Japanese Spider Crab: A Detailed Look at These Enchanting Creatures

Japanese Spider Crabs are fascinating creatures that have captured the imagination of people around the world due to their unique appearance and intriguing characteristics. This article will delve into the various aspects of these remarkable crustaceans, providing an in-depth look at their physical features, habitat, diet, behavior, and more. 

We will also explore the cultural significance of the Japanese Spider Crab and discuss the current conservation efforts to protect this species. Let’s get started!

1. Overview of the Japanese Spider Crab

The Japanese Spider Crab (Macrocheira kaempferi) is a marine crab that belongs to the family Inachidae. Known for their massive size and long, spindly legs, these crabs are truly a sight to behold. They are primarily found in the deep waters around Japan, where they inhabit the rocky ocean floor. 

Japanese Spider Crabs are omnivorous scavengers, feeding on various plant and animal matter. Their unique physical characteristics, behavior, and habitat make them an intriguing subject for marine biologists and enthusiasts alike.

2. Physical Characteristics

Japanese Spider Crabs are the largest known species of crab, with some individuals reaching up to 12 feet in leg span and weighing as much as 40 pounds. Their most striking feature is their long, slender legs, which can be three times the length of their body. 

These legs are not only used for locomotion but also for capturing prey and manipulating objects in their environment.

The hard exoskeleton of the Japanese Spider Crab serves as a protective armor against predators and helps support their massive size. Their body coloration ranges from orange to brown, with white spots covering their legs and carapace. This coloration aids in camouflage, allowing them to blend in with their rocky surroundings.

3. Habitat and Distribution

Japanese Spider Crabs are deep-sea dwellers, typically found at depths of 160 to 1640 feet. They prefer the rocky ocean floor, where they can hide among the crevices and use their long legs to navigate the uneven terrain.

 While they are primarily found in the waters around Japan, they have also been occasionally spotted in other parts of the Pacific Ocean, such as Taiwan and the Philippines. Their thriving temperature is 50 degrees.

4. Diet and Behavior

As mentioned earlier, Japanese Spider Crabs feed on various plant and animal matter. Their diet includes decaying and dead fish, invertebrates, algae, mollusks, and other small marine organisms. They use their long legs and powerful claws to capture prey and tear apart their food.

Japanese Spider Crabs have several predators, including large fish and octopuses. To defend themselves, they rely on their camouflage and hard exoskeleton. When threatened, they can also use their long legs to deliver powerful kicks to deter predators. During the crab-fishing season, humans enjoy eating these crabs as a delicacy.

5. Reproduction and Life Cycle

The mating season for the crabs lasts from January to April, during which they migrate to shallower waters. When mating, the male inserts a spermatophore (sperm packet) into the female as their abdomens press together to complete internal fertilization.

After mating, the female lays thousands of eggs, which she carries under her abdomen until they hatch. The hatching process can take up to 10 days, and the newly hatched larvae are planktonic, meaning they drift into the ocean.

As the larvae grow and develop, they go through several molting stages before reaching their adult form. This process can take several years, with Japanese Spider Crabs reaching sexual maturity around the age of 7 to 10. The average lifespan of a Japanese Spider Crab is around 50 to 100 years, making them one of the longest-lived crab species.

6. Japanese Spider Crab in Popular Culture

The unique appearance and size of the Japanese Spider Crab have made them a popular subject in various forms of media, including documentaries, television shows, and even video games. In Japan, they are sometimes referred to as “taka-ashi-gani,” which translates to “tall-legged crab.” 

They are also featured in Japanese folklore, where they are believed to be the reincarnations of ancient warriors. The name derived from folklore is ‘shinin-gani,’ which denotes “dead man’s crab.” 

7. Conservation and Threats

The population status of the Japanese Spider Crab is currently unknown, as there is limited data on their numbers in the wild. However, they face several threats that could potentially impact their population. 

One of the primary threats is the fishing industry, as these crabs are considered a delicacy in some parts of the world. Overfishing and the use of destructive fishing practices, such as bottom trawling, can significantly impact their habitat and population.

Pollution is another threat to the Japanese Spider Crab, as the deep-sea environment they inhabit is not immune to the effects of human activities. Chemical pollutants, plastic waste, and other forms of pollution can harm their habitat and food sources.

Conservation efforts for the Japanese Spider Crab are currently limited, but there is a growing awareness of the need to protect this unique species. Some measures that could help protect them include implementing sustainable fishing practices, reducing pollution, and conducting further research to better understand their population status and habitat needs.


The Japanese Spider Crab is a captivating and mysterious creature that has captured the interest of people worldwide. Their unique physical features, intriguing behavior, and deep-sea habitat make them fascinating subjects for study and conservation. 

By learning more about these enchanting crabs and working to protect their environment, we can help ensure that future generations have the opportunity to marvel at these remarkable creatures.