Pachygrapsus
Randall, 1840
shore crabs, lined shore crabs
Pachygrapsus is a of small shore crabs in the Grapsidae. The genus comprises approximately 14 distributed across coastal regions, with Pachygrapsus crassipes (lined shore crab) being among the best-studied members. Recent genetic data suggest the genus may be polyphyletic, indicating potential taxonomic revision. Species in this genus occupy intertidal and exhibit complex behavioral for life in dynamic coastal environments.
Pronunciation
How to pronounce Pachygrapsus: //ˌpækɪˈɡræpsəs//
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Habitat
Rocky intertidal zones; occupies crevices and in rocky substrates. Some also occur in salt marsh environments. Megalopae (post-larval stage) occur in nearshore coastal waters where internal waves facilitate shoreward transport.
Distribution
Coastal marine regions; specific distribution varies by . Pachygrapsus crassipes occurs along the Pacific coast of North America. Pachygrapsus transversus has been documented in regions where it serves as to parasitic barnacles. Distribution records from GBIF indicate presence in Denmark (DK) and Norway (NO), though these may represent limited or incidental records for this primarily temperate to tropical coastal .
Host Associations
- Sacculina carcini - Pachygrapsus transversus documented as for this parasitic barnacle (Cirripedia, Rhizocephala)
Life Cycle
Megalopa stage (post-larval settlement stage) exhibits ontogenetic behavioral shifts for recruitment. Megalopae employ selective tidal-stream transport to facilitate shoreward settlement.
Behavior
activity patterns with peak activity during high tides. Territorial defense of specific sites from . selection plasticity related to tidal cycles and risk. Megalopae exhibit selective tidal-stream transport: swimming upward during flood tides and downward during ebb tides, with diel vertical involving nocturnal surface swimming and rapid descent to bottom upon reaching turbulent internal wave zones. Rheotactic responses to current cues observed in megalopal stage.
Similar Taxa
- Hemigrapsus oregonensisCo-occurs with Pachygrapsus crassipes in California salt marshes; studied in context of distribution and coexistence patterns
More Details
Taxonomic Uncertainty
Recent genetic data suggest Pachygrapsus may be polyphyletic, indicating the as currently constituted does not represent a single evolutionary lineage and may require taxonomic revision.
Research Focus
Most detailed behavioral and ecological studies on Pachygrapsus crassipes; data for other in the are sparse.
Sources and further reading
- BugGuide
- Wikipedia
- GBIF taxonomy match
- iNaturalist taxon
- NCBI Taxonomy
- Catalogue of Life
- A rare opportunity to do fall insect collecting in western North America | Beetles In The Bush
- Behavioral Ecology of the Crab, Pachygrapsus Crassipes
- Pachygrapsus Transversus (Gibbes), a New Host of Sacculina Carcini Thompson (Cirripedia, Rhizocephala)
- Behavioral basis of internal-wave-induced shoreward transport of megalopae of the crab Pachygrapsus crassipes
- Lead Burdens and Behavioral Impairments of the Lined Shore Crab Pachygrapsus crassipes
- Observations on Life History of a Gregarine of the Striped Shore Crab, Pachygrapsus crassipes.
- Factors influencing the distribution and coexistence of Pachygrapsus crassipes and Hemigrapsus oregonensis (Decapoda: Grapsidae) in a California salt marsh