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An alien marine animal with sperm-shaped organisms in its ‘belly’ and tiny ‘appendages’ has been identified after biologists first spotted an image of it in 2018.
The tiny swimmer, caught off the coast of Japan, stunned experts who were unsure whether it was a worm, mollusk or crustacean.
After deeper analysis, researchers from the University of Vienna discovered that the animal was a colony of two parasitic larval worms that swam as one.
The appendages turned out to be individual organisms called “sailors” anchored to a blob carrying more than 1,000 passengers.
The two parasites created a prey-like swimmer that would infect the intestines of an unsuspecting host.
The little swimmer, caught off the coast of Japan, stunned experts who were unsure whether it was a worm, mollusk or crustacean
The colony was discovered by Japanese underwater photographer Ryo Minemizu, who spotted the ladybug-sized creature 15 meters below the surface while swimming off the coast of Kiyan Cape in Okinawa.
Minemizu posted the images to his Instagram account, attracting the interest of hundreds of biologists, all of whom failed to correctly identify the image.
Igor Adameyko, a developmental neurobiologist at the Medical University of Vienna, contacted Minemizu for a sample and unraveled the mystery.
Adameyko analyzed the specimen and determined that the passengers and sailors belong to the digenean family Acanthocolpidae, probably the genus Pleorchis.
Pleorchis is a type of flatworm that commonly infects the intestines.
The scientist conducted a DNA test that confirmed that the sailors and passengers belonged to the same species.
After deeper analysis, researchers from the University of Vienna determined that the animal was a colony of two parasitic larvae worms that swam as one.
The appendages turned out to be individual organisms called “sailors” anchored to a blob carrying more than 1,000 passengers.
“The body of the passengers is blunt with a collar-like bulge at the front, while the body of the sailors is dorsoventrally flattened,” reads the study published in Current biology.
It seemed that the passengers were the contaminating agent, and the sailors simply took them to a host.
Adameyko found that the sailors had different collective activity regimes, as they could beat their tails in synchrony, creating joint pulsating or jumping movements.
This gave rise to the idea that it was one swimming animal.
The sailors carry the passengers through the water in search of a suitable host, but have no penetrating organs and their fate is doubtful.
Scientists have proposed two hypotheses about their fate.
“They sacrifice themselves to provide passenger transportation,” the study said.
‘This scenario implies a strong division of labor between sailors and passengers.
‘Another option is for sailors to continue their lives in the fish that have eaten an aggregate.
‘Because they lack penetrative organs, cercariae can go straight to the digestive system and develop into a sexual adult worm.’