Now that biologists have really started to explore the biology, habits, and characteristics of the octopus, we’re starting to fully grasp how much of a natural marvel these eight armed
Multiple Octopus are Called …
If you’re like me and have always referred to multiple octopus as octopi, your grammar needs a tune up. Apparently, this is no longer the correct word. According to current grammar rules, the proper word for more than one octopus is actually octopuses. The reason for the change has something to do with the fact that Latin version of octopi ends in a Greek word, something that’s considered taboo. So, from now until someone decides to play around with grammatical rules again, multiple octopus are octopuses.
Their Ink is Deadly
Most people know that when threatened, most species of octopuses shoot out a jet of ink that makes it impossible to see the octopus. The ink is What’s less well known is that the ink is poisonous, even to the octopus itself if the animal isn’t quick about moving out of the ink stained water.
It’s worth noting that not octopus species produce ink and are forced to rely on other defense methods.
They See with Their Skin … Maybe
Even though the structure, shape, and function of the octopus eye is startling similar to that of human eyes, a majority of the scientific community believes that octopuses are color blind, which makes their ability to accurately camouflage themselves truly remarkable. According to Katherine Harmon Courage in her book Octopus!, the scientific community now believes that it’s possible that these fascinating invertebrates have something in their skin that picks up visual cues, allowing the skin to “see” the color and texture it needs to mimic in order to be effectively camouflaged against a rock/plant/sea floor.
How did scientists each this somewhat startling hypothesis? Well the first and most obvious clue was the speed and accuracy with which an octopus camouflages itself. Curiosity about their camouflaging techniques led to the discovery that octopus skin contains pigment that aides with color identification and that’s usually only found in the eyes This led to some testing which revealed that the skin contains chromatophores which react to exposure to specific types of light. These tests revealed that octopus skin is most responsive to blue light. If this is true, it gives a whole new meaning to the old phrase “eyes in the back of their head.”
The challenge scientists face is how they’re going to prove their hypothesis. The simplest way would be to cover the octopus’s eyes and wait to see if the skin responded to external stimuli. Sounds simple enough, but so far, the octopus used in the experiment haven’t been keen on the idea of wearing a blindfold.
They Have Smart Arms
Octopuses are smart. Really smart. A large octopus’s brain is approximately the size of a walnut, the same size as an African gray parrot, which is considerably larger than the brain of other invertebrates. Even more impressive is that scientific testing shows that the common octopuses have 130 million functioning neurons (humans have 100 billion.) The interesting thing about this is that only a small portion of these neurons are located in animal’s actual brain. Approximately 3/5 of the neurons are divided up into the animal’s eight arms. That’s right, those arms are smart. This is especially worrisome when you consider that one of the ways that eel’s attack an octopus they’ve decided to prey on is by ripping off the arms one by one (the eel devours the arm as soon as it remove it) until the octopus is armless and defenseless. That being said, ripping off the arm isn’t necessarily the safest thing the eel can do. Not only does this give the octopus an opportunity to beat a hasty retreat, but since the arms continue to not only move, but also latch onto things for several minutes following its separation, meaning that even the detached arm can do quite a bit of damage to the eel.
And, the strangeness continues. Studies indicate that the arms aren’t the only thing that’s smart. Each individual sucker is also quite clever. Not only are there thousands of neuron in every single sucker, but there are also several different nerves which provide the octopus with a great deal of information about its environment, what it’s about to eat, and any item it’s handling.
The Octopus Kingdom has a Real-Life Mutt and Jeff Couple
If you dive deep into the tropical waters you may encounter the beautiful female blanket octopus. As an adult, she’s about 2 meters long so she’s hard to miss. Her male counterpart, he’s another story. Male blanket octopus don’t grow past 2.4 centimeters in length. It’s the most extreme case of sexual size-dimorphism anyone has ever encountered. Due to the differences in their size, for most of history, biologists assumed that the animals represented two different species. The fact that females have webbing attaching their first two arms and the males don’t, made it even more difficult to grasp that the males and females represent the same species.
When it’s time to mate, the male detaches his penis (called a hectocotylus) and simply passes it on to the female. This practice is fatal to the male. The female tucks the hectocotylus into her mantle where she stores it until her 100,000 eggs are fertilized.
