Geographic Range

The Giant Japanese spider crab can be found in the Pacific Ocean near Japan. They live in depths of 50-300m (150-1000feet)(Encyclopedia Britannica Online).

Biogeographic Regions: oriental (native ).

Habitat

Giant grabs are found in the depths of the Pacific Ocean surrounding Japan. They tend to prefer the deeper parts of the ocean, such as vents or holes. This makes them hard to catch by fisherman, but they are not a rare food item in the Orient (Encyclopedia Britannica Online).

Aquatic Biomes: oceanic vent .

Physical Description

The giant spider crab is one of the largest arthropods we know. They have been known to measure 3.7 m from the tip of one outstreached claw to another. Their body usually grows to about 37cm (15in) across(Encyclopedia Britannica Online). Spider crabs get their name from their likeness to a spider. They have rounded bodies that are covered with stubby projections (tubercles) and long spindly legs (Bliss, 1982).

Reproduction

Giant crabs have separate sexes, like many crustaceans. Males are larger than females and have bigger pinchers (Warner, 1976). Sperm of male crabs are held in a case, or spermatophore. Spermatophores are transfered to the female by the first and second abdominal appendages during mating. After fertilization, the female crab carries the eggs attached to the abdominal appendages. A cement is secreted by the egg-carrying setae to bind them to the abdominal appendages. When the eggs hatch, the young crabs look nothing like their parents. During the larval stage, or the zoea, the baby crabs are small, transparent organisms with round, legless bodies. They usually swim at the surface of the ocean. During their growth stage, they tend to shed their skin several times. When the body and legs begin to form and appear more crab-like, the young crab is in the megalops stage. During this stage, though, the abdomen is large and not folded up. The crab continues to molt it's skin until it takes on a form that is very similar to the adult (Soltanpour-Gargari, 1989).

Behavior

Giant crabs move along the ocean floor at a very slow pace, while scooping up food (Bliss, 1982). Crabs attach sponges and other similar animals to their shells to ward off predators, such as octopuses. Even though the giant crab is one of the largest arthropods, it still needs protection from larger animals (Warner, 1976).

Food Habits

Giant crabs are omnivorous and sometimes act like scavengers. They have also been know to be vegetarians and predators (Warner, 1976). Some giant crabs scrape the floor of the ocean for plants and algae, while others pry open the shells of mollusks to eat the fleshy meat (Anonymous, 1998).

Economic Importance for Humans: Negative

Giant crabs have large pinchers which can be painful.

Economic Importance for Humans: Positive

If caught, giants crabs prove to be a delicious meal.