Valerie Haddix, Gina Hill, Margaret Lange, Maina Miranda, and Raina Rindani
Species have long since been evolving and will continue to evolve for years to come. Evolution has also given rise to intelligence, which can vary from species to species. Humans are considered the most intelligent, however there are many other species that possess an incredible amount of intelligence. One such species that is often forgotten about is the octopus. They possess a great amount of intelligence and many fun adaptations as well. But first, what is an octopus and what adaptations does it possess? An octopus is an organism with no bones and eight long limbs with suckers lining each one. Their lack of bones allows them to squeeze into many tight spaces with ease, which is impressive considering how large they normally are. Not only this, but they are also known for their ability to blend into their surroundings by changing their color and texture. However, some lesser known abilities that they possess is the ability to use tools, and even shell drilling. These abilities plus others will give a better picture as to the intelligence of an octopus.
Approximately 75 million years ago, ancient octopuses were drilling into their prey (Gramling 2021). There were three fossil clams found that had tiny holes drilled into them. The clams that once lived in what is now South Dakota were found with telltale oval-shaped holes. They were between 0.5 and 1 millimeter in diameter, which is thinner than a strand of spaghetti. Modern octopuses will use their sharp ribbon teeth, called a radula, on its tongue in order to drill a hole into thick shells of their prey (Gramling 2021). This is useful because oftentimes the shells are too tough for the octopus to pry them apart with its suckers. Once the hole is created, the octopus will inject venom into the hole, which paralyzes the prey and dissolves it enough to eat. The holes left by these octopuses are easily identifiable through fossil records. However, due to the soft bodies of octopuses, they tend to not fossilize well enough to identify what they looked like 75 million years ago. With the few fossils that do exist, there is little change in the basic body plan from these ancient octopuses to the modern-day ones. The finding of this little change of body plan puts the evolution of octopus drilling directly within the Mesozoic Marine Revolution (Gramling 2021). This was an escalation in the ancient arms race between ocean predators and prey. Those predators that were lurking on the seafloor became adept at crushing or boring holes into the shells of their prey.
In addition to shell drilling-techniques, octopuses have been known to use tools, which is an extremely advanced behavior for an invertebrate (Keim, 2009). The first tool usage recorded was by octopuses in Indonesia, which were observed to be using coconut shells as tools (Keim, 2009). The reason this was considered tool use as opposed to sheltering like crustaceans is because these carried these shells for future use (Keim, 2009), engaging in behaviors such as stilting, during which they use six of their arms to carry shells and two of their arms to “walk” on the bottom of the ocean floor (Waterman, et al., 2011). They also use the coconut shells in a variety of ways for hunting crab (Waterman, et al., 2011). Other tool use behaviors that have been observed are the use of rocks and shells to barricade themselves from predators and cover their dens, and play-like behavior with small rocks and with schools of fish (Thiyagarajan, 2020).
Color/Shape Changing Abilities
Octopuses are fascinating creatures with amazing abilities. One example being, octopuses can change color and even their texture. This ability is mostly used to evade predators (Two Oceans Aquarium, 2021). They can camouflage themselves by matching the color and texture of corals, rocks, and other objects nearby. To achieve the changing color effect octopuses have thousands of cells just below their skin called chromatophores (Two Oceans Aquarium, 2021). Each of these cells has a small sac filled with either red, orange, brown, yellow, or black pigment (Two Oceans Aquarium, 2021). By stretching and squeezing these sacs they can rapidly change the brightness of each color. Under the chromatophores is a specialized cell layer called iridophores. These cells are filled with thousands of tiny mirror-like structures called reflectosomes that reflect light back up through the octopus’s skin (Two Oceans Aquarium, 2021). This allows the colors to appear brighter. It is also responsible for adding shades of blue and green. The final structure involved in this process is the leucophore. This is another reflective structure that lies below the iridophores. Leucophores scatter light so on the surface it looks white but in the ocean the octopus can passively scatter light at whatever wavelength is present in its environment (Two Oceans Aquarium, 2021). This whole process takes around 200 milliseconds. No other creature on earth can camouflage as fast and effectively as an octopus. They can change their skin color, contrast, brightness, and pattern faster than a human can blink. They also can change their texture and shape drastically. This is done by contracting small regions in their skin called papillae (Two Oceans Aquarium, 2021). In papillae muscle fibers run in a spiderweb pattern (Two Oceans Aquarium, 2021). When these fibers contract they draw the soft tissue in the papillae towards the center ultimately changing their shape and texture.
Due to the high intelligence of octopuses, it is important to provide enrichment to them in captivity to keep them mentally stimulated. They are known for their ability to learn and retain information as well as their highly developed intelligence. To keep the octopuses in captivity physically and mentally active, the New England Aquarium gives their two, giant Pacific octopuses puzzle boxes (Blasi 2016). They place crab meat inside a clear box, and the octopus opens three latches to reach the treat inside. The octopuses are even given other puzzle boxes that have different shaped latches to keep the activity new and stimulated (Blasi 2016). Additionally, octopuses show a high play drive, so it can be beneficial to give them toys to play with in their enclosure. At the Seattle Aquarium, a study was conducted with three types of toy, named “ball, cow, and pliers” to see which type of toy they generally preferred and gave the best play experience (Anderson n.d.). Results showed that the octopuses preferred playing with the cow toy, presumably due to the movable rings attached to the toy, and played with it the longest (Anderson n.d.). Since the cow toy had moveable parts, there was a greater enrichment experience for the octopuses. Sometimes, the octopuses are given pill bottles to open as enrichment. Since the pill bottles have to be pressed down before opening, providing the octopus more of a challenge than other bottles. One octopus at the Seattle Aquarium opened the first pill bottle within 15 minutes (Anderson & Blunstein n.d.). However, the other times she was given the bottle, the octopus was able to open it, on average, in 2 minutes (Anderson & Blunstein n.d.). This shows their ability to take what they’ve learned from previous tasks and apply their knowledge to future enrichments. It is interesting to see how different areas of captivity enrich their octopuses, giving mental stimulation for such intelligent creatures.
Through adaptations, behaviors, and ability to learn, we have observed the extremely high level of intelligence that octopuses exhibit. Not only are octopuses extremely intelligent creatures in general, but they are especially intelligent because no other invertebrates have been known to exhibit such high level cognitive functioning. Researchers explain such high intelligence because octopuses live alone and have relatively short life-spans, meaning in order for their species to survive, they must be extremely likely to reach adulthood and reproduce successfully. Through octopus captivity and through long-term research projects, humans have cultivated meaningful and deep relationships with these creatures of high intelligence, and many scientists hope to continue in the future.
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