The male’s hectocotylus is its third right arm which contains sperm packets (officially called spermatophores.) The process is fatal for the male, who after mating becomes senescent. Aquariums report that the males not only break down physically after the mating process, but also exhibit signs of senility.
Female octopuses live just long enough to protect their eggs. Once they’ve laid their eggs, she won’t leave her den. She spends all of her time cleaning the eggs and making sure that no predators gain access to them. She doesn’t eat anything while this is happening and it’s easy to see the toll the chore takes on her body as she steadily wastes away. By the time the eggs are ready to hatch, she has shrunk to half of her original mass and lost all of her color. Shortly after the eggs hatch and the juvenile octopuses (officially called paralarvael octopus) she passes away. Researchers have discovered that is what leads to her demise. Scientists refer to the phenomenon as a type of pre-programmed genetic suicide. The glands can be removed, but in doing so, the female loses her maternal instincts.
The newly hatched octopuses drift to the sea’s surface where they float around in the plankton. Of a brood of 100,000 hatchlings, it’s estimated that only 0.003 will reach adult hood. While they float/swim around in the clouds of plankton, the baby octopuses eat anything that’s smaller than themselves, including other octopuses. During this time, their rate of growth is 5% per day.
They’re Brilliant Mimics
We’re only just starting to fully understand just how skilled octopuses are when it comes to mimicry. They have the intelligence and ability to mimic other aquatic life such as lion fish and flat fish. And, as impressive as their ability to mimic other sea life is, that skill is dwarfed by their ability to mimic other complex things, such as the size, texture, shape, and color of a rock that’s covered in algae and sea weeds. This ability to mimic just about everything allows them to both catch prey and evade predators. The really cool part is that the octopus somehow manages to learn this skill on their own. Since their mother dies almost as soon as the egg hatches, the young are forced to learn import life skills, such as mimicry, on their own.
And seemingly changing their body shape and color is just one of the tricks they have in their bag of tricks. It turns out that another thing found in octopus skin is iridophres which make the skin reflective, allowing the octopus further meld with it’s surroundings.
They Can Survive Outside of Water … Sort of
Like fish, octopus aren’t meant to live outside of water. Their respiratory systems just can’t handle life on dry land. That being said, just because they can’t stay out of water for long, they do tend to survive longer than most other sea dwelling animals. The ability to live for several minutes outside of water allows small octopus that inhabit the shallows and tidal pools to “walk” across beaches and climb rocks in while they search for food. These adventurous octopus live longer if they wait for night time or heavily overcast days before crawling across the beach. The sunnier the day, the more dangerous it is for the octopus to be out of the water.
It’s Extremely Rare to Find an Octopus with Less than Eight Arms
While there well documented instances of octopuses losing arms you shouldn’t expect to encounter an octopus with less than eight arms. That’s because the animal’s physiology is such that it can regrow any appendage it loses to an eel or in an underwater accident. The regrowth process starts the second the arm is loss and continues until the octopus has regenerated a completely new arm. What makes the process different from other animals that are able to regrow appendages is that the new arm is every bit as good as the one they loss, instead of being inferior quality.
Anderson, Roland C., Mather, Jennifer A., Wood, James B. Octopus: The Ocean’s Intelligent Vertebrae. Timber Press. 1 November 2013. Ebook. https://www.goodreads.com/book/show/7367893-octopus
Blanket Octopus. Wikipedia, Web. accessed 22 Oct 2017. <https://en.wikipedia.org/wiki/Blanket_octopus>.
Costandi, Mo. “The octopus can see with its skin” . The Guardian, 20 May 2015. Web. 22 Oct 2017. <https://www.theguardian.com/science/neurophilosophy/2015/may/20/octopus-skin-contains-light-sensors>.
Courage, Katherine Harmon. Octopus! The Most Mysterious Creature in the Sea. Penquin Group LLC, 2013. Ebook. <https://www.goodreads.com/book/show/19321988-octopus>.
How long can an octopus survive out of the water?. Biology, Stack Exchange, Web. 22 Oct 2017. <https://biology.stackexchange.com/questions/43456/how-long-can-an-octopus-survive-out-of-the-water >.
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