Chionoecetes tanneri (chio-snow and ioketes-inhabitant) are commonly referred to as Grooved Tanner Crabs and related to the more commercially important snow crab, C. opilio. C. tanneri is from the infraorder Brachyura (short-tailed) or the true crabs (Phylum Arthropoda, Subphylum Crustacea, Class Malacostraca, Order Decapoda, Suborder Plecyemata, Infraorder Brachyura, Superfamily Majioidea, Family Majidae). Tanners may live to an estimated maximum age of 14 years feeding upon a wide assortment of marine life including worms, clams, mussels, snails, crabs, other crustaceans, and fish parts. Females mate with an adult male for the first time during her last molt, mating in the softshell condition while grasped by the male. Older hardshelled females are also mated by adult males, but in the absence of a male they are capable of producing an egg clutch with sperm stored from a previous mating. A female Tanner crab may deposit 85,000 to 424,000 eggs in a clutch. Hatching occurs late the following winter and spring with the peak hatching period usually during April to June, coinciding with the spring bloom. After ~60 days the larvae lose their swimming ability and settle to the ocean bottom. After numerous molts and several years of growth, females mature at approximately 5 years of age. Males will mature at about 6 years.
I have had a long standing interest in the body size of organisms, especially those from the deep sea. I experienced a little euphoria when I first encountered this fine specimen las year. Crabzilla is a female and substantially larger than most of her kind with a carapace width of 15.30 cm (1206.5g, A big lady indeed!). In another study that contained more than 750 adults none reached carapace widths over 14.5 cm (mean=11cm). The two pictures display Crabzilla and a typical size tanner (note the white line is the same length in both pictures). She was captured at 1035m in January in Monterey Canyon and lived in an aquarium here at the Monterey Bay Aquarium Research Institute for better part of a year.
In the Gulf of Mexico, we commonly see another majid crab, Rochinia tanneri. Perhaps there is only one true majid tanneri??
They can get big, but the largest I’ve seen personally had about 3-4 inch carapace width.