Meeting Abstract
The sessile lifestyle is a derived condition within Rotifera. This rare lifestyle is found in approximately 100 species within the Superorder Gnesiotrocha. Sessile rotifers tend to be larviparous, possessing short-term free-swimming larvae that are morphologically and ecologically distinct from the sessile adult. To date, there is limited information about gnesiotrochan larvae or the process of metamorphosis that gives rise to the adult body plan. Here, I use a combination of light microscopy, f-actin staining, confocal laser scanning microscopy, and digital video to capture the metamorphic process in two species of Stephanoceros and document both the development of the adult head (aka infundibulum) and associated changes in muscle patterns as the larva undergoes drastic metamorphosis. Results indicate that larvae have a relatively simple orthogonal grid of band-like muscles, and that this grid-like network changes during the precocious development of the infundibulum. This development appears to involve changes in the larval foregut, where the adult head presumably arises from, and leads to the production of five tentacles that each contains their own orthogonal grid of muscles. Contraction of circular muscles in the larval body appears to be responsible for the emergence of the infundibulum through the larval mouth. The adaptive nature of this drastic metamorphic process is explained in the context of the sessile lifestyle.
