Is an octopus a fish? Well, that is a reasonable question. After all, where you find an octopus you will also find fish.
Both have the ability to extract oxygen from the water which they then metabolize to live. When you look at them they both have two eyes, a mouth — they both can move across the water. Looking at octopuses and fish through those set of parameters it would seem like they are very similar.
Biggest Difference? Intelligence
The reality of the situation, however, is that an octopus and a fish — although both are sea-dwelling creatures — are not the same type of creature at all. Sure, if you dig far back in time there will be an evolutionary ancestor that octopi and fish have in common. Heck, that common ancestor would also be the last common ancestor that an octopus shares with us humans. That “shared cousin,” however, lived more than 500 million years ago. One of the greatest differentiating characteristics of octopuses is their far more advanced intelligence, as testified in the experiment video above.
So, if an octopus is not a fish, what is it then?
An octopus is a mollusk. Yes, a mollusk — like your common garden snail. To be more specific, an octopus belongs to a unique class of mollusks known as cephalopods. This class includes other creatures such as squid. If you want to get even more specific, the order “octopoda” is the one that all species of octopus belong within the larger cephalopod class.
By understanding how octopi are classified so differently from fish, you will be able to get a clearer understanding of the huge differences between both animals.
While both are animals — therefore both belonging to the same highest classification strata, that being “Animalia” — they immediately branch away from each other in the next-highest strata, the phylum. This is where octopi go down the “mollusk” path and fish down the “chordata” path. To put it in simpler terms, this why an octopus has no bones — no skeleton — it is an invertebrate. A fish has a backbone and a skeleton — it is a vertebrate.
When you look at it that way, you can see why both have two eyes, the ability to extract oxygen from water, etc. They share characteristics which existed in animals dating back much further than octopi and fish. However, once they branched away from each other each animal started developing its own unique set of features. You know, that which makes a fish a fish and an octopus an octopus.
Other key differences between an octopus and fish include:
– Fish have scales, octopi do not.
– Octopi create propulsion with jets of water, fish rely on wave-like movements of their body to create locomotion.
– In terms of intelligence, octopi species demonstrate that they are very intelligent animals.
They are tool builders and problem solvers. Fish, on the other hand, do not display that level of intelligence. While an octopus demonstrates a level of cognition, fish tend to be limited to reacting to immediate stimuli — in other words, octopi are smarter.
