Octopus: Shape-Shifting Ocean Wonders
Disclosure: Some links may be affiliate links. If you buy an item via links on our site, we may earn a commission. Learn more.
From their ability to change color and shape-shift to their unparalleled problem-solving skills, the octopus is a true wonder of nature that has thrived in the depths of our oceans for millions of years.
These mysterious and enigmatic cephalopods are marvels of evolutionary engineering. With over 300 known species of these marine mollusks, each with its distinct traits and behaviors, there is a lot to discover about them.
Get ready to be amazed by the wonders of the octopus as we unravel the mysteries that make them one of nature’s most extraordinary creations.
What is an Octopus?
The word octopus comes from the Ancient Greek language with the word okt meaning eight and the word pous meaning foot. With more than 300 species in our oceans, these cephalopods are certainly abundant.
It’s thought that the octopus has been around for more than 500 million years. During the early stages of its existence, this creature would have had a shell, but scientists think that it lost this sometime during the Jurassic period, around 140 million years ago.
Octopuses can be found in all seven seas, but they have a preference for tropical and temperate waters. Due to their extensive distribution, various species of octopus have adapted to different marine habitats. Some are found in very deep, cold parts of the oceans, while others live around coral reefs. Some prefer a seagrass environment, whereas others frequent tide pools.
The octopus is an invertebrate and, as well as having eight arms, these amazing creatures have more than one brain; a mini-brain located at the end of each arm. They’re also incredibly intelligent and have even been shown to be able to solve mazes in studies in order to get to food.
Anatomy
The anatomy of the octopus is fascinating. With a complex nervous system and a cardiovascular system made up of three hearts, they’re certainly unlike any other creature on the planet.
Nervous System
Unlike other mollusks, the octopus has a rather large brain. It’s much more in proportion to its body size than other similar creatures. What’s more, its brain is shaped like a donut! The octopus body contains more than 500 million neurons and, when you compare this to the 18,000 neurons of the sea slug, it’s not hard to see why octopus are so intelligent. In fact, they have a similar number of neurons to a dog!
But these cephalopods also have a mini-brain at the end of each of their arms. Each of these arms is able to taste, touch and move independently of the rest of the body and this complex system means that the octopus is able to do things much more quickly and efficiently.
Cardiovascular System
The cardiovascular system of the octopus is just as amazing, and these animals have three hearts! But the way that their hearts work isn’t all that dissimilar to ours; it’s just that, rather than having one heart for several functions, the three hearts work together. The first heart is there to circulate blood around the body, while the other two send it via the gills as a way of getting oxygen.
And speaking of blood; did you know that an octopus has blue blood? That’s because of a protein called haemocyanin and, unlike human blood that contains iron, this protein contains copper which makes the blood a different color.
Mantle
The body of the octopus is called the mantle and this is a bulbous structure made from muscle which houses the animal’s organs. Inside, there is the main brain, the liver, kidneys, stomach and digestive organs, and even the reproductive organs.
The mantle is made from soft tissues and contains no bones which allows the creature to move through narrow or tight spaces with ease. This helps when the octopus needs to get away, but it also uses a process called jet propulsion for this. Normally, these creatures will slowly crawl around, but when they need to make a quick getaway, they’ll pump water into the mantle and then expel it through a siphon.
On the top of the mantle, the octopus has two eyes which allow it to see relatively well.
Arms
We’re all familiar with the idea that octopuses have eight arms. The underside is covered in a row or two of suction cups, each of which has up to 10,000 neurons and allows the animal to move along the ocean floor. They also use these suckers to assess their surroundings, thanks to special cells that help them to taste and smell.
In terms of holding onto things, these suckers come in very handy. The outer surface of the sucker creates a seal, while the inner part releases pressure and creates suction so these animals can stubbornly stick to a surface. The arms are also incredibly flexible.
Octo arms work pretty quickly since they don’t require signals from the brain. They work independently of the main brain, thanks to reflex loops. Even more fascinating is that when the limbs are severed, they can continue to work for around one hour.
Mouth
The mouth of the octopus is perfectly designed to catch prey since it features a beak made from keratin that’s similar to that of a parrot. This is used to break open clam shells and other hard foods as well as tear the flesh of its prey.
