Female blanket octopus
the first half of this clip from the film Oceans captures a gorgeous female blanket octopus
The males of this species are tiny in comparison. From a 2002 paper by Australian biologists:
The first encounter with a live male blanket octopus, Tremoctopus violaceus Chiaie, 1830, illustrates the most extreme example of sexual size-dimorphism in a non-microscopic animal. Females attain sizes of up to 2 m long—almost 2 orders of magnitude larger than the 2.4-cm-long male. Weight ratios between the sexes are at least 10 000:1 and are likely to reach 40 000:1. Sexual selection and the unique defensive strategy of carrying cnidarian stinging tentacles may both have contributed to the evolution of this extreme size- dimorphism. Such dimorphism is not seen in any other animal remotely as large.
If you’re wondering how they mate, it goes like this:
Mature male blanket octopus develop a large modified reproductive arm (hectocotylus) within a spherical pouch (the white swelling between the arms, Fig. 1a). When males mate, this pouch ruptures, sperm is injected into the tip of the modified arm, the arm is severed and passed to the female. The male then almost certainly dies. … Male competition does occur in the blanket octopus since females have been found to contain multiple male arms within their mantle cavities.
The video of the female reminds me of this scene from Memoirs of a Geisha: