Thesis (M.S.)--University of Oregon, 2008. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 51-55). Also available online.

ix, 55 p. : ill., maps. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / Aggressive behaviors in many animals increase juvenile survival and reproductive success. I explored the role of aggressive behavior in maternal care and male-male competition in caprellid amphipods. Attacks of females in three reproductive states toward male and female conspecific and congeneric caprellids were quantified. Parental females showed greatest aggression toward males of both species, suggesting these caprellids may pose threats to juveniles. Paired males were exposed to females in three reproductive states and other males and fought most often in the presence of nonbrooding females. This finding suggests that males recognize and fight over receptive females. Males fight with the second gnathopods and "poison tooth," which may cause fatalities in conflicts. Mortality rates of males with and without (removed) poison teeth were not significantly different, but the highest observed mortality rate was no-tooth caprellids when paired with toothed males, suggesting presence of the teeth may impact the outcome of male-male conflicts.

The Caprellidae are a specialized suborder of Amphipoda, which are highly modified for a semisessile life. Caprellids exhibit direct development and brood their young. The suborder is exclusively marine and commonly found on filamentous algae, sea grasses and fouling communities. Most published works on caprellids have been primarily concern~d with systematics (Caine, 1974; Dougherty, 1943; Laubitz, 1970, 1972; McCain, 1968, 1975), although a few recent studies have dealt with ecology and ethology (Bynum, 1978; Caine, 1977; Keith, 1969, 1971; Lewbel, 1978; Saunders, 1966). This study examines·spatial and temporal variations in distribution, abundance and population structure as well as describing intraspecific aggressive behavior of Caprella californica Stimpson. ~- californica is dioecious and has marked sexual dimorphism in both its size and secondary sex characteristics. It is found from San Diego to the South China Sea (Laubitz, 1970), and is the dominant caprellid in the Zostera marina beds of the local bays and is a major diet item for many of the eel grass associated fishes. There is a preponderance of females in the population as well as a size-specific distribution of the proportion of the sexes.