Since octopuses eat a lot of shellfish, they need a way to extract the animal out of the shell, and they do this with a barbed tongue known as a radula. There’s even an organ in the mouth called the salivary papilla that the octopus uses to drill into shells and release the animal inside.
Reproduction & Life Cycle
One of the most fascinating things about octopus reproduction is that they do it with their arms! In some cases, the males may end up getting strangled by the females.
This is a process that can take several hours and sees the male transferring sperm packets to the female’s mantle. Here, she can store the sperm until she is ready to spawn, and it’s possible for her to mate with several males and store all of their sperm packets at once.
Males have a special arm called a hectocotylus that has no suckers and is primarily designed to retain sperm. However, shortly after mating, the males die, but the females survive long enough to lay their eggs. Once the eggs hatch, the mother then dies as well. She seems to know this will happen as she spends those final days watching over her eggs, not eating, and starving herself to death.
From fertilization to death, octopuses go through four life stages.
Egg
Octopus eggs are incredibly small, measuring typically around 0.1 to 0.2 inches (2.5 to 5 millimeters). Some species are able to lay up to 10,000 eggs at once.
The female octopus will inhabit a den where she will lay her eggs. The clusters of eggs are called festoons and are attached to the underside of rocks within the den for incubation. The female will spend her time protecting the eggs and cleaning them with her suckers.
Larva
Once the eggs hatch after around four to eight weeks, the octopus enters its larval stage, during which it looks like an adult, only much smaller. In this stage, the larva, known as an octopod, floats among the plankton at the surface of the water, feeding on the larva of other animals like crabs and starfish.
Juvenile
During the juvenile phase, the octopus will descend to the depths of the ocean, where it undergoes some of the most rapid growth of its life. It gains as much as 5% of its body weight every day and spends most of its time feeding.
Adult
Not all octopuses will enter the adult stage of life as they have a short life expectancy of between one and three years. If they make it to adulthood, they become sexually mature, and their primary goal is to reproduce.
Defense Mechanisms
While octopuses are large creatures, they do have several predators. These include seals, large fish, and sharks to name a few. In order to stay safe, they have some interesting defense mechanisms.
Camouflage
When feeling threatened, the octopus can change its color within seconds thanks to cells under the surface of its skin called chromatophores. These cells expand and contract causing a change in the color of the skin.
There are also some species of octopus that are able to create a texture change thanks to papillae on the skin which raise and flatten, concealing the animal among rocks, corals, and other textured surfaces.
If that wasn’t enough, there are even some species, like the mimic octopus that can alter its body shape to look like other marine creatures, which predators may not be as interested in.
The camouflage abilities of the octopus are so advanced that they have even inspired human engineers when creating camo materials.
Ink
Another way that octopuses protect themselves from predators is to distract them using ink, which they release from their ink sacs along with a water jet from their siphons. It’s thought that this causes a distraction because the ink appears in a shape that confuses the predator, causing it to think there’s another octopus.
What’s more, the ink, which is made from a combination of melanin and mucus, contains irritants that affect the senses of the predator, notably their taste and smell.
The melanin in the ink is what gives it its dark color but it also contains an amino acid called tyrosinase and that’s what causes the irritation.
Diet
Where in the ocean the octopus lives largely determines its prey. Those that live in the open ocean are more likely to feed on things like prawns and fish as well as other cephalopods. However, octopus species that spend most of their time on the ocean floor can be seen eating mollusks and crustaceans.
Octopuses have a hard beak at the mouth, which they use to break open shells and tear flesh. However, before this, they need to catch their prey which they do by biting into it with its sharp beak and injecting a venom which causes paralysis.
When it’s ready to eat, the octopus uses its radula, a long tongue-like toothed structure made from muscle, to break food down and move it towards the esophagus.
Intelligence
Compared to other similar animals, octopuses are incredibly intelligent and have very complex brains. They have the ability to use tools and can even recognize people.
In 2011, scientists put an octopus to the test to see how well it could solve a maze to reach food. The maze contained portions that would require the animal to remove its arm from the water, which made its senses diminish. Despite the challenges, the octopus was able to solve the maze, which shows that, although the mini-brains in the arms usually control them, the central brain is also capable of this.
