A Different Kind of Argonaut: Mysterious Visitor Spotted in Adriatic Sea

Total Croatia News

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May 20, 2018 – A peculiar creature was found by a surfer in the waters of Pelješac 

The village of Viganj on Pelješac peninsula had a special visitor a couple of days ago. Morski received several photos from a reader named Zlata Radovanović who was surfing off the coast of Viganj when she came upon a strange little sea creature.

The curious traveller looked like a clam or a sea snail at first glance, but it turned out it was actually an argonaut. And not the mythical kind (though you might remember the link between the legendary sailing crew and Croatia), but an animal, very much alive and kicking. Lively enough to have found its way to the Adriatic Sea, even though it usually resides in tropical and subtropical waters.

Argonauts are a group of pelagic octopuses, meaning they live in the open ocean. Unlike other members of their kind, they don’t live on the seabed but instead prefer to dwell closer to the surface. Their resemblance to clams is a result of their unique feature: a thin, transparent eggcase their body is encased in. Females secrete the case and deposit their eggs in it; while they can measure 10 cm in size and create shells up to 30 cm, males are known to reach a maximum of 2 cm in size.

And for the final fun fact, argonauts have quite an intriguing reproduction method. The male uses a modified arm called the hectocotylus to fertilise the female – an arm that becomes detached from his body as soon as it enters the female’s mantle. That’s why biologists formerly thought the tiny object spotted in females was a parasitic worm; in the 19th century, the first male specimen were discovered and described, and the mystery was solved.

All things considered, not an average visitor!



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