Elevated summer temperature effects on megalopal and early juvenile development in the Dungeness crab,Cancer magister

1996 ◽  
Vol 53 (9) ◽  
pp. 2076-2079
Author(s):  
S D Sulkin ◽  
E Mojica ◽  
G L McKeen



2008 ◽  
Vol 27 (4) ◽  
pp. 901-906 ◽  
Author(s):  
Terry D. Beacham ◽  
Janine Supernault ◽  
Kristina M. Miller


1975 ◽  
Vol 30 (1) ◽  
pp. 72-78
Author(s):  
J. S. Lee ◽  
D. K. Pfeifer


1979 ◽  
Vol 79 (1) ◽  
pp. 47-58
Author(s):  
D. G. McDONALD ◽  
B. R. McMAHON ◽  
C. M. WOOD

Enforced activity causes a marked depression of haemofymph pH in Cancer magister. Both lactate concentration and PCOCO2 of the haemolymph are elevated immediately following exercise but resting PCOCO2 is restored within 30 min whereas resting lactate levels are not restored for at least 8 h. The haemolymph acid-base disturbance is caused largely by elevated haemolymph lactate levels but a Davenport analysis based on measurements of pH and total CO2 reveals a marked discrepancy between the amount of metabolic acid buffered by the haemolymph and the lactate anion concentration. This appears due to a more rapid release of lactate from the tissues than H+ ions produced with lactate.



Author(s):  
Sven Thatje ◽  
Gustavo A. Lovrich

The decapodid and first two juvenile stages of the caridean shrimp Campylonotus vagans from the Subantarctic Beagle Channel (Tierra del Fuego, Argentina) are described and illustrated in detail. The complete larval and early juvenile development of this species from rearings under controlled laboratory conditions were analysed. Zoeal morphology in two stages of an abbreviated development was identical to a description from plankton and hatched larvae of a previous work, and therefore we only compare and discuss slight morphological variations in this study. The first juvenile is large and already resembles some features of adults, lacking all ventral rostral and the fourth dorsal rostral spine only which appears in the following stage, and the second pereiopod not yet being as predominant as in adults. Sexual determination is not yet possible up to the described second juvenile stage. The abbreviated larval development in a Subantarctic shrimp species is discussed as an adaptation to low temperatures and pronounced seasonality.



The Auk ◽  
2009 ◽  
Vol 126 (3) ◽  
pp. 657-665 ◽  
Author(s):  
Juan C. Alonso ◽  
Marina Magaña ◽  
Javier A. Alonso ◽  
Carlos Palacín ◽  
Carlos A. Martín ◽  
...  


1993 ◽  
Vol 50 (10) ◽  
pp. 2100-2105 ◽  
Author(s):  
Miriam Fernandez ◽  
David Armstrong ◽  
Oscar Iribarne

Arrival and settlement of successive cohorts of Dungeness crab, Cancer magister, megalopae were observed in Grays Harbor, Washington, in 1991. The first cohort of megalopae entered the estuary between May 15 and 20 and settled in ("occupied") previously constructed artificial, intertidal oyster shell habitats at densities ranging from 155 to 196 first instar juvenile (J1) crabs∙m−2. Subsequently, a second set of shell habitats was constructed that did not contain crabs of the first cohort ("unoccupied"). Between June 15 and 18, when crabs of the first cohort were a mix of second and third instars, a second cohort of megalopae settled in both occupied and unoccupied shell habitat at respective J1 crab densities of 9–37 and 168–298 crabs∙m−2. The possible roles of cannibalism, competition, and conspecific avoidance are proposed as alternative hypotheses to explain significantly lower density of the second cohort in shell habitats previously occupied by larger conspecifics of the first cohort. Based on laboratory experiments, we suggest that cannibalism is a plausible explanation of our field observations.



1966 ◽  
Vol 23 (9) ◽  
pp. 1319-1323 ◽  
Author(s):  
C. Dale Snow ◽  
John R. Neilsen

A male and female Dungeness crab (Cancer magister Dana) were kept under continuous observation in an aquarium to observe the premating embrace, female ecdysis, and mating. The male held the female in premating embrace from June 10 until June 18, 1965, when she molted. The male allowed the female to reverse her position from the premating embrace, sternum to sternum, to that of female carapace to male sternum only after she became aggressive. The male never allowed the female to escape from his control while she molted. Copulation occurred 1 hr and 32 min after female ecdysis, when the new exoskeleton had firmed somewhat, and the male carried the female in a postmating embrace for 2 days.Extensive wear on the chelipeds of male crabs may reflect prolonged periods in the premating embrace and stroking of the female by the male rather than matings with several females. The male crab probably becomes aware of the female's readiness to molt by her aggressive pinching of maxillae and eyestalks.



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