Octopus and squid
The order of Octopus, like the order of closely related squid, belongs to the class of cephalopods. This is because their feet, or rather their tentacles, attach directly to their heads. They are among the oldest creatures on earth and have been swimming through the oceans for 550 million years. The best-known representative of the octopus is the common octopus with the scientific name Octopus vulgaris.
You can actually recognise Octopus or squid at a glance: They consist of a sack-shaped body, two large eyes and many long arms. And that is exactly the question: how many arms do they have – eight or ten? That depends on whether it is an octopus or a squid.
In both cases, the scientific name gives it away: Octobrachia means eight-armed. Octopus therefore have eight tentacles. The octopus order, on the other hand, is called Decabrachia, so they have ten arms – eight shorter ones and two long ones that serve as special tentacles.
These two long tentacles can be curled up and retracted, so it sometimes looks as if they too only have eight arms.
The body is very similar in squid and octopus: The elongated oval mantle encloses all the internal organs, then comes the head with the large eyes and finally the tentacles. In Octopus, the tentacles are up to one metre long and have suction cups arranged in two rows.
Depending on how big an octopus is, it has shorter or longer tentacles. And Octopus can vary in size depending on the species. While the common squid only grows up to 65 centimetres (the tentacles measure about 30 cm), there are giant squid in the deep sea that are several metres tall and have huge tentacles.
Octopus and squid have neither a shell, nor bones, nor cartilage. So they are quite soft and supple. Only inside their bodies are there remnants of a shell:
In Octopus these are two flexible rod-shaped shell remnants, in squids a white, elongated-oval structure, the so-called shoulderp.
Normally, Octopus and squid are light or dark brown in colour and the skin bears a marbled pattern. But they can change colour in a flash, showing whether they are aggressive, angry or excited.
They also change their colour and the pattern of their skin at mating time. They can also adapt perfectly to the ground and make themselves invisible to enemies.
The common octopus lives in the Mediterranean Sea, in the Atlantic Ocean from Africa to Norway and in the North Sea.
Octopus only live in seas where there is enough salt. That is why they are not found in the Baltic Sea or the Black Sea.
Octopus usually live on the seabed up to 200 metres deep and on rocky shores. They crawl along the bottom or walk with their tentacles as if on stilts. They like to hide in rock crevices.
Cuttlefish swim both just below sea level and at depths of several thousand metres on the seabed.
Breeds and species
There are about 200 different species of octopus and more than 500 species of squid in the world.
The best-known representative of the Octopus is the common octopus.
There are even very poisonous species, such as the blue-ringed octopus. It lives in the sea around Australia and Southeast Asia.
It is not known exactly how old Octopus or squid can become. Probably only about two years.
One of the best-known representatives of the cephalopods is the common octopus (Octopus vulgaris) – whose behaviour is described here:
Octopus are real loners. They like to hide in crevices and caves.
Read more about Octopus Girl
Because they can slip through the narrowest gaps with their soft bodies, they sometimes retreat into an empty drink can on the seabed.
If they cannot find a hiding place, they pile up a wall of stones around them with their tentacles.
Most of the time, Octopus sit in their caves and wait there for their prey, which they then grab in a flash from ambush with their tentacles and overpower.
Often Octopus give away their hiding places because around their cave lie the remains of their prey’s shells.
Octopus are among the most fascinating creatures of the oceans: although they belong to a very old and primitive group of animals (they are quite closely related to snails and mussels, for example), they are very intelligent.
They can also see almost as well as we can: Reportedly, Octopus kept in aquariums can remember the faces of their keepers.
Researchers have found that Octopus have a very well-developed nervous system and an excellent memory.
They can remember colours and shapes and even distinguish them from each other.
To swim, Octopus squeeze the water they breathe out of their bodies and use the force of the backwash. This also enables them to flee quickly from enemies.
But they have also developed a clever technique: When things get really dangerous, Octopus ejects an ink-like liquid. Firstly, the enemy can no longer see anything, and secondly, the ink numbs the pursuer’s sense of smell. By the time he can smell and see properly again, the octopus is long gone.
Friends and enemies
The Mediterranean moray eel, the conger eel, sharks, and some dolphin species are the octopus’ biggest enemies.
Octopus hunt all marine animals that they can overpower. They grab the prey with their tentacles, hold it with their many suckers and pull it to their mouth. If the prey has a solid shell – like mussels and crabs – it is cracked with the octopus’ powerful horned beak.
The Octopus then inject a digestive juice into the prey. This juice dissolves the prey; the pulp is then sucked up.
Octopus and squid Offspring
Octopus mate only once in their short lives – and that is the only time these solitary animals seek company.
Usually the males fight fiercely for a female. When it comes to mating, both sit far away from each other. Only the so-called mating arm of the male reaches over to the female. This arm contracts in a wave-like manner, and so the sperm capsules are released into the female’s sexual orifice. The male then dies.
Octopus mothers take good care of their brood. After laying up to 150,000 eggs in stone nests, they guard their offspring without rest. They fan the eggs with fresh breathing water, keep them clean and protect them from enemies. The female stays with her clutch for a whole month. During this time, she does not eat any food. When the young Octopus hatch, the female dies.
The little octopuses are now left to fend for themselves. They spend the first two months in the open water. Many fall victim to hungry enemies. Only when they are bigger do they look for a safe hiding place on the ground.
Octopus and squid Diet
One of the best-known representatives of the cephalopods is the common octopus (Octopus Vulgaris) – whose behavior is described here:
Octopus eat mainly crabs, mussels and shrimps. Occasionally they even hunt other Octopus or fish.
They even build up real stockpiles by collecting prey in their hiding places and eating them later.
In aquariums, they are provided with fish, shrimps, mussels and also frozen food.
So that the intelligent animals don’t get too bored in their enclosure, the food is often given to them in different containers that they have to open themselves – no problem for the clever Octopus!
Octopus and squid Keeping
Octopus are kept in many marine aquariums. There you can observe these fascinating animals very well. Many even become really tame.
In order for Octopus to feel comfortable, the water temperature in the aquarium must be below 20° C.
On no account should you forget to cover the aquarium with a heavy glass plate: Octopus is quite curious and can easily lift a light lid to explore the surroundings.