evolucija

**VIDEO AVAILABLE: CONTACT INFO@COVERMG.COM TO RECEIVE**BY MARK WORGANOctopuses have a special 'sex arm' they use to identify partners by taste and mate with them, according to researchers at Harvard University.The findings, published in the journal Science, show that males can locate and fertilise females without seeing them, sometimes mating at arm's length.Scientists say the research sheds new light on how these largely solitary animals reproduce, and may help explain how new species evolve.Male octopuses have eight arms, but one - known as the hectocotylus - is specially adapted for reproduction."Male octopuses use a specialized arm called the hectocotylus to identify females and navigate their internal organs to reach the oviduct and deliver sperm," the researchers, led by lead author Pablo Villar, write in their paper.During mating, the arm searches for the female's mantle cavity and deposits packets of sperm, known as spermatophores. The researchers found that the arm is lined with receptors similar to those used by other arms to explore the seabed.Octopus limbs are highly sensitive, with each suction cup containing thousands of sensory cells. Much of the animal's nervous system is distributed throughout its arms, allowing them to act independently of the brain.To test how the animals use these abilities, scientists observed mating behaviour in the California two-spot octopus (Octopus bimaculoides).Males and females were placed on opposite sides of a tank, separated by a barrier with small openings. Despite being unable to see each other, males were able to extend their specialised arm through the divider, locate the female and begin mating.The study found that such interactions could take place even in complete darkness. When two males were paired, however, no mating attempts were observed, suggesting females emit a specific chemical signal.Further experiments pointed to the hormone progesterone as a key factor.Research

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