Not many animals have the ability to use tools but the octopus can. In the wild, they have been observed using things like stones as a protective shield to their dens and some will even take tentacles from the man o’ war jellyfish to use as a weapon!
In captivity, one octopus was observed getting out of its tank and going over to another tank that contained fish. It would remove the lid, take a fish and go back to its own enclosure! In another lab, scientists wired shut a clam that the octopus would usually pry open to eat in an effort to see how it solved the problem. But it wasn’t an issue for the octopus who simply switched methods to drilling in order to access its meal.
Studies have shown that octopuses can recognize human faces and may even form positive and negative bonds with them. If an octopus likes you, it’ll respond to you calling its name and come to you. However, if it doesn’t then it may squirt you with water!
This remarkable level of intelligence has amazed scientists, highlighting the striking similarity between the intelligence of these animals and our own. They’re further studying this intelligence by measuring the brainwaves of octopuses.
Exploring the Variety of Octopus Species
There are over 300 species of octopus in our oceans, and they’re all as fascinating as one another. While I can’t include all 300 in this article, let me introduce you to some of the most amazing species.
1. Common Octopus (Octopus vulgaris)
The common octopus is found all over the world, but it is most abundant in the oceans around Japan, as well as in the Mediterranean and the eastern Atlantic. These octopuses don’t dive very deep and typically stay within 490 feet (150 meters) of the surface.
These are relatively small octopuses whose bodies measure between 1 and 3 feet (0.3 and 0.9 meters); this includes their arm span. But despite their small size, they’re still extremely intelligent and have more than 500 million neurons. They’re able to recognize human faces as well as completing tasks like opening jars and solving mazes.
The common octopus feeds on a diet of crustaceans and bivalves. While females can lay up to 500,000 eggs, most juveniles do not make it to adulthood. Those that do have a life expectancy of just one and a half years.
2. Giant Pacific Octopus (Enteroctopus dofleini)
As its name suggests, the giant Pacific octopus is found in the Pacific Ocean. It’s found all over these waters as far north as Alaska and it usually frequents shallow tide pools. In the ocean, it doesn’t swim very deep, rarely going more than 360 feet (110 meters) below the surface.
They live in dens among the rocks and feed on a diet of lobster, small fish, clams, and crustaceans. These are solitary creatures that can spend weeks at a time alone in their dens. They have a longer lifespan than many species, up to five years.
Each arm has more than 280 suckers with chemical receptors that allow the animal to examine its surroundings. Amazingly, these octopuses have excellent vision and have been shown to learn through observation!
3. Dumbo Octopus (Grimpoteuthis spp.)
There are 17 species of dumbo octopuses that belong to a family called umbrella octopuses owing to the umbrella shape at the base of the mantle, which enables them to float.
Out of all the octopus species, the dumbo octopus lives at the deepest depths of the ocean, sometimes as far down as 13,123 (4000 meters). Down here, they enjoy feeding on worms, isopods, and creatures that inhabit the areas around the thermal vents.
Dumbo octopuses can be found in many locations around the world including off the coasts of New Zealand, Australia, the Philippines, and both coasts of North America. It’s difficult to determine the conservation status of these creatures as they live at such great depths, which means it’s a real treat to spot one.
Unlike other octopus species, the dumbo does not have ink sacs, so is unable to produce ink. However, it can still expel water through its siphon to give it a speed boost.
4. Mimic Octopus (Thaumoctopus mimicus)
The mimic octopus is a relatively newly discovered species having first been spotted in the late 90s off the coast of Sulawesi. It’s found all over the Indo-Pacific region but most commonly spotted around the coasts of Indonesia.
What’s special about this octopus is its ability to mimic other animals, such as the sea snake, the lionfish, and the jellyfish to name a few. However, it most commonly takes on the appearance of the flatfish, and it uses this mimicry to allow it to approach prey without suspicion. What’s more, when it mimics poisonous fish, it’s less likely to become a victim of predation.
Mimic octopuses are not large and usually grow to around 2 feet (0.6 meters). While they are able to mimic other animals, they typically have a beige to brown coloration. Two horns above the eyes are another identifying feature.
