Seitz R, Vilpoux K, Hopp U, Harzsch S & Maier G. 2005. Ontogeny of the Marmorkrebs (marbled crayfish): a parthenogenetic crayfish with unknown origin and phylogenetic position. Journal of Experimental Zoology A 303(5): 393-405. http://dx.doi.org/10.1002/jez.a.143Abstract
Development, growth, and egg production of the Marmorkrebs (marbled crayfish), a crayfish with parthenogenetic reproduction, uncertain geographic origin, and taxonomic position, was studied under laboratory conditions. Length and weight increments strongly depended on temperature being highest at 30°C, and lowest at 15°C. At 25°C, cephalothorax length and weight increased by 17.5 mm and 1700 mg, respectively, in the course of 150 d, whereas at 15°C these parameters increased by only 7 mm and 100 mg during the same period of time. Photoperiod slightly affected growth at 25°C. During growth experiments, mortality was lower at 20°C compared to higher (25°, 30°C) or lower temperatures (15°C), and lower under short-day than under long-day conditions. Females matured early (at an age of 141-255 d, a cephalothorax length of 14-21.5 mm, and a weight of 0.63-2 g) compared to other crayfish species. Reproductive females with a cephalothorax length of between 25-35 mm produced large clutches (up to 416 eggs) and brooding periods varied between 22 and 42 d. In order to establish a staging scheme for Marmorkrebs embryos, embryos were photographed, externally visible ontogenetic events charted, and dissected embryos stained with a nuclear dye. These experiments indicate that their development is virtually identical to that of other crayfish. In conclusion, these results and others show that the Marmorkrebs may be taken as a representative valid model organism for future developmental studies on Crustacea.
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