Japanese Spider Crabs hang out on the sea floor where they feed off of other crustaceans and material of dead animals that has floated downwards. They reportedly can live up to 100 years, making them a very long-lived species.
Japanese Spider Crabs have not been evaluated by the IUCN, but they are fished for consumption purposes. However, the number caught has gone down in recent years due to protection programs. Fishing continues in Saruga Bay, but overfishing in that area has caused fishermen to look deeper and deeper for these large crustaceans.