New species of crabs with asymmetric reproductive units identified
A team of researchers from the National University of Singapore (NUS) and Ryukyu University recently identified and described a strange new genus and species of xanthid crab found on Okinawa Island in the Ryukyu Islands , in Japan. Named Mabui’s calculus, it is unique among the 7,800 crab species known to have strongly asymmetric male and female reproductive structures!
“Male crabs have a pair of reproductive parts called gonopods while females have a pair of vulvae. All crabs mate in a ‘missionary position’, so the gonopods pump sperm into the females for internal fertilization. eggs. This was accepted orthodoxy until our discovery – a small Japanese crab evolved to do this very differently! explained Professor Peter Ng, a world expert on crustaceans and director of the Lee Kong Museum of Natural History Chian at the NUS.
Researchers first saw this nondescript little xanthoid crab – which was about 6 millimeters wide – more than a decade ago in the high-energy surf areas of Okinawa, Japan.
“When we took a closer look at these crabs, we found that both male and female crabs had markedly asymmetrical male gonopods and female vulvae – one member of each pair was normal while the other was sharply reduced. assorted pairs! The right male gonopod is long and well developed, while the left one is much smaller. The left female vulva is large and round, while the right is lost in most females. way for crabs to mate efficiently The evolution of asymmetric spawning parts is not known for any crab, and it is truly amazing in nature, ”Professor Ng added.
The research team collected more than 50 specimens, including females with eggs, to conduct further studies. It took scientists a decade of study and comparison to decipher what this “sexy crab” – scientists’ nickname for the animal – and to give it a formal scientific name – Mabui’s calculation.