CHENG, A.*; MERZ, R.A.; Swarthmore College; Swarthmore College: Solutions to staying put: Two sticky scyphozoans

Although most scyphozoans are pelagic, a few such as Cassiopea and Haliclystus have become benthic. Cassiopea live their medusoid lives resting on coral or sandy bottoms, pulsating upside-down in shallow waters, exposing zooxanthellae within their oral arms to light. Haliclystus is found adhering to subtidal marine algae and grasses exposed to the swash within surge channels. This attached lifestyle requires that these jellyfish possess unique physical and behavioral characteristics that differ from their pelagic counterparts. We hypothesized that the densities of both Cassiopea and Haliclystus were greater than seawater or pelagic jellyfish. Jellyfish density was measured by exposing the animals to increasing seawater concentrations to determine the point at which they were neutrally buoyant. The densities of Cassiopea (1.032 g/mL) and H. auricula (1.032 g/ml) were found to be greater than the seawater to which they were exposed (1.025 g/ml). Cassiopea xamachana and frondosa were observed at varying flow velocities on both sand and plexiglass substrata in a flow tank. Pulsation rate did not to vary with water velocity, thus it does not appear that the rate of contraction of the bell helps the animals remain in place on a substrate. However, the aboral surface does secrete mucus, which can �glue� the jellyfish onto a smooth substratum or bind it to sand, effectively weighing down the jellyfish. The ability of H. auricula to attach and remain attached to marine flora was assessed. Transects through algal beds at Cattle Point on San Juan Island, WA revealed that H. auricula was found on ten species of red and green algae and grasses, but never on kelps. In the lab, it was determined that this pattern of distribution was not due to the preference of H. auricula, but rather to the adhesive characteristics of the algal blade.