Octopuses belong to the Cephalopod family together with squids and cuttlefish. They are considered to be the most intelligent of all the invertebrates, and tend to be short-lived creatures – some live for as few as six months, others may live up to five years. Most octopuses live to around three years old.
Octopuses are known for their distinctive eight arms – which are often called tentacles by mistake. Most species have suction cups on their arms, and these arms seem to have their own neurological systems, like individual brains. This means that an octopus can complete different tasks at once – for example, exploring a cave with one arm while using another to crack open a shellfish. The suction cups also have sensors on them that allow them to taste their food. Researchers believe that octopuses are very particular about which food tastes good to them, and which does not.
Octopuses have three hearts and blue blood – caused by a copper-based protein called hemocyanin. Their three hearts serve different functions – one pumps blood through the organs and the other two pump blood through the gills. When an octopus swims, the heart that delivers blood to the organs stops beating, which quickly exhausts the octopus. This may be one reason why they seem to prefer crawling to swimming.
They can travel in many different ways – by undulating in water, skimming across the seabed, jet propulsion and even walking on their arms. Octopuses spray ink when they feel threatened, in order to confuse predators and provide themselves with a temporary shield from which to escape behind.
They need saltwater to survive, so they only live wild in the ocean. They usually like to build dens amongst coral reefs and find small crevices or rocks to hide under or in.
Like all invertebrates, octopuses have no bones; the only hard bit of their body is a beak which they use to break open molluscs and shells as well as occasionally larger prey.
It used to be thought that only the blue-ringed octopus were venomous, but researchers have discovered in the last few years that all species are venomous to some degree, like their close cousins the cuttlefish. Many octopuses use their venom to force prey such as clams to open their shells to more easily feed on them.
Octopuses only mate once in their lifetimes, and this is a dangerous business for both genders. The males die a few months after mating, or in some cases are killed and eaten by the female after mating. Researchers have observed day octopuses mating on a reef in Indonesia; after mating, the female lunged at the male and strangled him, afterwards carrying him into her den to eat him.
When a male wants to mate with a female, he will approach her slowly and will signal his intention to her. He will wait to see if she will accept his advances, and if so, will extend one of his arms, which is modified for the purpose of mating. Then he will insert the arm inside the female and pass her his ‘spermatophores’ that she will use to fertilize her eggs.
Once mating is complete and the female is ready to lay her eggs, she will choose somewhere suitable and attach them to a hard substrate inside her birthing lair. She won’t leave her lair for six months, all the while protecting, cleaning and caring for her eggs, which can number up to several thousand. By the time the eggs hatch, she is starved and exhausted, and dies soon after.
Because of this, the young are left to fend for themselves and aren’t taught any life skills by a surviving parent. Hence, each new octopus learns everything they know from scratch – a fact which researchers believe has prevented them from becoming the ‘kings’ of the oceans, a title which their incredible intelligence and adaptability suggests would otherwise lie within their reach.
Octopuses have enormous brains for invertebrates, but not that large when compared to vertebrates. Despite this, they have distinct personalities, showing tendencies to be either more avoidant or more assertive. They can recognize and even show preferences for individual people – an intriguing ability, because usually only social creatures can do this, whereas octopuses tend to be solitary creatures who are highly aggressive with one another.
They are also adept at manipulating their environment, and can even use tools. In one case, at Santa Monica Pier Aquarium in California, staff discovered that a puddle on the floor next to a tank with an octopus in it was a result of the octopus disassembling a water-recycling valve.
Another story about a clever octopus in captivity is that of ‘Inky,’ an octopus who lived in the National Aquarium in Napier, New Zealand. One night his enclosure lid was left slightly ajar. The next morning, his keepers discovered that Inky had vanished – he’d managed to squeeze his way out of his enclosure and crawl across the floor, sliding through a 15cm (6in) wide drain pipe that led back to the sea: a real life Finding Nemo moment!
Octopuses in captivity have figured out how to twist off jar lids and solve simple puzzles. One theory about their intelligence is that ‘they got smart because they got soft’ – they have had to use their brains to survive because they have no hard outer shell or other protective features with which to fend off predators.
