Uca

Leach, 1814

Narrow-fronted Fiddler Crabs, fiddler crabs, calling crabs

Uca is a of semi-terrestrial marine crabs comprising approximately 100 , commonly known as fiddler crabs or calling crabs. Males are distinguished by one greatly enlarged used for visual displays and combat. These small crabs inhabit intertidal zones worldwide, where they construct burrows and feed on material in surface sediments. Their burrowing activity contributes significantly to sediment turnover and in coastal .

Uca by (c) James M. Maley, some rights reserved (CC BY), uploaded by James M. Maley. Used under a CC-BY license.

Uca pugilator and hole by Ianaré Sévi. Used under a CC BY-SA 3.0 license.

Fiddler crabs (10.3897-zookeys.943.52773) Figure 2 by Masunari S, Martins SB, Anacleto AFM (2020) An illustrated key to the fiddler crabs (Crustacea, Decapoda, Ocypodidae) from the Atlantic coast of Brazil. ZooKeys 943: 1-20. https://doi.org/10.3897/zookeys.943.52773. Used under a CC BY 4.0 license.

Pronunciation

How to pronounce Uca: /ˈjuːkə/

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

Identification

Males possess one dramatically enlarged cheliped (), typically the right, used for waving displays and combat; females have two small claws of equal size. is roughly square with a narrow . Small body size, with largest reaching slightly over two inches across. Distinguished from ghost crabs (Ocypode) by the single enlarged claw in males and more compact body form.

Images

Habitat

Intertidal mudflats, sandflats, and brackish lagoons along sea beaches. Occupies zones from mid-tide level to upper shore. Substrate preferences vary by : some prefer firm substrates, others softer mud.

Distribution

Worldwide distribution in tropical and subtropical coastal regions. Present in Hong Kong waters, eastern and western Atlantic coasts, Indo-Pacific, and eastern Pacific. Records include Zanzibar, Tanzania.

Diet

feeders that consume material in surface sediment during low tide. Food is processed through specialized mouthparts.

Life Cycle

Larval development includes planktonic zoea and megalopa stages before settlement to benthic . Recruitment occurs seasonally. Females incubate in burrows and release on spring tides.

Behavior

Males perform rhythmic waving displays for mate attraction and recognition. Complex territorial includes burrow construction, defense, and combat between males for burrow ownership. Activity are synchronized with tidal cycles, with crabs emerging during low tide to feed and engage in social behaviors.

Ecological Role

Biourbators through extensive burrowing activity. Burrow construction contributes to sediment turnover, aeration, and in intertidal .

Similar Taxa

OcypodeGhost crabs share Ocypodidae and similar intertidal , but lack the single enlarged characteristic of male Uca; Ocypode are generally larger and more

More Details

Taxonomic Note

Approximately 100 recognized; has undergone taxonomic revision with some former species now placed in related genera such as Gelasimus and Tubuca by some authorities

Uca