A research group led by Professor Yuichi Hirose of the University of the Ryukyus has revealed that female larvae of the Umikuwagata family are attracted to adult males and prolong the larval stage without males.
Gnathiidae is a crustacean with the same legs as pill bugs and ligia exotica.A marine animal with a length of several millimeters, a male has a large jaw.Females have a once-in-a-lifetime breeding opportunity and die shortly after giving birth, but males can breed with multiple females by the time they die.The research group explored the mechanism of encounters between males and females.
As a result of the experiment, it was found that adult males attract female larvae by sex pheromones.Gnathiidae larvae often swim to suck blood and escape from natural enemies, but adults do not move very actively.Therefore, it is considered more efficient for female larvae to search for adult males and move than for adult males to search for females.
In addition, female larvae differed greatly in larval period depending on whether males were nearby or not.In single breeding, males molt and transform into adults in about 18 week and females in about 8 month, but when female larvae are bred together with male larvae and adult males, they transform into adult females in an average of XNUMX days (minimum XNUMX days). bottom.In general, isopod females can mate only when the exoskeleton is soft immediately after molting, and if there is no adult male nearby at that time, they cannot reproduce and may die.Prolonging the larval period by female larvae appears to be important to prevent reproductive failure.
There are reports of "postponement of metamorphosis of females" in other crustaceans, but the larval period that can be extended is about several hours to 3 days. This is the first time that Gnathiidae has discovered a postponement of metamorphosis for more than two weeks.It is said that the breeding pattern of Gnathiidae has evolved so that females that can breed only in a short period of time immediately after metamorphosis once in a lifetime and males that can breed with multiple females until death meet and succeed in breeding at the required timing.
