To Swim, or Not To Swim, That Is the Question: An Ancestral State Reconstruction Based on Benthic Behaviors Across Medusozoa

Medusozoa is one of the major clades within the phylum Cnidaria. The Cnidarian phylogeny strongly suggests that the swimming medusa (jellyfish) stage has evolved one or more times within Medusozoa. A free-swimming medusa could impact the biology of a lineage in several ways such as introducing access to new food sources in the water column, increasing dispersal ability, and increasing species ranges. Medusae are generally viewed as pelagic animals; however, some Medusozoa species prefer the ocean floor. These jellies are said to be benthic/benthopelagic. Not much is known about the benthic or benthopelagic behaviors among Medusozoans. The goal of this research was to solve a bit of that puzzle by investigating the origins of the benthic/benthopelagic behavior displayed by come Medusozoa species. In order to do this, a list of all Medusozoan species and genera was compiled and coded for the expression of benthic/benthopelagic behaviors. This information was then applied to an existing phylogenetic tree, and an ancestral state reconstruction was performed using R. The results indicated that benthic/benthopelagic behaviors independently evolved at least 6 times across Medusozoa.