The Doliolid, Doliolum nationalis : 2012

Photograph by

Richard Kirby

About this image

Light micrograph of the adult doliolid Doliolum nationalis. The larval stage of this creature possesses a notochord – a flexible rod-like structure of supporting cells – and so, like humans, they belong to the phylum Chordata. This 1.5 mm long, adult doliolid possesses bands of muscle around its barrel-shaped body that help it swim and feed as it drifts among the plankton at the sea surface. Contraction and relaxation of the muscles draws water in through the buccal siphon (right) and over the comb-like gills before it is expelled as a jet from the atrial siphon (left). A mucus sheet situated behind the gills traps food particles before the stream of water leaves the animal’s body. University of Plymouth, Marine Institute, Plymouth, United Kingdom