Meeting Abstract

26.5  Monday, Jan. 4  Form, function, and evolution of holotrichous isorhiza nematocysts REFT, A.J.; Ohio State Univ. reft.1@osu.edu

Although Cnidaria consists of a diversity of body forms and life cycles, all members produce nematocysts, which provides the phylum with a strong synapomorphy. Understanding the evolution of nematocysts, intracellular capsules important for the capture of prey, defense against predators, and intraspecific aggression, is an important component of understanding the morphological evolution of cnidarians. Although nematocysts display a high degree of morphological variation (with over thirty identified types), most hypotheses of the sequence of evolution of nematocysts have focused on the holotrichous isorhiza (holotrich), the simplest morphology of spine-bearing nematocyst. However, there have been few studies quantitatively evaluating these hypotheses of evolution. To begin to address various ideas of nematocyst evolution, I used various forms of microscopy to study the form and function of holotrichs across the phylum to identify how this nematocyst type varies within Cnidaria. I find that the category holotrich consists of a higher degree of variation than previously speculated and I can begin to evaluate suggested scenarios of nematocyst evolution.