Some 490 dead horseshoe crabs”eight times more than usual”have been observed at the Sonehigata tidal flat, one of the largest habitats of the “living fossils” in Japan “ already the highest number of dead horseshoe crabs in the past 20 years.
“Rises in the sea level caused by global warming, shortages of places to lay eggs and a lack of nutrition could have resulted in their deaths,” Hiroko Koike, a researcher from Kyushu University Museum said. “We have to be careful to identify the cause.”
The crab is designated an “endangered species” in Japan, where its population has shrunk as its coastal habitat has been destroyed.
The horseshoe crab “ “kabutogani” in Japanese, meaning literally “warrior helmet crab” ” has recognizable ancestors dating back 450 million years.
Despite the name, however, they are actually not crabs: Their closest living relatives are spiders and scorpions.
Shungo Takahashi, head of the Fukuoka branch of a group that observes and protects the species, told The Asahi Shimbun he estimates there were 2,400 horseshoe crabs at the tidal flat and the 490 dead ones represent about 20 percent of that population. “I am worried that they could lay fewer eggs next year or later,” he said.
