Tuberculate Pear Crab

Pyromaia tuberculata

The Tuberculate Pear Crab, part of the Inachoididae family, is a bottom-dwelling species that typically resides on continental shelves. It is characterized by a carapace with granular and tuberculate texture, and a small spine on its first abdominal segment. Adults can grow to a carapace length of up to 20 mm and a width of about 18 mm. This species progresses through nine post-larval stages, with mature females identifiable by their rounded abdominal plates designed to carry eggs. Originally from the Pacific coast of North America, this crab has expanded its range to areas such as Argentina, Australia, Brazil, Japan, and New Zealand. It is found in coastal and estuarial waters, with larvae drifting freely at depths up to 18 meters, while adults inhabit mud to sandy-mud bottoms reaching depths of 412 meters. The Tuberculate Pear Crab is known to establish itself in new regions, especially in environments with low oxygen levels, where it can outcompete native species. Divers might spot this crab concealed among stones or on the seabed. It is particularly prevalent in nutrient-rich waters like Tokyo Bay, where it adapts well despite periodic low oxygen conditions.