So, are octopuses like humans in regard to intelligence? Our last common ancestor, thought to have resembled a flattened worm, existed over 600 million years ago. However, an incredible commonality exists between humans and octopuses – they have developed high-resolution camera-like eyes, just as we have. This is an incredible coincidence of evolution, because it seems that this particular adaptation was arrived at twice, totally independently.
Octopuses seem to have both short-term and long-term memories, just as we humans do. They also appear to experience similar sleep states. While it’s clear that octopuses are highly intelligent creatures, it’s hard to say how closely they compare to human intelligence. Because they developed over many millions of years along a completely different line from mammals, their kind of intelligence is very different to ours – yet another reason why they seem like aliens to us!
The day, or reef octopus as it’s interchangeably called (not to be confused with the Caribbean reef octopus) is a large species that can grow up to 91cm (3 ft) long. They only live for a year and breed only once. They are typically brown in color, but can rapidly change color and skin texture into a variety of patterns to help them blend into the ocean substrate when they feel threatened.
They have dark oval false eyespots that are only sometimes visible and will depend on the patterns displayed by each individual. They feed during daylight hours, which is one reason they need to camouflage themselves so well. Their brain sends impulses to their muscles which cause them to change almost instantly to fit in with their surroundings as they move over different terrains – like sand, coral, rubble, algae and rocks.
The day octopus usually forages for crabs, fish and other small marine life and will often take prey back to its den to eat at its leisure. It uses venom from salivary glands to immobilize its prey. It can drill holes into shells using its radula and inject venom that separates the flesh from the shell. Discarded shells outside of its den form a pile known as ‘garden’.
They’re quite common in Indonesia’s warm waters and can be spotted on dives in day light. The best way to spot one is to keep an eye out for irregular movements or shapes in crevices. Once spotted, they may retreat or try to change color to further camouflage themselves.
Of all the octopodes in Indonesia and the world, the mimic octopus is probably the strangest and most fascinating. It’s a master of the quick change, altering both its shape, color and even its behavior to impersonate a range of other sea creatures.
Because most octopus are vulnerable to larger predators, they usually hide or use a cloud of ink to escape when they come across one; however, the mimic octopus stays safe by imitating other creatures, such as a lionfish with poison spikes or a sea snake, one of the most poisonous creatures on earth. It has also been seen mimicking stingrays, jellyfish, eels, starfish and flounders. The changes are almost instantaneous and are a true wonder to behold!
Mimic octopuses eat worms, crabs and small species of fish. But there is a darker side to their dietary habits – in common with many other species of octopus, they sometimes practice cannibalism. Researchers have noticed that mimic octopuses will eat others of the same species, and not always because food resources are scarce, or as a mating ritual. Experts think they practice cannibalism to maintain control over their territory.
The Wunderpus octopus is often mistaken for a mimic because they are similar in coloring and behavior. However, there are plenty of differences that are worth remembering. Mimics have a white edge along the arms and the wunderpus do not; the stripes on wunderpus are clearly defined, but far less so on mimics, who also tend to be larger and more well-muscled; and whereas mimics’ stripes can almost completely disappear, a wunderpus’ stripes are always very clear, even when it changes color. They also hunt and eat their prey differently – mimics tend to take prey back to their den while wunderpus tend to eat ‘on the go.’
See the differences in the gallery below. You should be able to tell the differences and be certain of what you see on your next dive.
These little octopuses only measure between 12-20 cm (5-8 in). However, don’t be deceived by their tiny size – these beautiful but deadly creatures each pack enough venom to kill 100 humans.
In their natural state, the blue-ringed octopus is actually a deep brown to gold color. It’s only when they feel threatened and become aggressive do they flash their trademark blue rings, which shine as a warning to potential predators. As with other species, they mate only once and the female lays just one clutch of eggs in her lifetime, caring for them until she has exhausted herself.
Blue-ringed octopuses carry a powerful muscular-neurotoxin called Tetrodotoxin, the same one found in Pufferfish. This toxin paralyses all muscles, including the heart to cause almost certain death. Blue-ringed octopus stings may be treated if immediate action is taken by qualified medical professionals.
