TY - JOUR
T1 - Drinking and water permeability in the Pacific hagfish, Eptatretus stoutii
AU - Glover, Chris N.
AU - Wood, Chris M.
AU - Goss, Greg G.
N1 - Publisher Copyright:
© 2017, Springer-Verlag Berlin Heidelberg.
PY - 2017/12/1
Y1 - 2017/12/1
N2 - Hagfish are osmoconformers, maintaining an internal osmolality that matches their seawater habitats. Hagfish would, therefore, appear to have no physiological need to drink, but previous studies are equivocal regarding whether drinking in hagfish occurs. The current study addressed this knowledge gap, by examining drinking and water permeability in the Pacific hagfish, Eptatretus stoutii. One-third of analysed hagfish were shown to accumulate radiolabelled drinking rate markers (tritiated inulin and polyethylene glycol-4000) in their gut tissues; however, this was attributed to the presence of markers in the blood perfusing the digestive tract, following absorption through paracellular pathways at the gill. No accumulation of marker was observed in hagfish subjected to more dilute (75% seawater) or more concentrated (125% seawater) media. Diffusive water efflux, measured by tritiated water washout, was shown to be very high, with 50% of body water exchanged within 14 to 16 min, depending on exposure salinity. In full-strength seawater, the total exchangeable pool of water was 78% of hagfish mass. We conclude that hagfish do not drink, and their high water permeability is likely to result in rapid osmotic equilibration under circumstances where perturbations may occur.
AB - Hagfish are osmoconformers, maintaining an internal osmolality that matches their seawater habitats. Hagfish would, therefore, appear to have no physiological need to drink, but previous studies are equivocal regarding whether drinking in hagfish occurs. The current study addressed this knowledge gap, by examining drinking and water permeability in the Pacific hagfish, Eptatretus stoutii. One-third of analysed hagfish were shown to accumulate radiolabelled drinking rate markers (tritiated inulin and polyethylene glycol-4000) in their gut tissues; however, this was attributed to the presence of markers in the blood perfusing the digestive tract, following absorption through paracellular pathways at the gill. No accumulation of marker was observed in hagfish subjected to more dilute (75% seawater) or more concentrated (125% seawater) media. Diffusive water efflux, measured by tritiated water washout, was shown to be very high, with 50% of body water exchanged within 14 to 16 min, depending on exposure salinity. In full-strength seawater, the total exchangeable pool of water was 78% of hagfish mass. We conclude that hagfish do not drink, and their high water permeability is likely to result in rapid osmotic equilibration under circumstances where perturbations may occur.
KW - Drinking
KW - Hagfish
KW - Osmoconforming
KW - Salinity
KW - Water permeability
UR - http://www.scopus.com/inward/record.url?scp=85017475088&partnerID=8YFLogxK
U2 - 10.1007/s00360-017-1097-2
DO - 10.1007/s00360-017-1097-2
M3 - Journal Article
C2 - 28401294
AN - SCOPUS:85017475088
SN - 0174-1578
VL - 187
SP - 1127
EP - 1135
JO - Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology
JF - Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology
IS - 8
ER -