INVESTIGADORES
HALPERIN Julia
artículos
Título:
Bimodal breathing in the estuarine crab Chasmagnathus granulatus Dana 1851--physiological and morphological studies
Autor/es:
HALPERIN J, ANSALDO M, PELLERANO GN, LUQUET CM
Revista:
COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY A-MOLECULAR AND INTEGRATIVE PHYSIOLOGY
Editorial:
ELSEVIER SCIENCE INC
Referencias:
Año: 2000 vol. 126 p. 341 - 349
ISSN:
1095-6433
Resumen:
Chasmagnathus granulatus is an estuarine crab which actively moves from
subtidal to supratidal areas. To elucidate the possible existence of
extrabranchial sites for aerial gas exchange, we measured respiratory
and acid-base variables in animals with and without branchial water
(controls and experimental crabs, respectively) during air exposure. An
histological study of the branchiostegite was also performed.
Throughout 4 h of emergence C. granulatus did not suffer venous
hypoxia, even without branchial water. The rate of oxygen uptake
(M(O(2))) was similar in both groups. The rate of carbon dioxide
excretion (M(CO(2))) and the gas exchange ratio (R) significantly
decreased during emergence in both groups, with R significantly lower
for experimental crabs. Consequently, CO(2) was accumulated in the
hemolymph. This variable stabilized after 90 min in control animals,
but experimental crabs continued accumulating CO(2). Histological study
of the branchiostegites demonstrated the presence of an attenuated and
greatly perfused epithelium facing the branchial chamber lumen, with a
shortest diffusion distance of 0.5 microm. Simple folds and lobulated
projections increase the respiratory surface area. These results
suggest that C. granulatus is a bimodal breathing crab, active both in
water and air. When emerged, this species extract oxygen directly from
air through branchiostegal lungs, but relies on branchial exchange to
eliminate carbon dioxide.