Lack of gas bladder inflation by the larvae of zebrafish in the absence of an air‐water interface

Abstract

Compared to a control gas bladder inflation rate of 95·1±1·9%, zebrafish Danio rerio larvae 72 h post‐fertilization maintained in closed chambers had an inflation rate of just 19·1±7·7%. Larval survivorship through 10 days in closed chambers (32%) was significantly less than that in open chambers (76%), and the extent of spinal curvature was significantly higher among larvae maintained in closed chambers. Larvae which failed to inflate their gas bladder showed very little change in body length, and had a final dry weight c. 14% of that for control larvae. The small number of larvae with inflated gas bladders found in closed chambers might be attributed to the inadvertent introduction of small bubbles into two replicates. These results indicate that access to an air‐water interface is critical for the normal development of zebrafish larvae, but also that a small, submerged, spherical gas volume may to a limited extent be used for initial gas bladder inflation.