Check out this video of an Argonaut octopus, which was netted accidentally by fishermen in waters off Los Angeles.
The presence of this octopus in temperate waters is highly unusual as these pelagic creatures are typically found far offshore in tropical and sub-tropical seas.
The baseball-sized octopus was taken to Cabrillo Marine Aquarium in San Pedro, California, which posted the footage below onto YouTube (scroll down for video). It's particularly interesting as it shows the octopus leaving its beautiful ammonite-like shell. The female of the species makes the laterally-compressed calcareous shell with one chamber that's used as a brood pouch for the eggs. She is much bigger than the male (females reach around 45cm/18" in size, while males reach just 2.5cm/1" are shell-less.
The shells are highly prized by collectors.
Cabrillo Marine Aquarium says: "(The) male has one of its eight arms (the third) highly modified to carry sperm to female.
"The modified arm in the male is called a hectocotylus and during mating this arm breaks away from the male and crawls into the female to remain until the female is ready to fertilise her eggs.
"When first discovered in the early 1800s the hectocotylus arm was thought to be a parasitic worm and was given the species name of Hectocotylus (therefore the origin of the term hecotocotylus arm of cephalopods)."
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