Gill morphology of the intertidal estuarine crab Chasmagnathus granulata Dana, 1851 (Decapoda, Grapsidae) in relation to habitat and respiratory habits.

LUQUET, C. M.; ROSA, G. A.; FERRARI, C. C.; GENOVESE, G.; PELLERANO, G. N.

CRUSTACEANA

BRILL ACADEMIC PUBLISHERS

Lugar: Leiden; Año: 2000 vol. 73 p. 53 - 67

0011-216X

Histological and morphometric analyses were performed on the gills of the semiterrestrial estuarinecrab Chasmagnathus granulatus. Three different epithelia were recognized: (1) A thinepithelium, 2:42 § 0:33 ·m thick, which lines the whole lamellae in the three anterior gills andwas assigned to respiratory functions. (2) A thick cuboidal epithelium, 6-12.5 ·m thick, coveringpart of gills 4 and 5 and the better part of the three most posterior gills. This tissue seems to beinvolved in ion-regulation, since it is located in the same zones which are darkly stained with silvernitrate and possess large numbers of mitochondria, closely associated to basolateral interdigitationsand abundant infoldings of the apical membrane. (3) An attenuated epithelium, 0.5-1.5 ·m thick,bordering the marginal channels of all the gills. This tissue is clearly of a respiratory type andprobably plays an important role during air breathing when the branchial water stores becomereduced by evaporation, and the consequent gill collapse impairs both ventilation and perfusion ofthe central part of the lamellae.During exposure to humid air, C. granulatus is able to maintain its branchial chambers almostcompletely ® lled with water, thus keeping its gills functional in spite of little mechanical support.These adaptations for maintaining gill respiration in air allow C. granulatus to sustain highmetabolic rates during emergence, with little increase in venous partial pressure of carbon dioxide.