Fig 1.
Schematic diagram of the anatomy of the crab Cancer pagurus L.
A, External anatomy and numbering of legs. B, Arrangement of the nervous system. C, Leg anatomy and muscles. D, Leg sense organs stimulated in the current study.
Fig 2.
(A) Recording from the nerve of an isolated C. pagurus leg. (B) Stimulating the crab leg nerve while recording the forces produced by the dactylopodite closer muscle.
Fig 3.
Recordings from the central nervous system in intact crab.
Nerve activity recorded extracellularly in the left circumoesophageql connective of an intact C. pagurus crab. A, Spontaneous activity; B, Responses to touching eyestalks and a burst associated with fictive locomotion; C, Responses to vibration. Scale bars 2.5 s.
Fig 4.
Recording CNS activity before and after electrical stunning.
Spontaneous nerve activity recorded extracellularly in the left and right circumoesophageal connectives of C. pagurus after cutting at the level indicated. A,B: intact animals; C,D: 10 min after electrical stunning. Scale bar 1s.
Fig 5.
Time course of CNS activity with and without electrical stunning.
Spontaneous nerve activity recorded extracellularly in the left circumoesophageal connective of C. pagurus. A: activity in intact animal initially and after 60 min; B: activity in another crab at 10 min and 60 min after electrical stunning. Scale bar 1s.
Fig 6.
Recording sensory activity before and after electrical stunning.
Responses of the leg nerve of C. pagurus preparation to three forms of stimulation of the dactylopodite (A-C) as indicated. Top panels, leg R2 autotomised from intact animal before stunning; lower panels, leg L2 amputated from same animal after electrical stunning. Scale bar 5 s.
Fig 7.
Time course of sensory activity with and without electrical stunning.
Responses of sensory neurones in the leg nerve of the crab C. pagurus to three forms of stimulation of the dactylopodite (A-C) as indicated, measured at 10 min and 60 min after leg isolation. Top panels, leg L1 autotomised from intact animal; lower two panels, leg L2 amputated from the same animal after electrical stunning. Scale bar 5 s.
Fig 8.
Recording motor output before and after electrical stunning.
Forces produced by the dactylopodite closer muscle of the leg of C. pagurus in response to stimulation of motor neurones in the leg nerve at various frequencies. A: leg R2 autotomised from intact crab; B: leg L2 amputated from the same crab after electrical stunning, measured at 10 min and 60 min post-stun. Stimulus voltage 4V.
Fig 9.
Measures of physiological stress before and after electrical stunning.
Haemolymph L-lactate concentrations in C. pagurus before and after electrical stunning (black bars) or a sham-treatment (white bars). Mean values ± SEM. N = 6 for each treatment group. (*) indicates that values are significantly different (p<0.05), (NS) indicates values are not significantly different, (Δ) indicates the difference/increase following the two treatments considering the changes in the values for individual crabs; (t-test p<0.05).
Table 1.
Haemolymph L-lactate concentrations measured in decapod crustaceans in response to various stressors.