where does the spider crab live

Where Does the Japanese Spider Crab Live? A Look at the Habitat of this Colossal Crustacean

The Japanese spider crab is one of the most impressive creatures in the ocean. With its spindly, spider-like legs spanning up to 12 feet, this giant arthropod cuts an intimidating figure as it scuttles across the seafloor But where exactly does this mammoth crab call home? In this article, we’ll explore the habitat and range of the Japanese spider crab.

The Japanese spider crab (Macrocheira kaempferi) is mostly found off the southern coast of Japan, primarily around the island of Honshu. Their range stretches from Tokyo Bay down to Kagoshima Prefecture. They have also been spotted off the coast of Taiwan.

These crabs prefer to live at depths of 164 to 1,640 feet underwater. However, during mating season they migrate to shallower depths of around 160 feet. This allows them to spawn in slightly warmer waters of around 50°F.

Spider crabs are bottom dwellers, inhabiting the rocky and sandy ocean floor. They like to tuck themselves into holes, crevices and vents down in the deep. Their bumpy, mottled carapace acts as camouflage, helping them blend into the rocks.

As adults, the crabs don’t have many predators to hide from. Their formidable size deters most animals from seeing them as prey. However, the young spider crab larvae need to evade predators in the surface waters. Hiding in the depths helps protect them during this vulnerable stage.

The specific habitat requirements of adult spider crabs are not fully known. However, they are regularly observed at a depth of 980 feet in Suruga Bay, where water temperatures are around 50°F. Based on aquarium studies, they seem to tolerate temperatures between 43-61°F, with an optimal range of 50-55°F. Colder temperatures are preferred.

Spider crabs are only found in the northwest Pacific Ocean near Japan and Taiwan. Attempts to introduce them in other regions have failed. After being transported to the United States and Europe for aquariums, they survived for up to two years but did not spawn and died.

This limited range suggests the crab has very specialized environmental needs. The cooler deep-sea temperatures found off southern Japan provide an ideal habitat. Establishing populations outside of their native waters has proven difficult.

Beyond temperature, factors like ocean currents, salinity, oxygen levels and food availability likely contribute to the spider crab’s habitat restrictions. The conditions around Japan produce an optimal ocean environment that can’t easily be replicated elsewhere.

Within Japan, spider crab populations are concentrated in Pacific-facing areas with rocky or sandy ocean floors and access to deep, cold waters. Bays, inlets and coastal shelves provide the right mix of depth, temperature and substrates for them to settle. Suruga Bay is a particularly well-known habitat, with an abundance of crabs found seasonally at depths of around 1,000 feet.

Some key areas sustaining spider crab populations include:

• Suruga Bay – Known for large seasonal population at depths of around 1,000 feet, where waters are 50°F.

• Tokyo Bay – Northern extent of range.

• Kagoshima Prefecture – Southern limit of population distribution.

• Coastal regions of Honshu – Most of population concentrated along Japan’s largest island.

• Taiwan – Specifically off the town of Su-ao, an outlying population exists.