Meeting Abstract
The Cirolanidae are marine isopods, with some species found in karstic habitats. Several specimens of a Cirolana species were recently discovered in southwestern Madagascar in a subterranean freshwater cave, when they were found feeding on humans that entered the water. These specimens were determined to be C. poissoni. The original type specimens of the species, found in the nearby Mitoho cave in 1948 and originally deposited in the Museum National d’Histoire Naturelle in Paris, are apparently lost; therefore the present specimens comprise the only extant collection. Very little is known about the biology of the Cirolanidae, and in this study we present notes on the ecology and feeding behavior of C. poissoni for the first time. In brief, our findings suggest that C. poissoni exhibits active swimming behavior in open waters, with increased activity in low light conditions, and exhibits predatory or scavenging feeding habits, but not cannibalism. One specimen was fed on a volunteer and the feeding process, which occurred for 16 continuous minutes, was documented. Following the feeding bout, the isopod grew from 8.2 mm to 11.4 mm, about 1 mm every ten days, during the study. Other specimens that had a visible blood meal at the time of collection survived for 40 days without any supplementation. Finally, in the cave, alongside these isopods is the largest fossil site in all of Madagascar, containing pristine specimens of extinct Malagasy species (including the giant lemurs) that the scavenging C. poissoni may have fed on historically. Blood meal analyses from collected specimens will reveal what other cryptic organisms are currently living in this underwater cave, and the dietary preferences of C. poissoni.