5. Caribbean Reef Octopus (Octopus briareus)
The Caribbean reef octopus is found in warm tropical waters where it inhabits rocky sea beds and, as its name suggests, coral reefs. However, it also enjoys a seagrass habitat. These octopuses don’t swim very deep and generally stay in shallow waters no more than 66 feet (20 meters).
One of the most interesting looking species, the Caribbean reef octopus, has bright blue or green coloration with brown to red markings all over the body. These aren’t a large species by comparison and typically grow to around 23 inches (60 cm), although the mantle is quite chunky.
The appearance of this species can change, however, owing to its ability to camouflage using both color and texture alterations. They feed on a diet of fish and crustaceans but are preyed upon by stingrays and sharks.
6. California Two-Spot Octopus (Octopus bimaculoides)
Living at depths of just 49 feet (15 meters), the California two spot octopus can usually be found around rocky reefs where it hunts for shrimp and amphipods. These octopuses do not have a long lifespan and usually live for between one and two years.
Found along the coasts of California, the two-spot octopus has a range that stretches from Baja in the south all the way up to northern California. Interestingly, the species does not have a specific breeding season and can breed at any time of the year.
A small species, they typically grow to around 2 feet (0.6 meters) and weigh between 4 and 9 lbs (2 and 4 kg). These octopuses are characterized by their unique markings. They have a light brown coloration with two marks below the eyes that set them apart from other species and give them their name.
7. Coconut Octopus (Amphioctopus marginatus)
The coconut octopus is found in the western Pacific Ocean, particularly around the Philippines and Indonesia.
The species takes its name from the fact that it collects coconuts which it uses as a form of shelter. Not only this, but it has been known to use other tools, such as shells which it also uses to conceal itself. However, the species is also known for burying itself under the sandy seabed, with only the eyes protruding.
The coconut octopus is typically found in bays and lagoons where there are sandy bottoms, and it will feed on crustaceans and clams. These are small octopuses that usually grow to around 6 inches (15 cm) and have dark-colored arms with white suckers.
8. Wunderpus Octopus (Wunderpus photogenicus)
The wunderpus takes its name from the German word wunder which means marvel or wonder. It’s a pretty adept name for such a striking creature with its intricate patterns and long delicate arms. The species is brown in color with white markings all over the body. It’s a small type of octopus that grows to around 9 inches (23 cm) in length.
Found in the Indo-west Pacific region, this species is known for its ability to mimic other animals, including changing its pattern and color when it feels threatened. This is thanks to the chromatophores within the skin that enable the creature to camouflage.
The wunderpus is a burrowing species that can spend up to three weeks in the same burrow before moving on. It prefers areas with a sandy bottom which facilitates easy burrowing. It tends to frequent shallow waters no deeper than 66 feet (20 meters).
9. Blue-Ringed Octopus (Hapalochlaena spp.)
There are around 10 species of blue-ringed octopus, and they are known for their toxicity. The venom of this species contains a concoction of neurotoxins that can cause symptoms ranging from nausea to respiratory and heart failure. The main neurotoxin, tetrodotoxin, is the same that is found in the pufferfish. These octopuses are very small, measuring just 1.6 to 2.4 inches (4 to 6 cm), but a single specimen can produce enough toxins to kill up to 26 humans in a matter of minutes.
They’re found around the seas of Australia, Vanuatu, and as far north as the Sea of Japan. They spend a lot of time hiding in crevices and hanging out around coral reefs, camouflaging themselves from predators. Another interesting trait is their ability to flash their blue rings, and this is because of the chromatophores beneath the surface of their skin. They use this ability when they feel threatened as a warning to predators that they are toxic.
10. Galapagos Octopus (Octopus oculifer)
The Galapagos octopus is a species found in shallow waters no deeper than 164 feet (50 meters). As its name suggests, it’s found around the coast of the Galapagos Islands and is thought to have inhabited these waters for the last 164 million years.
These octopuses are commonly found on coral reefs and are sometimes called the Galapagos reef octopus because of this. They grow to around 16 inches (41 cm) in length, and it has the ability to camouflage itself among the rocky reef to protect itself from predators.
During breeding season, the males will perform several displays in order to attract a mate and copulation is similar to other octopus species with the male using his specially adapted arm to pass on his sperm.
