Let’s start by saying that Octopuses probably aren’t aliens. That being said, these creatures have qualities that are certainly alien to us. For example, the octopus has three hearts and a brain that encompasses its entire body. And, almost disturbingly, octopus tentacles can move on their own.
Most people look at octopus tentacles and think there’s either something neat or something seriously off about them. They’re undoubtedly one of the most fascinating body parts in the animal kingdom. Let’s take a look at them…
The Weird Biology of Octopus Suction Cups
According to researchers, octopus tentacles and biology aren’t necessarily governed by an octopus’s central brain. Each suction cup has thousands of receptors on it that allow it to experience the world. The suction cups can even taste and smell their surroundings.
Due to the number of nerves in the suction cups, they’re hundreds of times more sensitive than a human finger. These nerves also form clusters that behave as tiny little brains for each.
These clusters tell the suction cups when and how to move. In this way, each one can grab objects without the brain’s help. They also taste things to determine if objects are food. If something is food, one suction cup will tell the rest to move it up the line into the octopus’s hungry mouth. This is an independent chain reaction from one suction cup to the next. No brain needed.
To put this into perspective: Our fastest immediate reactions have to send impulses from our fingertips to our spine. Then the spine has to send an impulse back, telling us to move. And these reactions are rare. Think of touching a hot frying pan.
Our second fastest reaction requires our nerves to pass signals all the way to our hypothalamus. This happens during “muscle memory responses.” The octopus, however, only has to send signals in fractions of an inch to bring food to its mouth. Amazing.
Why Octopus Tentacles (Arms) Evolved to be Independent
The reason octopus tentacles evolved to be independent has to do with the evolution of the creature’s widespread brain. Researchers believe this served an evolutionary advantage to aquatic life. Much like the pistol shrimp’s ability to generate a blast from its claw. They didn’t evolve simply because they’re interesting.
Some octopuses tend to live in deep environments, where light from the atmosphere barely reaches. Even those in shallower areas hunt and hide in dark crevasses. Either way, they spend a lot of time outside of light’s reach.
The sensory abilities of the suction cups along an octopus’s arm come in handy in these dark places. When the tentacle can sense prey, the brain doesn’t need to see it. When it can feel shape, the octopus can get a “foothold” without thinking about it.
The Boneless Biology of the Octopus Tentacle
It’s common knowledge that an octopus doesn’t have bones and neither do its tentacles. But most people don’t actually understand how this works.
Octopus tentacles still have to keep form, move, and maintain strength. For us humans, our bones provide structure. They also serve as the attachment points for our muscles so we can create force when squeezing against them. That’s the only way we can pick things up or manipulate our surroundings.
The tentacles of an octopus, however, are made up of dense muscle tissue. The muscles produce force by contracting against each other. As well as by creating internal pressure. Combine this with the sectioned nerves in octopus tentacles, and they can produce force in every direction. This also means octopus tentacles can move in ways our bodies can’t. Up, down, left, right, etc. They can even twist.
Since tentacles are boneless, they can also compress like a snake squeezing through a hole. Sure, the entire octopus body can do this, but we’re here to talk about tentacles.
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Octopus Tentacles Can Live After Death… For a Little While
The alien truth about octopus tentacles includes their ability to live without the octopus’s brain. In essence, these appendages still function for a while when they’re detached from the octopus’s body.
Since the suction cups search for food on their own, they’ll continue looking without an octopus mind telling them what to do. They’ll probe and taste. And then, they’ll pass objects toward the octopus’s mouth. Except that mouth is no longer in the vicinity.
This causes the octopus tentacle to crawl around a surface. In truth, the tentacle thinks it’s passing food along, but in reality, it’s moving itself across objects. You can see this in videos of people eating cut-up pieces of raw octopus. Like this one, for example.
Of course, without a way to breathe or eat, the octopus tentacles will die eventually. But until they do, they’ll move about your plate. You probably shouldn’t eat them though, since living tentacles can stick inside your throat. They’ve even suffocated poeple in this way, as Business Insider points out.
Octopus Tentacles are also Reproductive Organs
One tentacle serves a rather unique purpose for the male octopus: Reproduction.
The reproductive organ of a male octopus is a special tentacle or arm, known as the hectocotylus. This isn’t an extra tentacle, but rather one of eight arms. The male will insert this arm into the mantle cavity of a female to inject sperm, but this can be dangerous.
Many species of octopus have a larger female and smaller male. To reach the body cavity, the male has to get close. Unfortunately for him, many octopuses are cannibalistic. He’s likely to lose an arm or even his life in the process of mating.
Octopus Tentacles aren’t Really Tentacles – They’re Arms
We know, we know – octopus tentacles aren’t tentacles. Many people wrongly call these appendages tentacles, but they’re actually arms.
Here’s the difference (and it’s simple): For cephalopods, an arm has suction cups along its entire length. Whereas a tentacle only has suction cups near the end.
Don’t worry, we knew someone was going to correct this, so we thought we should do it ourselves. But thanks for looking out!
