Molt Cycle of Male Snow Crabs, Chionoecetes Opilio, from Observations of External Features, Setal Changes, and Feeding Behavior

1988 ◽  
Vol 8 (2) ◽  
pp. 164-176 ◽  
Author(s):  
M. J. O’Halloran ◽  
R. K. O’Dor
Keyword(s):  
Feeding Behavior ◽  
Molt Cycle ◽  
Chionoecetes Opilio ◽  
Snow Crabs

Growth and moulting of wild-born immature snow crabs, Chionoecetes opilio (Fabricius, 1788) (Decapoda, Majoidea), in the laboratory

Crustaceana ◽  
2015 ◽  
Vol 88 (7-8) ◽  
pp. 911-922 ◽  
Author(s):  
Takeo Yamamoto ◽  
Tatsuya Yamada ◽  
Takahiro Kinoshita ◽  
Yuji Ueda ◽  
Hiroshi Fujimoto ◽  
...  
Keyword(s):  
Sea Of Japan ◽  
Probability Model ◽  
Natural Habitat ◽  
Carapace Width ◽  
Laboratory Culture ◽  
The Sea Of Japan ◽  
Growth Indices ◽  
Chionoecetes Opilio ◽  
Model Based ◽  
Snow Crabs

Growth and moulting of wild-born immature snow crabs (Chionoecetes opilio (Fabricius, 1788)) were investigated by laboratory culture experiments. Crabs with 16.2-42.9 mm carapace width caught from the Sea of Japan were cultured at a temperature of their natural habitat (approximately 1°C). The growth indices (size increments at moulting in mm and in % of premoult carapace width) and intermoult period were significantly affected by premoult carapace width, but sex did not affect these variables. Furthermore, we demonstrated that premoult carapace width and days after moulting significantly affected moulting probability and we developed a moulting probability model based on these variables. From this model, the number of days of intermoult periods when moults occurred in 50% of crabs of instars VI, VII and VIII was estimated at 234, 284 and 346 days, respectively.

scholarly journals Effects of temperature on growth of juvenile snow crabs, Chionoecetes opilio, in the laboratory

2015 ◽  
Vol 35 (2) ◽  
pp. 140-148 ◽  
Author(s):  
Takeo Yamamoto ◽  
Yuji Ueda ◽  
Hiroshi Fujimoto ◽  
Tatsuya Yamada ◽  
Takahiro Kinoshita ◽  
...  
Keyword(s):  
Chionoecetes Opilio ◽  
Effects Of Temperature ◽  
Snow Crabs

Functional Maturity in Small Male Snow Crabs (Chionoecetes opilio)

1988 ◽  
Vol 45 (12) ◽  
pp. 2106-2109 ◽  
Author(s):  
G. P. Ennis ◽  
R. G. Hooper ◽  
D. M. Taylor
Keyword(s):  
Rapid Development ◽  
Carapace Width ◽  
Reproductive Potential ◽  
Snow Crab ◽  
Small Male ◽  
Chionoecetes Opilio ◽  
In Captivity ◽  
Breeding Migration ◽  
High Level ◽  
Snow Crabs

The mean size of male snow crabs (Chionoecetes opilio) in sexual pairs during the annual spring breeding migration to shallow water in Bonne Bay, Newfoundland, decreased from 118.6 mm carapace width (CW) in 1983 to 100.3 mm in 1987. This decrease is due to an increase in males <95 mm CW participating from 1.5% in 1983 to 32.3% in 1987. This change appears to have resulted from a reduced abundance of commercial size [Formula: see text] males due to a rapid development of an illegal fishery on this previously unfished population and, as a consequence, less competition between males for possession of females. The percentages of spermathecae containing new spermatophores for females paired with males <95 mm CW (67%) and those with males [Formula: see text] (79%) were not significantly different. We assumed that each female with new spermatophores had recently mated with the male with which it was paired. Observations on selected pairs in captivity showed that males <95 mm CW are capable of mating with both primiparous and muitiparous females. Our results indicate that small mature males can replace large males in breeding activity in a snow crab population. We conclude that in the male-only snow crab fishery in Atlantic Canada with a minimum legal size of 95 mm CW, population reproductive potential is maintained at a high level despite high exploitation rates on males [Formula: see text].

