a large part of the worlds fishing industry with an average of 20,000 to 100,000 tons caught per year. The common octopus accounts for around 50 percent of all octopus catch world wide. In countries such as Japan, Greece, and the region of Northwest Africa particularly, octopus is one of the main seafoods on the menu. Their ink is even used in ice cream!!

Journal Review:

http://www.bioone.org/doi/abs/10.2983/035.028.0326

This journal discussed an experiment in which scientists fed octopus vulgaris stationed in two separate tanks (low and high density) only mackerel as opposed to its usual diet. The studies showed that the octopuses had increased body weight as opposed to their usual diet. The octopuses were at a 100 percent survival rate in a low-density tank. However, results did show that the diet caused an increased aggressiveness in the octopuses that were in the high-density tank, which led to some fatalities among subjects. It was then proposed that as long as supplied with crustaceans as well, this would be less likely to occur.

Works Cited

Pierce, M.L. (n.d.). Marine invertabrates of bermuda. Retrieved from http://www.thecephalopodpage.org/MarineInvertebrateZoology/Octopusvulgaris.html#Taxonomy

Pham, C.K. (2009). Growth and mortality of common octopus (octopus vulgaris) fed a monospecific fish diet. Journal of Shellfish Research, 1. Retrieved from http://www.bioone.org/doi/abs/10.2983/035.028.0326

Peoples, Trust. (2009). The common octpus. Retrieved from http://www.ypte.org.uk/animal/octopus-common-/148

The Big Zoo, . (2010). Common octopus (octopus vulgaris). Retrieved from http://www.thebigzoo.com/Animals/Common_Octopus.asp