The charming and intelligent coconut octopuses are so-named because of their clever use of coconut shells – for tools, hunting camouflage, and protection against predators. They collect and carry the shells around at all times for these purposes.
To hunt, they camouflage themselves behind the shells to wait for passing prey. When prey comes near, they ambush it, use their powerful arm suckers to restrain it, and inject their venom into the prey’s body. The venom serves two purposes: it paralyzes the prey and softens its tissue so the octopuses can easily suck it out of hard shells.
Coconut octopuses have been observed using two of their arms to walk quickly along the seabed as they carry their shells with their other arms. It’s incredible to see them suddenly stop and snap the shells together, drawing them around their bodies, when they feel threatened. These octopuses can be aggressive, and will lash out if humans or other creatures come too close. However, these octopuses aren’t a danger to humans.
Around 15 cm (6 in) long, they have brown-colored bodies and vein-like lines with a yellow siphon. Their white and blue suckers make them very pretty to look at, and combined with their clever habits with shells, they are a delightful sight for any diver.
Starry Night octopuses are rare nocturnal members of the cephalopod family, and are found during night dives amongst coral rubble, sandy bottoms, or patches of rocky coral reefs. Reddish brown in color, when they feel threatened they display white star-like spots all over its body, hence the name.
Their bodies are around 13 cm (5 in) in length, but its arms can reach up to 80 cm (31 in). It’s extremely fast moving and quite shy, so patience, luck and the willingness to dive at night is required to see one.
Another incredible creature to see while night diving is the bobtail squid. Although it isn’t an octopus, it belongs to the cephalopod family, and we love seeing them, so thought we would included in this post. Bobtail squids are tiny creatures – only 5 cm (2 in). They only live between 3-12 months long and has eight long arms and two retractable tentacles. Its diet includes small fish and shrimp.
So, why seek out this tiny cephalopod? Because of its ‘invisibility cloak’ – it has the amazing ability to host bioluminescent bacteria inside its body in a symbiotic relationship, which allows the bobtail to mimic moonlight and eliminate its shadow, thereby camouflaging it against predators.
Because it glows, it’s a wonderful night dive sighting. During the daytime, the bobtail squid has to hide itself to avoid detection. It does so by burying itself with sand and small stones from the seabed, which it flicks over itself using its sticky skin surface.
The species described above can be found in several areas within Indonesia. Raja Ampat and Komodo host a variety of different octopuses, most commonly the day or reef octopuses. Starry night octopuses and bobtail squids can be seen during night dives around Komodo.
For a better chance at seeing the mimic, wunderpus, blue-ringed and coconut octopuses, head to Lembeh Strait, the ‘muck diving capital of the world’. Muck-dives involve slowly exploring dark, sandy volcanic seabeds that at first appear to be quite desolate. In actual fact, a huge range of amazing marine life exists here. The patient explorer will be rewarded with an outstanding experience of rare species sightings.
Here are some guidelines to follow when you encounter the amazing octopodes.
Firstly, keep a safe distance and let them come to you if they wish. Don’t make sudden movements or attempt to make them react to you for photos.
Don’t harass them or try to force your presence. A dive instructor in Vietnam once had an octopus remove his regulator after he pulled on its arm; the octopus became aggressive when the instructor kept hold of it after it had already released its ink.
Almost all of the octopuses in Indonesia are harmless; however, be wary around the blue-ringed octopus and always listen to advice from instructors. It is not aggressive and will only attack if it feels threatened. Absolutely do not approach when its blue rings are lit, as this signals aggression. Carefully and slowly remove yourself from its area.
Above all, as with any sea creature, treat them with respect and gentleness, and you will be rewarded with an incredible experience getting to see these quirky creatures in their natural habitats.
For more information about diving with octopodes or to discuss planning your dream charter in Indonesia, please contact us at: firstname.lastname@example.org or +62 811 88 22 82 by phone or Whatsapp. We look forward to hearing from you.
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