Population Structure of Alien Snow Crabs (Chionoecetes opilio) in the Kara Sea (Trawl and Video Sampling)

Oceanology ◽  
2020 ◽  
Vol 60 (1) ◽  
pp. 83-88
Author(s):  
A. K. Zalota ◽  
V. A. Spiridonov ◽  
S. Galkin ◽  
A. A. Pronin
Keyword(s):  
Population Structure ◽  
Kara Sea ◽  
Chionoecetes Opilio ◽  
Snow Crabs

Neuromuscular analysis of the chela-closer muscle associated with precopulatory clasping in male snow crabs, Chionoecetes opilio

1992 ◽  
Vol 70 (12) ◽  
pp. 2356-2363 ◽  
Author(s):  
C. K. Govind ◽  
A. T. Read ◽  
W. T. Claxton ◽  
R. W. Elner
Keyword(s):  
Carapace Width ◽  
Motor Pattern ◽  
Low Frequency ◽  
Thick Filament ◽  
Thin Filaments ◽  
Chionoecetes Opilio ◽  
Sustained Activity ◽  
Synaptic Potentials ◽  
Slow Fiber ◽  
Snow Crabs

Male snow crabs, Chionoecetes opilio (Majidae), use their modified chelae to retain females for weeks before copulation. Consequently, adaptations for such sustained activity were examined in the chela-closer muscle responsible for clasping. Based on an allometric increase in the ratio of chela size to carapace width, male snow crabs were categorized as morphometrically mature or immature, the former displaying precopulatory clasping more readily than the latter. However, the two types were similar in terms of the properties of the chela-closer muscle, which was examined in this study. The motor pattern during clasping consisted of low-frequency firing of one of the excitor motoneurons, which gives rise to small synaptic potentials. The other excitor motoneuron, which produces large synaptic potentials, fired only when the female struggled during the embrace. The synaptic potentials of both axons showed little if any fatigue at these low firing frequencies. The neuromuscular terminals of these motoneurons displayed areas of synaptic contact larger than most found in other tonically active crustacean muscles. The majority of these synapses had an active site for transmitter release denoted by a dense bar, with many containing more than three dense bars. The closer muscle had typically slow features, with 10 or 11 thin filaments surrounding a thick filament, and sarcomere lengths of 9 – 10 μm. Overall, the closer muscle with its slow-fiber composition, tonic motoneurons, and neuromuscular synapses is well suited to sustained, low-level activity such as precopulatory clasping.

Ejaculate-storage patterns and the site of fertilization in female snow crabs (Chionoecetes opilio; Brachyura, Majidae)

2000 ◽  
Vol 78 (11) ◽  
pp. 1902-1917 ◽  
Author(s):  
Guy Sainte-Marie ◽  
Bernard Sainte-Marie ◽  
Jean-Marie Sévigny
Keyword(s):  
Microscopy Study ◽  
Sperm Precedence ◽  
Single Male ◽  
Chionoecetes Opilio ◽  
Intermediate Chamber ◽  
Snow Crabs ◽  
Multiple Male ◽  
Storage Patterns ◽  
Basic Configuration ◽  
Amorphous Matter

A light-microscopy study of mated female snow crabs (Chionoecetes opilio) was conducted to investigate the site of fertilization and to resolve how multiple ejaculates are stored in the spermathecae. In its basic configuration, an ejaculate consisted of a layer or patch of spermatophores enclosing mature spermatids that was capped by a relatively large volume of amorphous matter, which in turn could include a patch of spermatophores containing immature spermatids. Up to 10-12 ejaculates were stored in the spermathecae with the largest loads. An ejaculate was initially deposited in the intermediate chamber and ventral part of the spermatheca, and was displaced toward the dorsal part of the spermatheca when a new ejaculate was inserted. Ejaculates were neatly stratified along the ventrodorsal axis of spermathecae with small to moderate loads, but they were disrupted and the storage pattern was disorderly in spermathecae with large loads. Ejaculate stratification favors last-male sperm precedence and single-male paternity. However, multiple-male paternity might occur in females with large spermathecal loads, in part because several ejaculates can co-occur close to the oviduct opening. Mixing of male and female gametes in preparation for oviposition, and probably also fertilization, occurs to some degree in the ovaries.

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