These 2nd, 3rd and 4th instar larvae and the pupa were photographed through the wall of an aquarium. The pharate adult is clearly visible. It is almost ready to emerge, having already undergone pneumatization, where it has replaced the fluid between it and the pupal wall with air. 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. .
