Crabs are renowned for their cranky demeanor, but when one considers the extreme conditions under which they must survive, it becomes easier to sympathize with these crotchety crustaceans. One hardship that crabs must endure is changing temperature: a daily swing of 20°C is not unusual for the intertidal zone. Because crabs do not actively maintain a constant internal body temperature, environm...

In the blue crab, Callinectes sapidus, early studies suggested a relationship between smaller crabs, which molt more frequently, and higher rates of infection by the dinoflagellate parasite, Hematodinium perezi. In order to better explore the influence of size and molting on infections, blue crabs were collected from the Maryland coastal bays and screened for the presence of H. perezi in hemoly...

The evolutionary relationships between island and mainland faunas of the 24 species of insular freshwater crabs in the Afrotropical region are reviewed in the light of phylogenetic studies. Twenty insular species of freshwater crabs are endemic, and four are also found on the neighboring mainland of Africa. The Atlantic Ocean islands of Sherbro, Bioko, Príncipe, and São Tomé support five specie...

Bacteria were readily isolated from the hemolymph of a majority (88%) of the blue crabs collected from Galveston Bay, Texas. The hemolymph of most crabs contained moderate (greater than 10(3) bacteria/ml) to heavy (greater than (10(5) bacteria/ml) infections. Large variances were observed in the bacterial number associated with individual crabs, but no significant difference was observed betwee...

The swimming crab Portunus trituberculatus is a durophagous brachyuran. Right-handed crabs are predominant, but left-handed crabs are also found in nature. Left-handedness may arise from loss of the right crusher. We examined whether heterochely (morphology) was correlated with differences in closing force (physical property) and handedness (behaviour). The closing force was stronger in larger ...

Organic and inorganic contaminants can suppress immune function in molluscs and crustaceans. It was postulated that metals could modulate immune function in marine crabs. To test this hypothesis, sublethal effects of mercury (Hg) on cellular immune and biochemical responses of crabs were determined. When crabs were exposed for 14 d to environmentally-relevant concentrations of Hg, changes in im...

To help understand the process of carpel morphogenesis, the roles of three carpel development genes have been partitioned genetically. Mutants of CRABS CLAW cause the gynoecium to develop into a wider but shorter structure, and the two carpels are unfused at the apex. Mutants of a second gene, SPATULA, show reduced growth of the style, stigma, and septum, and the transmitting tract is absent. D...

A reproductive biology study of blue swimming crab, Portunus segnis (Forskal, 1775) in the northern Persian Gulf and Oman Sea, was conducted from May 2010 to October 2011. The results showed that the annual sex ratio is not M: F=1:1, with 51.9 % female. All the five stages of ovarian development of P. segnis were observed throughout the year. The size of ovigerous crabs varied from 103 to 155...

A reproductive biology study of blue swimming crab, Portunus segnis (Forskal, 1775) in the northern Persian Gulf and Oman Sea, was conducted from May 2010 to October 2011. The results showed that the annual sex ratio is not M: F=1:1, with 51.9 % female. All the five stages of ovarian development of P. segnis were observed throughout the year. The size of ovigerous crabs varied from 103 to 155...

Predator – prey interactions are often highly co-evolved, with selection over time for prey with morphological and behavioral traits that minimize predation risk. Consequently, in many environments prey choose among potential habitats according to their refuge value. It is unclear, however, when presented with new habitats, if prey are able to evaluate the predation risk of these relative to fa...