The blanket octopus (Tremoctopus) is a unique cephalopod found in tropical and subtropical waters worldwide, spending its entire life in the open ocean. These animals are notable for having one of the most extreme examples of sexual size disparity in the animal kingdom. The species is named for the expansive, fleshy membrane, or “blanket,” that connects the dorsal and dorsolateral arms of the large female.
Defining the Blanket Octopus Diet
The diet of the large female blanket octopus is primarily carnivorous and consists of prey found within the water column of the epipelagic zone. The female is an opportunistic feeder. This generalist approach means her meals often include small bony fish, crustaceans, and various other invertebrates that inhabit the same warm waters. The successful feeding of the female allows her to grow to a substantial size, directly supporting her massive reproductive needs.
Specialized Hunting and Predation Techniques
The female blanket octopus employs a unique and aggressive hunting strategy that utilizes a formidable external weapon. She tears off the stinging tentacles of the highly venomous Portuguese Man O’ War (Physalia physalis), which is not a true jellyfish but a siphonophore. The octopus is immune to the potent venom contained within the man-of-war’s nematocysts, allowing her to handle the detached stinging cells without harm. This stolen armament can be used like a whip, delivering paralyzing venom to fish and other organisms that would otherwise be difficult to subdue.
The webbed “blanket” for which the species is named is also sometimes theorized to play a role in hunting, though its primary function is defense. When threatened, the female unfurls this large net-like membrane to instantly inflate her apparent size, intimidating potential predators like larger fish and whales.
The Influence of Extreme Sexual Dimorphism on Feeding
The blanket octopus exhibits the most extreme sexual size dimorphism known in any non-microscopic animal, which fundamentally dictates the feeding ecology of each sex. A mature female can reach a length of up to two meters, while the adult male rarely exceeds 2.4 centimeters. This astonishing difference results in a weight ratio that can be as high as 40,000 to one, creating two distinct creatures within the same species. The massive female requires a robust, high-energy diet of fish and crustaceans to fuel her growth and the production of up to 300,000 eggs. In stark contrast, the diminutive male’s diet is highly constrained by his size, which limits his predatory capacity entirely. Males are generally thought to consume only the smallest planktonic organisms or potentially very little food at all once they reach maturity. The male’s small body size and short lifespan are dedicated almost entirely to reproduction. The male’s inability to hunt larger prey means his ecological niche is vastly different from the female’s, effectively minimizing competition between the sexes in the expansive pelagic environment.