Meeting Abstract

41-4  Friday, Jan. 5 08:45 - 09:00  Deconstructing the mason spider mound: mound building behavior, function, and ecology in spiders RABOIN, M*; ELIAS, D.O.; Univ. Of California, Berkeley; Univ. Of California, Berkeley maggie.raboin@berkeley.edu

Animal builders are littered throughout the known animal kingdom and the structures they construct are highly diverse in form and function. Animals build structures to modify their immediate environment and thus control environmental and ecological factors to increase their fitness. Spiders are well known for their building behavior because many of them construct structures such as elaborate webs for prey capture and excavated burrows for protection. Mason spiders are unique among spiders because they do not construct typical webs or burrows; they build mounds. They construct mounds by stacking pebbles and dried leaves on top of their egg cases and sealing each piece of debris in place with silk. Despite the conspicuous nature of the mason spider’s mound building behavior, the function of these mounds is unknown. We conducted a field experiment to determine if mounds protect mason spider eggs from (1) parasitism by wasps, (2) fluctuating temperatures, or (3) desiccation. During the summer of 2017, we manipulated mounds at four different time intervals following their construction. After some time, we collected and dissected egg cases to determine the rates of parasitism, desiccation, mortality, and stage of development for each egg case. Our results suggest that mounds function in a variety of contexts. We suggest that mounds allow spiders to survive the extreme conditions of their natural habitats.