K's Kreature Feature is an educational presentation at our monthly general staff meetings here at the Two Oceans Aquarium, but it’s only right that we extend the knowledge and fun to our readers here on our website. Every month Education Operations Co-ordinator Katja Rockstroh presents a different animal that we have here at the Aquarium and tells our colleagues more about it. Usually she uncovers some rather interesting facts about the various animals she researches. She also makes sure to entertain her co-workers …

The octopus belongs to the class Cephalopoda. This class also includes the cuttlefish (another favourite of mine), the squid, as well as the nautilus (the weirdo of the group).

A nautilus:

Photo courtesy Manuae (uncer licence CC BY-SA 3.0)

Octopuses are divided into two main groups: the Incirrina and the Cirrina. The Incirrina include our common octopus and other more “normal”-looking octopuses, like the blue-ringed octopus, which is tiny, but deadly. And then we have the weirdos again, the Cirrina. The characteristics that set them apart from Incirrina are two fin-like structures on their head, a small, internal shell as well as cirri along the underside of their tentacles.

Some of them are rather adorable, like the dumbo octopus: 

Photo courtesy Mike Vecchione, NOAA (public domain)

Another fascinating Cirrina octopus is the blanket octopus. I would encourage you to google that – it’s like an octopus with a superhero cape. Cephalopoda is a Greek word and literally means “head-feet". The cephalopods do look rather bodiless, with something looking like a head taking up the majority of the body and a tangle of “feet” sprouting from the end. Generally, we refer to arms or tentacles rather than feet.

The word “octopus”, also of Greek origin, is pretty straightforward: eight feet, which is what all octopuses have. The scientific name of the common octopus is Octopus vulgaris. The species name, vulgaris, has nothing to do with the word vulgar. It, in fact, means common. This animal definitely has the most straightforward and logical scientific name ever.

Photo courtesy Albert Kok (public domain) 

Let's settle this once and for all

In terms of what to call more than one octopus, the correct answer is octopuses. An –es ending is the common way to pluralise a word of Greek origin. Many however use octopi as the plural, but this isn’t correct, as that is the common pluralisation of a Latin word. A third and less common plural of octopus is octopodes. All three are acceptable, but since I am a stickler for being correct, I use the term octopuses.

The man who first described the common octopus was Georges Cuvier. He was kind of a Big Deal back in the day. So big that his name is forever carved on the Eiffel Tower along with 71 other scientists and engineers. He was a naturalist, zoologist, comparative anatomist and hailed as the “Father of Palaeontology”. He expanded Linnaeus’ classification by adding the phylum, he believed in catastrophism, established extinction as a fact, identified fossils of the mastodon and megatherium and discovered and identified the Pterodactylus genus. Pterodactyls are those cool flying dinosaurs in Jurassic Park. Basically, this man did a lot for science.

Georges Cuvier. Public domain image  

But back to the common octopus. It is pretty common, since it is found along the shores of almost every continent. Only Australia and Antarctica don’t have the common octopus swimming around their seas. It feeds on other molluscs, like clams and snails, crustaceans, urchins and fish. It in turn is fed on by seals and large predatory fish as well as eels.

Anatomically speaking there are a few interesting points. Firstly, this octopus (and the other cephalopods) has a beak for a mouth. It looks like a parrot’s beak, but the difference is that inside the mouth there is a radula, which is essentially a conveyor belt of teeth. The radula makes it easy to crunch up food.

Squid beak: 

Since the octopus lacks a shell, it can squeeze through any hole that its beak can fit through.

Case in point:

Octopuses also have three hearts. Their blood is blue and is called haemocyanin. It lacks the red blood cells us humans have. This makes haemocyanin very inefficient in carrying oxygen, which has resulted in the octopus requiring three hearts. Two of the hearts are branchial and supply the gills with blood. The third heart delivers blood to the rest of the body.

Octopuses have fascinating yet tiny brains – they are among the most intelligent creatures in the ocean. 

The ability to camouflage themselves, however, is still the most baffling and scientists still do not fully understand how they do it. Apparently the military is even looking into this and how to make uniforms that can change colour according to their environment. Below is a great video that shows just how magical octopuses (and the other cephalopods) are:

They are masters of camouflage, escape artists and just the coolest animals ever. They are also, unofficially, called the "Floppy Floppy Spider of the Sea".

Check out our octopus on your next visit! We rotate our octopuses - one octopus will be with us for a while and then we’ll release it and get another one. 

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