Macrocheira kaempferi
Fast Facts
- May live to be one hundred years old
- Largest known living arthropod
- Their Japanese name, Taka-Ashi-Gani, translates to “tall legs crab”.
Range
Pacific side of Japanese Islands, Konshu & Kyushu
Habitat
Depths of 500-1,000 feet
Size
Body 15 inches wide with leg span up to 15 feet
Nutrition
Carrion meat and decaying matter on the seabed
Characteristics
The crab’s carapace is pear-shaped, narrowing towards the head, with a range of dark orange to light tan. Females tend to have a wider abdomen. Although the legs continue to grow, the main body remains relatively unchanged throughout adulthood. The walking legs hook inward to assist with hooking and grasping. The long legs are considered weak, and giant spider crabs are often seen missing one leg.
Behavior
As a large decorator crab, the Japanese spider crab adorns its exoskeleton with algae and sponges to increase its camouflage to hide from predators like octopuses and fish. They are omnivorous scavengers, feeding on any matter they can find on the seafloor and occasionally hunting for small invertebrates.
Reproduction
The Japanese spider crab will migrate to shallow waters (160 feet) during the breeding months of Spring (January to April). Males insert sperm into the female abdomen using their first two chelipeds (claws). Females lay up to one million eggs. After a hatching duration of ten days, the larval stage begins. Only a few of the million offspring will survive to adulthood. This species goes through two zoeal stages (planktonic) and one megalopa stage, all of which happen rapidly.