What does the mollusk octopus eat to grow? How long does it live? How many legs does it have? What is the difference between it and squid? (With farming tips)

The octopus, also known as the eight-armed fish, stone dweller, dead cow, stone sucker, and tide watcher, is a common mollusk in the ocean. It is a carnivorous animal and often feeds on crustaceans (shrimp, crabs, etc.). So how long does an octopus live? How many legs does it have? What is the difference between it and squid?

How long does it live?

The average lifespan of an octopus is only about 3 years. If living conditions are ideal and it is not caught, it can live up to about 4 years at most. The lifespan of deep-sea giant octopuses is different. Some scientists say that the deep-sea giant octopus can live to be a hundred years old, and its incubation time alone is as long as 4 and a half years. The largest octopus tentacle found so far is about 10 m long. Biological experts say that octopuses with tentacles more than 15 m long may exist in the deep sea.

How many legs does it have?

An octopus has 8 legs. The octopus body is short and oval, sac-like, and finless. The boundary between the head and the body is not obvious. On the head are large compound eyes and 8 retractable arms. Each arm has two rows of fleshy suckers, and the arms are connected by a membrane and vary in length. The arms have 2 rows of sessile suckers, so it is called an “eight-armed type” and does not belong to the fishes.

Differences from squid:

Family and genus differences

1. Squid: Squid is a mollusk in the animal kingdom, Mollusca, Cephalopoda, Coleoidea, Teuthida, Loliginidae, Loligo.

2. Octopus: Octopus is a mollusk in the animal kingdom, Mollusca, Cephalopoda, Octopodiformes, Octopoda, Incirrata, Octopodidae, Octopus.

Arm and tentacle differences

1. Squid: The squid body is slender and long-conical, with more than ten tentacles, two of which are longer. The front ends of the tentacles have suckers, and the suckers contain horny toothed rings. When hunting food, it uses its tentacles to entangle and swallow it. It likes to gather in groups, especially during the spring and summer mating and spawning season.

2. Octopus: The octopus body is short and oval, sac-like, and finless. The boundary between the head and the body is not obvious. On the head are large compound eyes and 8 retractable arms. Each arm has two rows of fleshy suckers. It usually crawls with its arms and sometimes swims by stretching and contracting the membrane between the arms. It can grip other objects powerfully and uses the funnel under the head to squirt water for rapid backward swimming.

Feeding habit differences

1. Squid: Squid is a fierce carnivorous animal. Its food is mostly small pelagic and midwater species such as anchovies, sardines, trevally, and krill. It also preys heavily on its own kind, and it is itself an important food for tuna, mackerel, hairtail, and seabirds.

2. Octopus: The octopus feeds on lamellibranchs and crustaceans (shrimp, crabs, etc.), and some species feed on plankton. The octopus draws water into its mantle, and after breathing, expels the water through the short funnel-like siphon. Most of the time it crawls along the seabed with its suckers, but when startled it squirts a stream of water from the siphon. The jet of water is powerful, allowing it to move quickly in the opposite direction. When in danger, it squirts an ink-like substance as a smoke screen. The substance produced by some species can paralyze the sensory organs of attackers.

Distribution differences

1. Squid: Squid is distributed in tropical and temperate seas between 40° north and south latitude. The world's main squid fishing grounds are in the northern South China Sea, the Gulf of Siam, Kyushu in Japan, the central Philippine Islands, western Western Europe, and the eastern and western waters of the United States. The fishing grounds are mostly located around islands and reefs, where the water is clear and the current slow, salinity is relatively high, the bottom is coarse and hard, the seabed has hollows, and coastal water systems meet warm current systems.

2. Octopus: Octopus is widely distributed in tropical and temperate seas around the world, and is found along the coasts of both northern and southern China. It lives underwater, and the adapted water temperature cannot be lower than 7°C. A seawater specific gravity of 1.021 is most suitable, and it will die in a low-salinity environment. The bottom material of the sea area is best as gravel zones.

Cage farming techniques:

1. Cage setup: Cage farming can be used (3.94 m × 1.82 m × 0.9 m, with mesh smaller than the individual fry, and a net cover must be added to prevent octopuses from escaping). It is mostly farmed in calm bays, and the suitable water temperature is 15-23°C. Under normal circumstances, it is mostly farmed in spring to summer (June, July) and autumn (October to December).

2. Seedling stocking: Octopus seedlings caught by traps are the most suitable, and those caught by bottom trawls can also be used. The stocking amount varies depending on water temperature and water flow. With large cages, stock 36-42 kg of seedlings per 1 cubic meter. With small cages, stock 25-30 kg of seedlings per 1 cubic meter. To prevent seedlings from killing each other, the same batch of seedlings should be stocked. It is best to put the seedlings into the cages after they are full.

3. Bait feeding: Low-priced small trash fish and shellfish can be provided. Frozen small trash fish can also be provided, but they must be fresh. When there is a lot of leftover bait, it is best to reduce it as appropriate or stop feeding for 1-2 days. Leftover bait will pollute the water quality. If feeding is stopped for more than 3 days, they will kill each other. At a water temperature of about 13°C, feeding behavior is irregular, and below 7°C the octopus does not feed.

4. Farming management: The cage farming method is suitable for large-scale farming. The survival rate of seedlings caught by traps after 2 months of farming is 70-80%, and the survival rate of seedlings caught by angling is about 50%. When seedlings are stocked in cages, the mortality rate reaches 20-30% in 15 days, and then the mortality rate gradually decreases. After 15 days of farming, divide the octopuses into large, medium, and small sizes and raise them separately in different cages. In spring and autumn, clean the cages once every 15 days, and in winter, clean them once every 30 days.