<P> If they are provoked, they quickly change color, becoming bright yellow with each of the 50 - 60 rings flashing bright iridescent blue within a third of a second as an aposematic warning display . In the greater blue - ringed octopus (Hapalochlaena lunulata), the rings contain multi-layer light reflectors called iridophores . These are arranged to reflect blue--green light in a wide viewing direction . Beneath and around each ring there are dark pigmented chromatophores which can be expanded within 1 second to enhance the contrast of the rings . There are no chromatophores above the ring, which is unusual for cephalopods as they typically use chromatophores to cover or spectrally modify iridescence . The fast flashes of the blue rings are achieved using muscles which are under control . Under normal circumstances, each ring is hidden by contraction of muscles above the iridophores . When these relax and muscles outside the ring contract, the iridescence is exposed thereby revealing the blue color . </P> <P> In common with other Octopoda, the blue - ringed octopus swims by expelling water from a funnel in a form of jet propulsion . </P> <P> The blue - ringed octopus diet typically consists of small crabs, and shrimp, but they may also feed on fish if they can catch them . The blue - ringed octopus pounces on its prey, seizing it with its tentacles and pulling it towards its mouth . It uses its horny beak to pierce through the tough crab or shrimp exoskeleton, releasing its venom . The venom paralyses the muscles required for movement, which effectively kills the prey . </P> <P> The mating ritual for the blue - ringed octopus begins when a male approaches a female and begins to caress her with his modified arm, the hectocotylus . A male mates with a female by grabbing her, which sometimes completely obscures the female's vision, then transferring sperm packets by inserting his hectocotylus into her mantle cavity repeatedly . Mating continues until the female has had enough, and in at least one species the female has to remove the over-enthusiastic male by force . Males will attempt copulation with members of their own species regardless of sex or size, but interactions between males are most often shorter in duration and end with the mounting octopus withdrawing the hectocotylus without packet insertion or struggle . </P>

How do blue ringed octopus catch their prey
find me the text answering this question