Visitor Working on the Beautiful Stalked Jellyfishes

I am visiting the Department of Invertebrate Zoology, under supervision of Dr. Allen G. Collins, for nine months. I study the evolution of class Staurozoa (Cnidaria), also known as stalked jellyfishes. Only about 50 different species in this class are known, but they have fascinating biology and are also quite beautiful. 

I am a PhD candidate from the Laboratório de Evolução Marinha (Laboratory of Marine Evolution), Departamento de Zoologia, Instituto de Biociências, Universidade de São Paulo, Brazil. My visit is being funded by the Brazilian government’s CAPES PDSE program.

Haliclystus antarcticus Pfeffer, 1889 attached to rock or algae. Image courtesy of Dr. André Carrara Morandini.

I am working on an integrative study of the class, encompassing: (1) a broad molecular phylogeny, (2) the taxonomic/evolutionary meaning of their nematocysts, (3) the evolution of the their body plan (internal morphology).

Because of prior work, we know that the taxonomy of Staurozoa needs to be reassessed. Several of the traditional taxa are composed of only distantly related species. I am finding that the stinging cells, or nematocysts, of Staurozoa seem to play a fundamental role in staurozoan evolution. By examining morphometric data of nematocysts, I can uncover some of the evolutionary history of the group.

I am also conducting a comprehensive study of the histological morphology of the group. Using these data and a robust understanding of the relationships of the different staurozoans, I plan to infer the history of body plan evolution of these animals. 

 

Different types of nematocysts found in the tips of tentacles of Haliclystus salpinx Clark, 1863, used for defense and prey capture.

Histology of the anchor (adhesive structure), and its connection with the main body of Haliclystus antarcticus Pfeffer, 1889.

by Lucília Souza Miranda