Key Information
This species is my personal favourite.
Size: 2cm (males) to 200cm (females)
Lifespan: 1 to 2 years (males), 3 to 5 years (females)
Habitat: Pacific, Indo-Pacific and Atlantic oceans
Blanket octopuses have a huge size and appearance discrepancy between male and females. This is called sexual dimorphism. The blanket-like and visually stunning characteristic is only found in females and designed to intimidate with the large size silhouette it creates. Some types also have eye spots on these blankets to unnerve the threat. Blanket octopuses are always in the open ocean, never resting on the sea floor. This means they require this intimidation tactic to survive. If it doesn’t work, she can shed her blanket in hope that the attacker will become tangled, or at least temporarily block vision so she can make a quick escape.
Thieves!
Males and young females have been known to steal the tentacles of Portuguese Man O’ War ‘jellyfish’ to use for their own self defence. They hold the tentacles with the suckers on their arms and ward away any potential predators that threaten them in the open ocean. The blanket octopuses themselves have developed an immunity to the ‘jellyfish's’ sting.
Mating
You might’ve heard that octopuses can shed their arms in what's known as autonomy... well, the male blanket octopus takes autonomy to another level: the male's sex arm, or hectocotylus, detaches from him and reattaches to the female's mantle cavity. She stores enough of them to fertilise all of her eggs – this can be in excess of 100,000.
Whilst it is not uncommon for any species of male octopus to do this, it is the only way of mating for the blanket octopus. This unfortunately kills the male octopus, so, he essentially dies for sex.
When the eggs have been fertilised, the female can create a form of attachment using calcium carbonate to ensure she can hold all of her eggs securely.
Questions to be answered
What advantage does the female octopus have in being so colourful? Is it to attract a mate, or is there another reason?
Most octopuses have survived by camouflage and hiding. How did this species evolve to be so brave? Why are they pelagic?
What advantage does sexual dimorphism hold? How does this outweigh the disadvantages?
References
https://octonation.com/fun-facts-about-the-female-blanket-octopus/
Fun Facts about the Female Blanket Octopus
OctoNation
(Year Unknown)
The Blanket Octopus Looks Like a Rainbow Ghost Alien
Australian Geographic
2019
Date Published: 14th July 2023
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