One of the largest known octopus species on earth is the Seven-Arm Octopus. The only other known octopus species to challenge the size of the Seven-Arm Octopus is the Giant Pacific Octopus. Let us learn 20 interesting Seven-Arm Octopus facts and find out why it has been so named, what its characteristics are etc.

Interesting Seven-Arm Octopus Facts: 1-5

1. The scientific name of the Seven-Arm Octopus is Haliphron atlanticus and it can reach to a total length of 3.5 meters or 11 feet and sometimes up to 13 feet. This octopus can weigh up to 75 kilograms or 165 pounds.

2. The name of the species is derived from the fact that one of the arms of the animal is specially modified. This arm is placed just below the right eye in form of a coiled sac.

3. This specially modified arm is used for fertilization of egg.

seven-arm octopus facts
Lateral View Showing the Hidden Arm of a Young Male | By A.E Verrill (Addison Emery), 1839-1926; – The cephalopods of the northeastern coast of America url, Public Domain, Link

4. Thus, despite its name, the octopus actually has 8 arms. Even interesting is the fact that this weird arm modification is found only in males. The eighth arm in the males is a special modification used only in reproduction and it remains coiled in a sac underneath the right eye.

seven-arm octopus facts
Oral View of the Seven-Arm Octopus | Public Domain, Link

The arm is easily overlooked because of its thick gelatinous tissue. As a result of it, species has an appearance of seven arms.

seven-arm octopus facts
Ventral View of a Young Female | Public Domain, Link

5. Unlike many species of animals where males are usually larger than females, the Haliphron atlanticus has no such size difference. Males and females are all of the same size.

Interesting Seven-Arm Octopus Facts: 6-10

6. This octopus species was accidentally discovered in 2002 near New Zealand.

7. Just like other octopus species, the Seven-Arm Octopus is pretty intelligent and is capable of adapting to different environments.

8. Its highly gelatinous body is extremely flexible, allowing it to hide in crevices and cracks.

9. The Haliphron atlanticus also uses color camouflage to protect itself from predators or for sneaking up close to its prey.

10. Unlike other octopus species, the Seven-Arm Octopus is not really picky about food. It will happily feed on any prey, making it an opportunistic feeder.

Interesting Seven-Arm Octopus Facts: 11-15

11. This octopus is known for possessing a strong beak, allowing it to crush the shells of its preys. If it fails to crush the shells, it will drill through the shell and paralyze its victim using a venomous saliva and then suck out the food!

12. The Seven-Arm Octopus is a voracious eater and will eat large amounts of food at a time.

13. Its favorite hunting time is night. There are two factors for this. First it has very powerful vision that allows it to clearly see through water and second, at night it is capable of sneaking up close enough to its unsuspecting prey using camouflage.

14. During the mating season, one male can mate with multiple females. Soon after the mating season is over, the males die because their body is designed to shut down after they produce and deposit sperm in female body cavities.

seven-arm octopus facts
Eggs and Embryo of Seven-Arm Octopus | By Richard E. Young – This image is uploaded as image number 50738 at Tree of Life Web Project ( tag does not indicate the copyright status of the attached work. A normal copyright tag is still required. See Commons:Licensing for more information., CC BY 3.0, Link

15. The females on the other hand carry the sperm for around 4 weeks until the eggs are ready to be fertilized.

Interesting Seven-Arm Octopus Facts: 16-20

16. Once the eggs are ready, females will usually find a coral reef or a suitable hiding place to lay the eggs and fertilize them with sperm.

17. During this entire time (from bearing eggs to laying them and taking care of them), the females do not eat and hence, gradually approach their death.

18. Females don’t usually live to see their offspring or even protect them from predators. This vastly increases the mortality rate.

19. Once the females lay their eggs, they keep the eggs clean by creating bubbles and blowing water on the eggs.

20. The Seven-Arm Octopus usually spends time close to the ocean floor and its usual habitat is near the slopes. However, the breed can also be found in open ocean and hundreds of miles away from the slope.

Sources: 1, 2, 3

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