11. Common Blanket Octopus (Tremoctopus violaceus)
The common blanket octopus is an interesting species in that the males and females are completely different. The females can grow up to 6.6 feet (2 meters) in length, while the males don’t get much bigger than 1 inch (2.5 cm). In order to mate, the male must cut off his arm containing his sperm and give it to the female, who then stores it in her mantle until it is ready to be used.
Another fascinating fact about these octopuses is that there have been individuals seen carrying the tentacles of the man o’ war, which they use as a weapon. They may also use these as a way of catching prey.
Common blanket octopuses are found in tropical and subtropical oceans around the world and have a relatively long lifespan of up to 5 years for the females. However, males only live to around one or two years, with the reproductive process often killing them.
12. Day Octopus (Octopus cyanea)
The day octopus is most commonly found in the Pacific and Indian Oceans however, there have been some spotted around the Mediterranean Sea and along the coasts of southeast Africa. This is a large species that can grow up to 31 inches (80 cm), including the arms.
One of the most interesting things about this species is its super ability to change its appearance, which it does as it moves along the sea bed. In one case, an individual was seen to alter its color more than 1000 times in a seven hour period.
Day octopuses live around coral reefs and don’t usually go much deeper than 328 feet (100 meters) beneath the surface. They take their name from the fact that they hunt during the daytime, which is unusual as most octopuses hunt at night.
13. East Pacific Red Octopus (Octopus rubescens)
The east Pacific red octopus is found along the Pacific coastlines of North America from as far north as Alaska and as far south as Baja. They live at depths of up to 984 feet (300 meters) around rocky areas and kelp forests.
Not much is known about the diet of this species in the wild, but captive species have been fed on bivalves, crabs, and barnacles. Interestingly, these octopuses will pounce on their prey while displaying an impressive array of color changes.
In studies, the east Pacific red octopus, which has a reddish-to-brown coloration, was the first to ever be recorded as having individual personalities. They are sometimes confused with other species, but their eyelash-like papillae are a distinguishing feature.
14. Atlantic Pygmy Octopus (Octopus joubini)
The Atlantic pygmy octopus is found in the tropical regions of the western Atlantic and prefers a coral reef habitat with plenty of places to hide, like crevices and cracks within the rocks. They will also use empty clam shells for shelter and often feed on crabs or snails where the former is not available.
Atlantic pygmy octopuses have one of the shortest lifespans of all octopus species, living only between four and eight months. However, during this time, they have rather rapid growth despite only getting to around 6 inches (15 cm) in length.
Like many octopus species, the Atlantic pygmy has chromatophores that allow it to change color. However, the range of colors they can turn is not as vast and are mainly different shades of red and brown.
15. Southern Sand Octopus (Octopus kaurna)
The southern sand octopus is native to the waters around Tasmania and the Great Australian Bight, where it grows to around 20 inches (50 cm) in length, including the arms.
This species takes its name from its habit of burrowing in the sand and they do this so often that they’re not frequently spotted by humans. Because of this, there’s still a lot to learn about the southern sand octopus, and we’re unsure of its lifespan or what predators it has. However, we do know that it feeds on a diet of mainly crustaceans.
Southern sand octopuses have thin arms and small suckers as well as a narrow, long mantle which makes it relatively easy to identify. The arms can be more than seven times longer than the mantle and, unlike other species, may vary in length.
16. Atlantic Longarm Octopus (Macrotritopus defilippi)
The Atlantic long-arm octopus is another species that is able to mimic different creatures and it does this in order to help it with hunting. It’ll often take on the form of a flatfish, or flounder, swimming close to the sandy sea floor which it inhabits. When it does this, it may even alter the direction in which it swims to be more convincing.
This species is found in the Atlantic Ocean and, despite its name, is also common in the Indian Ocean and the Caribbean Sea. They are not large octopuses and typically grow to around 3.5 inches (9 cm).
They prefer shallow waters where they will survive for around one year, usually dying shortly after mating. The main part of its diet is a variety of crustaceans, worms, and bivalves.
17. Pale Octopus (Octopus pallidus)
The pale octopus can grow up to 21 inches (54 cm) and is a robust species found only around the waters of Australia. They live in shallower water not usually being found any more than 1,640 – 1,968 feet (500 – 600 meters) below the surface, and prefer muddy or sandy sea beds.
