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Vol. 51 No. 5, 2012
A Shift to an Ion Regulatory Role by Gills of a Semi-Terrestrial Crab, Ocypode stimpsoni
Jyuan-Ru Tsai1 and Hui-Chen Lin1,2,*
1Department of Life Science, Tunghai University, Taichung 407, Taiwan
2Center for Tropical Ecology and Biodiversity, Tunghai University, Taichung 407, Taiwan
Jyuan-Ru Tsai and Hui-Chen Lin (2012)
Ocypode stimpsoni is a highly terrestrial species of the Ocypodidae
that faces challenges of both gas exchange and hypotonic stress when on
land. The aim of this study was to investigate the impacts of
terrestrial modifications on the ion regulatory mechanism of the gills
in this semi-terrestrial crab. Our results showed that the lungs
were the air-breathing organ and may take the place of anterior gills
for gas exchange. Epithelial cells in the anterior gills changed
from a thin epithelium for gas exchange to an intermediate type
epithelium for ion regulation. We also found significantly higher
Na+, K+-ATPase activity in the anterior gills when crabs were
transferred to 3‰ and 5‰ diluted seawater. The ion regulatory
proteins in both the anterior and posterior gills showed similar
localization, an indication of the involvement of the anterior gills in
ion regulation. Cell thicknesses and Na+, K+-ATPase activity
suggest that the anterior gills can assist with ion regulation in
acclimation to dilute seawater. We concluded that the presence of
the lungs caused the gills to be modified for ion regulation.
Key words: Air-breathing organ, Terrestrial adaptation, Lung, Ion regulation, Ocypode stimpsoni.
*Correspondence: Tel and Fax: 886-4-23500461. E-mail:hclin@thu.edu.tw
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