Wilson, Natasha J; Williams, Craig R
Consumption of amphibian eggs and larvae by crayfish has been widely reported despite many amphibians being unpalatable and/or toxic to other predators. The aim of this review was to gather information regarding the consumption and/or avoidance of toxic amphibians by these omnivores. We then appraised the extent of toxin consumptive ability in terms of crayfish phylogenetic history so as to speculate as to the evolutionary history of this trait. Reports indicating an ability to tolerate amphibian toxins were collected and reviewed for 12 freshwater crayfish species. In reviewing these, we have established that freshwater crayfish appear to be tolerant of a range of toxic amphibians, often consuming large numbers of eggs and larvae without lethal or apparent sublethal effects. Toxin tolerance was evident within both superfamilies (Astacoidea and Parastacoidea) suggesting that tolerance may be a primitive trait in freshwater crayfish. PMID:24556015
Luquet, Gilles; Fernández, María S.; Badou, Aïcha; Guichard, Nathalie; Roy, Nathalie Le; Corneillat, Marion; Alcaraz, Gérard; Arias, José L.
Crustaceans have to cyclically replace their rigid exoskeleton in order to grow.Most of them harden this skeleton by a calcification process. Some decapods (land crabs, lobsters and crayfish) elaborate calcium storage structures as a reservoir of calcium ions in their stomach wall, as so-called gastroliths. For a better understanding of the cyclic elaboration of these calcium deposits, we studied the ultrastructure of gastroliths from freshwater crayfish by using a combination of microscopic and physical techniques. Because sugars are also molecules putatively involved in the elaboration process of these biomineralizations, we also determined their carbohydrate composition. This study was performed in a comparative perspective on crayfish species belonging to the infra-order Astacidea (Decapoda, Malacostraca): three species from the Astacoidea superfamily and one species from the Parastacoidea superfamily. We observed that all the gastroliths exhibit a similar dense network of protein-chitin fibers, from macro- to nanoscale, within which calcium is precipitated as amorphous calcium carbonate. Nevertheless, they are not very similar at the molecular level, notably as regards their carbohydrate composition. Besides glucosamine, the basic carbohydrate component of chitin, we evidenced the presence of other sugars, some of which are species-specific like rhamnose and galacturonic acid whereas xylose and mannose could be linked to proteoglycan components. PMID:24970155