It’s here that they will hunt for their prey, which is typically bivalves. Normally, the pale octopus will hunt at night and can often be seen to be hiding among rubble before ambushing its prey. It is also able to camouflage itself and has very strong arms to pull apart prey or drill into its shell.
The pale octopus is unique in that, from the moment it hatches, it will crawl away from the rock where its egg was laid and begin foraging for food.
18. Seven-Arm Octopus (Haliphron atlanticus)
Most octopuses have eight arms but there is one species that stands out from the crowd because it has just seven arms…well, almost. It takes its name from the fact that the male hides its mating arm in a sac below its right eye so it appears as though it only has seven arms. The only time it will reveal this arm is when it is mating.
This is one of the largest octopus species that can grow up to 3 meters (10 feet) in length and it has a large gelatinous body. Their diet is also made up of gelatinous foods such as the medusa of the egg-yolk jellyfish.
The species is found primarily in the Atlantic Ocean, and it will live as far down as 2,952 feet (900 meters). Because of this, the seven-arm octopus is one of the lesser studied species, although sometimes they are washed up on shore.
19. Star-Sucker Pygmy Octopus (Octopus Wolfi)
We’ve just met the biggest octopus in the world, so it’s only fitting that we now get better acquainted with the smallest. The star-sucker pygmy is found in the western Pacific and doesn’t grow any larger than 1 inch (2.5 cm). They weigh just 0.04 oz (1 gram) and live at depths of up to 328 feet (100 meters).
When they are young, they feed on the smallest type of plankton in the ocean called nanoplankton. As adults they feed on slightly larger plankton, but they only have a short lifespan of up to six months owing to their small size.
One of the most unique things about this species is that they are able to produce multiple festoons of eggs and do not die after mating.
20. Flapjack Octopus (Opisthoteuthis californiana)
The flapjack octopus is a mid-sized species that grows to around 8 inches (20 cm). One of their most distinguishing features is their umbrella-shaped arms which are connected, allowing them to float. Their bodies can also spread out like a parachute owing to their gelatinous nature, and this makes it easier to move through water where the light is low.
Flapjack octopuses are not often spotted, so there is still a lot to learn about them. It is known that they may live at depths between and 407 and 2,700 feet (124 and 823 meters), but some have been spotted as deep as 4,921 feet (1,500 meters). They are found in the northeastern Pacific Ocean.
Interestingly, the males do not have the hectocotylus seen in other species but instead, use a series of enlarged suckers for mating. However, mating in the wild has never been observed.
21. Atlantic White-Spotted Octopus (Callistoctopus macropus)
Growing up to 59 inches (150 cm) in length, the Atlantic white-spotted octopus is found in the warmer areas of the Atlantic as well as the Caribbean Sea, where it can often be found among the coral reefs. It lives in areas with both sandy and rubble sea floors. Usually, this species lives at depths of around 66 feet (20 meters), but in some cases, they have been spotted as far down as 328 feet (100 meters).
Easy to distinguish from other species, this octopus has a deep red coloration with white markings all over its body. They have an average lifespan of one to two years which is typical of most species.
Hunting only at night, the Atlantic white-spotted octopus uses its long arms to feel around the rocks for its prey which are mainly small fish and invertebrates.
How are Octopus Dealing with Warming Seas?
Climate change is causing the world’s oceans to get warmer, and many octopus species are struggling with this. The common octopus is a prime example of this, and it’s been shown that populations decrease when the temperature of the water changes. Because of climate change, there has been such a dramatic decrease in the number of common octopuses that there is concern it may eventually become an endangered species.
On the contrary, there are some species that appear to be thriving in the warmer temperature, according to studies in the seas between New England and Japan. It appears that their numbers have been rising because of the diversity of how they reproduce.
Some octopus species are being forced to migrate as a result of climate change. Other factors, such as pollutants, are forcing them to relocate as has been demonstrated in Spain. Where they were once abundant in the waters around the Costa Brava, they’re now only found in water that has a depth of more than 295 feet (90 meters), researchers have discovered.
One of the effects of warming oceans is the amount of oxygen in the water. Octopuses and other animals rely on a perfect balance, and even the smallest shift in the oxygen levels could cause these creatures to lose their vision.
