When held in air for up to 24 h, crayfish accumulated Ca(2+) and Mg(2+) in their haemolymph in direct proportion to raised levels of lactate. K(+) levels were highly variable, with elevated levels associated with morbidity. Lactate accumulation in the haemolymph was reflected in proportional increases in lactate levels in the carapace and muscle. Pieces of carapace incubated in saline containing elevated levels of lactate accumulated lactate to up to half the dissolved concentration. Measured levels in the carapace, relative to its water content, implied that lactate accumulated in the carapace in a combined form, possibly complexed to calcium. The exoskeleton seems to provide a reserve of buffering capacity and a sink for lactate during anaerobic metabolism. A similar mechanism has been identified in pond turtles.

Cameron
J. N.
,
Wood
C. M.
(
1985
).
Apparent H+excretion and CO2dynamics accompanying carapace mineralisation in the blue crab (Callinectessapidus) following moulting.
J. Exp. Biol
114
,
181
–.
de Fur
P. L.
,
Wilkes
P. R.
,
McMahon
B. R.
(
1980
).
Non-equilibrium acid—base status in Cancer productus: role of exoskeletal carbonate buffers.
Respir. Physiol
42
,
247
–.
Jackson
D. C.
(
1997
).
Lactate accumulation in the shell of the turtle Chrysemys picta bellii during anoxia at 3degC and 10degC.
J. Exp. Biol
200
,
2295
–.
Jackson
D. C.
,
Goldberger
Z.
,
Visuri
S.
,
Armstrong
R. N.
(
1999
).
Ionic exchanges of turtle shell in vitro and their relevance to shell function in the anoxic turtle.
J. Exp. Biol
202
,
513
–.
Jackson
D. C.
,
Heisler
N.
(
1982
).
Plasma ion balance of946submerged anoxic turtles at 3degC: the role of calcium lactate formation.
Respir. Physiol
49
,
159
–.
Morris
S.
,
Tyler-Jones
R.
,
Bridges
C. R.
,
Taylor
E. W.
(
1986
).
The regulation of haemocyanin oxygen affinity during emersion of the crayfish, Austropotamobius pallipes. II. An investigation of in vivo changes in oxygen affinity.
J. Exp. Biol
121
,
327
–.
Taylor
E. W.
,
Innes
A. J.
(
1988
).
A functional analysis of the shift from gill to lung breathing during the evolution of land crabs (Crustacea, Decapoda).
Biol. J. Linn. Soc
34
,
229
–.
Taylor
E. W.
,
Tyler-Jones
R.
,
Wheatly
M. G.
(
1987
).
The effects of aerial exposure on water balance and the distribution of body water in the freshwater crayfish, Austropotamobius pallipes (Lereboullet).
J. Exp. Biol
128
,
307
–.
Taylor
E. W.
,
Wheatly
M. G.
(
1980
).
Ventilation, heart rate and respiratory gas exchange in the crayfish, Austropotamobius pallipes (Lereboullet) submerged in normoxic water and following 3h exposure in air at 15degC.
J. Comp. Physiol
138
,
67
–.
Taylor
E. W.
,
Wheatly
M. G.
(
1981
).
The effect of long-term aerial exposure on heart rate, ventilation, respiratory gas exchange and acid—base status in the crayfish, Austropotamobius pallipes.
J. Exp. Biol
92
,
109
–.
Truchot
J.-P.
(
1975
).
Blood acid—base changes during experimental emersion and reimmersion of the intertidal crab, Carcinus maenas (L.).
Respir. Physiol
23
,
351
–.
Truchot
J.-P.
(
1980
).
Lactate increases the oxygen affinity of crab haemocyanin.
J. Exp. Zool
214
,
205
–.
Tyler-Jones
R.
,
Taylor
E. W.
(
1988
).
Analysis of haemolymph and muscle acid—base status during aerial exposure in the crayfish, Austropotamobius pallipes.
J. Exp. Biol
134
,
409
–.
This content is only available via PDF.