Lithodidae

Samouelle, 1819

King Crabs, Stone Crabs

Genus Guides

Cryptolithodes(king crabs)
Paralithodes(king crab)

Lithodidae is a of large, cold-water decapod crustaceans commonly known as king crabs or stone crabs. Members possess a crab-like body form within the otherwise hermit crab-associated infraorder Anomura, representing an independent evolutionary transition to the crab . The family includes commercially important such as the red king crab (Paralithodes camtschaticus) and encompasses both deep-water and intertidal across cold seas of the Northern and Southern Hemispheres.

Lithodidae by (c) Erin McKittrick, some rights reserved (CC BY), uploaded by Erin McKittrick. Used under a CC-BY license.

Lithodidae by (c) Erasmo Macaya Horta, some rights reserved (CC BY), uploaded by Erasmo Macaya Horta. Used under a CC-BY license.

Paralithodes by (c) Jean, some rights reserved (CC BY). Used under a CC-BY license.

Pronunciation

How to pronounce Lithodidae: /lɪˈθɒdɪˌdiː/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Distinguished from true crabs (Brachyura) by the folded, reduced and asymmetrical pleopods adapted for abdominal rather than swimming. Differs from other Anomura by the fully calcified, crab-like body form without dependence on gastropod shells for protection. Presence of spiny, tuberculate and robust legs separates Lithodidae from the closely related Chirostylidae (squat lobsters), which have a more compressed body and long .

Images

Appearance

Large-bodied decapods with a broad, calcified covering the ; reduced and folded tightly beneath the body, unlike the extended abdomen of hermit crabs. Carapace typically armed with spines, , or other ornamentation; legs robust and spiny, with the first pair modified as claws (chelipeds). Body plan convergent with true crabs (Brachyura) despite phylogenetic placement within Anomura.

Habitat

Predominantly cold-water marine environments ranging from rocky intertidal zones to deep continental slopes. Some occupy muddy substrates at 200-500 m depth, while others inhabit shallower coastal waters. Depth distribution varies seasonally in some species, with documented between 100-200 m and 200-400 m depths.

Distribution

Circumpolar distribution in cold seas of both hemispheres. Documented from the Barents Sea, Bering Sea, coastal waters of British Columbia, Namibia, the Galapagos archipelago, western Mexico, Argentina, and Sub-Antarctic waters. Specific records include: Paralomis nivosa from the Philippines; P. makarovi from the Bering Sea; P. alcockiana from South Carolina; Lithodes galapagensis from the Galapagos; P. spinosissima from South Georgia Island to the Drake Passage with northern extension to Argentina.

Seasonality

Reproductive seasonality varies by and latitude. Lithodes ferox exhibits winter mating (July-September) with peak ovigerous females during this period; Hapalogaster dentata spawns October-November. Some species show seasonal bathymetric correlated with .

Life Cycle

Development includes of approximately 110 days in some . Females eggs on pleopods; ovigerous females have been observed year-round in some species with seasonal peaks. Sexual maturity reached at 2+ years in smaller species. recruitment occurs in specific depth zones, with Lithodes ferox juveniles (10-30 mm length) recruiting in shallow water (<200 m) during September-October.

Behavior

Pre-oviposition mate guarding documented in multiple : males grasp or cover ripe females for 2-3 days prior to female and spawning. Seasonal bathymetric observed in some species, with larger males moving to shallower depths for mating while females and smaller males remain in deeper water. Size-related depth stratification present in some .

Human Relevance

Multiple support significant commercial fisheries due to large body size and desirable meat. The red king crab (Paralithodes camtschaticus) is the most economically important species and has been introduced to the Barents Sea. Deep-water species are increasingly subject to exploration for potential fishery development.

Similar Taxa

ChirostylidaeAlso within Galatheoidea and superficially crab-like, but distinguished by compressed body form, long , and often dorsoventrally flattened ; typically associated with hard substrates and coral rather than soft sediments
Brachyura (true crabs)Convergent body form but phylogenetically distant; true crabs have symmetrical pleopods and a reduced that is not folded beneath the body in the same manner; position and larval development also differ
ParapaguridaeAnother anomuran with some crab-like members, but typically retain shell-dwelling habits or have soft, asymmetrical ; less robust structure than Lithodidae

More Details

Taxonomic placement

Despite the 'king crabs' and crab-like appearance, Lithodidae belongs to the infraorder Anomura, which is dominated by hermit crabs. The crab-like body form evolved independently within this lineage through carcinization—the evolutionary process of transforming a hermit crab-like ancestor into a crab-like form.

Subfamily diversity

The contains at least two : Lithodinae (including Lithodes and Paralithodes) and Hapalogastrinae (including Hapalogaster). These subfamilies differ in body size, preference, and reproductive , though they share the characteristic pre-oviposition mate guarding behavior.

Biennial reproduction

At least one , Lopholithodes foraminatus from British Columbia, exhibits with embryonic , suggesting complex reproductive strategies may be widespread in the .