- A-Z Animals
Octopus, a cold-blooded mollusk belonging to the Cephalopoda class, grouped with cuttlefish, nautiloid, and squids, has around 300 species. These giant-sized invertebrates, with their unique appearance, have been immensely popular as sea monsters in mythology, also being a part of several literary works.
Size: Most of them have an arm span of about 14 ft. while for species like the Giant Pacific octopus, it can be as much as 32 ft.
Weight: The adults approximately weigh 33 pounds, with the giant Pacific weighing about 110 pounds on an average.
Color: They can be found in a wide range of colors because their skin has specialized cells called chromatophores containing pigments of red, yellow, brown, black, and orange pigments. Most of them possess three of these colors, while some may have two or four.
Heart: It has three hearts. One is a systematic heart assisting in blood circulation throughout its body, while the other two are branchial hearts helping to pump blood into both its gills
Head: It is large, also containing the brain and mouth.
Mouth: The mouth is situated underneath its arms, also having a sharp and hard beak.
Eyes: It has two big eyes situated on top of its head. The eye pattern is just like that of a fish, remaining enclosed within a cartilaginous membrane, joined to the cranium.
Mantle: It is a muscular structure with a hollow, bulbous shape, attached behind its head, having a majority of the crucial organs.
Gills: Octopuses have two gills contained in the muscular walls of the mantle cavity, through which they breathe. However, they do not have lungs.
Limbs: According to the recent studies, scientists have concluded that out of their eight limbs, two are legs, and the remaining six are arms. They swim and move about on the seafloor using their legs. On the other hand, their hands help them with eating and holding objects.
Teeth: They have tiny teeth arranged in multiple rows, placed within their radula, which is a spiked, muscular organ similar to a tongue.
Skin: Their skin indeed has an interesting texture, with the presence of several cells helping in color change, as mentioned above. The skin’s muscles help to change the mantle’s texture, assisting them in camouflaging in a better way.
For instance, in certain species, the skin can attain a spiky look, resembling algae. Diurnal octopuses dwelling in shallow water possess a complex skin structure than the nocturnal species inhabiting deep waters.
Nervous System: The nervous system is extremely complex, with only a portion of it confined to the brain, contained within a cartilaginous capsule. 2/3rds of its neurons are present in its arm’s nerve cords, helping them perform a host of reflex actions even when the brain provides no input at all.
They may be found in every ocean worldwide like the East Atlantic, Pacific as well as the Mediterranean Sea.
Different species of octopus adapt well to several marine habitats. For instance, the Common octopus dwells in shallow tide pools when they are juveniles. The Hawaiian Day Octopus thrives on coral reefs. The Spoon arm octopus, on the other hand, dwells in abyssal plains at a depth of approximately 1000m, while the Cirrate octopuses thrive in deep-water regions. However, no species live in freshwater areas.
Octopuses have a relatively short lifespan, with certain species living for just six months. On average most of them do not survive for more than one or two years. The Giant Pacific Octopus is said to have the longest life expectancy, living for approximately five years. Reproduction is said to limit their lifespan as the males die postmating, while the females pass away shortly after the eggs are hatched.
The diet varies from one species to the other, though they commonly eat polychaete worms, crustaceans clams, whelks, fish, prawn, crabs, scallops, and spider crabs.
There are more males than females; hence, the former may be at a tussle with each other to get hold of their prospective partner. The males often warn their competitors to stay away by flashing colors, and in case this does not work, they battle it out to win their mate.
During reproduction, the males use the hectocotylus (a specialized arm) that has a length of about 3 feet, to hold the sperms. The transfer mechanism varies from one species to the other. The male could come in contact with its mate and insert the sperm into her oviduct. He may even give the arm to the female directly so that she could store it for the future in her mantle.
The female further fertilizes the eggs by spreading the sperm over them. In species like the Giant Pacific Octopus, the male changes the texture and color of its skin during courtship.
She is highly protective of her eggs, guarding them rigorously for approximately five months against any predators, as they take that long to hatch. During this time, the mother stops eating and hardly goes out of her den. She ensures the cleanliness of her eggs by aerating them well, as most of them may not hatch if proper care is not taken. Since they lose their parents early, most octopuses get on their own from the time they hatch.
1. How many brains does an octopus have?
It has nine brains in total. The entire nervous system is controlled by a central brain, while each of its eight arms has a small brain each, helping them in functioning independently.
2. Does octopus have bones?
No, they do not have bones but a hydrostatic skeleton, giving them a flexible motion.
3. Is an octopus a mammal?
No, it is an invertebrate animal, lacking a spinal cord.
4. What is a baby octopus called?
When newly hatched, they are known as larvae, while the young ones are referred to as fry or hatchlings.
5. What is a group of octopus called?
6. Where do octopuses come from?
The class of cephalopods to which the octopus belong were said to have originated from the nautiloid, which evolved 500 million years back. However, there are different theories regarding the evolution of these creatures.
7. How fast can octopus swim?
They can swim at a speed of 25 miles/hour.
8. What eats the octopus?
Some of its predators include birds, large fish, certain species of whales, dolphins, and eels.
9. What color is the blood of an octopus?
Octopus has blue blood, mainly because of the presence of hemocyanin, a protein-rich copper, helping in the transportation of oxygen.
10. Can octopus live
out of water?
They can, but for a couple of minutes, as staying out of water for a prolonged period could cause damage to their gills.
11. What sound does an octopus make?
They hunt silently, hardly making any sound, except that of their movement through the waters as they pass by.
12. Can an octopus eat itself?
There is specific evidence of octopuses suffering from self-cannibalism where they end up eating their arms, stress being the main reason.
13. What type of an immune system does the octopus have?
Their immune system is innate. The hemocyte responds to infection through encapsulation, phagocytosis, and infiltration.
14. How many tentacles does octopus have?
They do not have tentacles, and this term refers to their limbs.
15. What is the plural of octopus?
Octopuses; the forms octopodes (used in ancient history), and octopi are considered incorrect.