World Octopus Day

World Octopus Day is part of International Cephalopod Awareness Days, which take place from October 8–12 each year. Since octopuses have eight arms and squid have eight arms and two tentacles, the holiday week begins on the eighth day of the tenth month. Cephalopods are a class of marine invertebrates. Related to snails and clams, cephalopods have arms and tentacles, three hearts, large brains, and blue blood. This day of the week is dedicated to octopuses!

The name "octopus" comes from the Greek word októpus, which means "eight foot." The animal is from the order Octopoda, of which there are 289 species. Octopuses have eight arms, which more often than not have suction cups at their bottom. The arms have clusters of neurons in them, which allow different arms to do different tasks at the same time. In fact, these neuron clusters may be considered to be brains. Thus, octopuses have nine brains, having a central one that controls their nervous system and one in each arm. If an octopus loses an arm, they are able to grow it back.

Octopuses have a bulbous head and don't have any bones, which allows them to squeeze through tight spaces. They have three hearts: one pumps blood through their organs, and the other two pump blood through their gills. The blood is blue on account of a copper-based protein called hemocyanin. Octopuses are known for their intelligence. They can open jars, they carry around coconut shells and use them as tools, and they are known to escape from aquarium tanks. When a predator arrives, octopuses are able to squirt ink at it. This may blind and confuse the predator and interfere with its ability to smell or taste. Octopuses have other defenses, being able to change their color to blend in with their surroundings. But octopuses themselves are predatory. They are carnivorous, eating animals like fish, sharks, lobsters, shrimp, clams, sharks, and birds.

Octopuses live in oceans, often making their homes in reefs, crevices, and shells near the water's surface, although some live in caves on the ocean floor. They are fast swimmers, blasting off by shooting water out of a tube called a siphon. Still, they usually move by slowly crawling on the ocean floor. They have short lives, living between sixth months and five years, with the larger ones living the longest. Their lifespans are short because they die soon after mating. Females lay around 200,000 to 400,000 eggs, guard them until they hatch, and then the cells in her body begin dying until she dies. The male octopus swims off after mating and dies in a few months' time.

One of the most common octopuses, aptly named the common octopus, grows to about 12 to 36 inches in length and weighs between 6.6 and 22 pounds. The largest is the giant Pacific octopus, which usually is about 16 feet in length and 110 pounds. The largest of these ever recorded was 30 feet long and 600 pounds. The smallest octopus is the octopus wolfi, which is shorter than an inch and weighs less than a gram. Octopuses—big or small, today we celebrate them all!

How to Observe World Octopus Day

• View an octopus at a zoo, at an aquarium, or in the wild.
• Get a pet octopus.
• Watch a television show or movie that features a giant octopus or octopuses.
• Learn about some of the different kinds of octopuses.
• Read a book about octopuses such as Octopus!: The Most Mysterious Creature in the Sea or The Soul of an Octopus: A Surprising Exploration into the Wonder of Consciousness.

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