Randallia ornata

(Randall, 1840)

globose sand crab, purple globe crab

Randallia ornata is a true crab in the Leucosiidae, commonly known as the globose sand crab or purple globe crab. It inhabits sandy beaches along the eastern Pacific coast from Northern California to Baja California, Mexico. The is notable as a for an undescribed nemertean in the Carcinonemertes, which acts as an with rates reaching 70% in crab .

Pronunciation

How to pronounce Randallia ornata: //rænˈdæliə ɔrˈneɪtə//

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Identification

Distinguished from other leucosiid crabs by its globose, rounded body form and purple coloration. The name 'ornata' (ornamented) suggests distinctive surface features, though specific diagnostic characters are not documented in available sources.

Habitat

Sandy beaches along the Pacific coast. The burrows in sand substrates in intertidal or shallow subtidal zones.

Distribution

Eastern Pacific: Northern California (USA) south to Baja California (Mexico). Records from East Pacific region generally.

Host Associations

Carcinonemertes sp. - Undescribed nemertean ; with 70% in crab . occur in crab egg masses; regressed adults found under of post-ovigerous females; encysted on of non-ovigerous females and occasionally males. rates vary by reproductive status: 85% in ovigerous females, 67% in post-ovigerous females, 45% in males. Intensities up to 32 worms per crab.

Ecological Role

for nemertean ; ovigerous females serve as for . The crab's reproductive biology creates distinct microhabitats that structure the worm's stages.

More Details

Parasite ecology

The nemertean Carcinonemertes sp. shows differential patterns correlated with reproductive status. Worms secrete spiral tubes and reach 10 mm in length. This host- system represents one of the better-documented cases of nemertean-crab associations in the Leucosiidae.