Water flow (large arrow) over the pupa and around the plastronic gills (silver protuberences at top of pupa) causes sufficiently low pressure to produce a bubble of air (B). To see a diagram illustrating the flow patterns around such a pupa.
Other structures labelled are the suckers (S) and trachael gills (T) of the larvae, and the attachment pads (AP) of the pupa.
The water velocity was ca. 80 cm/s and the water depth was ca. 6 cm. The scale bar = 1.0 mm
Picture Copyright © 1995 by Douglas A. Craig. All rights reserved. .