Graduation Year


Document Type




Degree Name

Master of Science (M.S.)

Degree Granting Department

Biology (Integrative Biology)

Major Professor

Thomas Crisman, Ph.D.

Committee Member

Jason Rohr, Ph.D.

Committee Member

Mark Rains, Ph.D.

Committee Member

David Lewis, Ph.D.


behavior, fouling, grooming, Macrobrachium, shrimps, setae


The giant freshwater shrimp, Macrobrachium rosenbergii is a large species of prawn grown extensively in aquaculture settings. A social hierarchy exists within the males of this species, representing three distinct male morphotypes. These male morphotypes differ in their behavior, physiology, and morphology and include the largest blue-clawed males (BC males), moderately- sized orange-clawed males (OC males), and the undifferentiated small-clawed males (SM males). All individuals of this species perform grooming behaviors to rid themselves of body fouling which can impede important functions such as movement, respiration, chemoreception, and reproduction. Grooming behaviors in crustaceans often utilize specialized structures called setae, which aid in the removal of fouling material such as debris, algae, and epibionts. The grooming behaviors of M. rosenbergii were examined in this thesis to better understand the importance of these behaviors.

Grooming behaviors were commonly seen among all sexes and morphotypes of M. rosenbergii along with other behaviors such as searching for food/habitat, reproductive attempts, and agonistic interactions (N=94). As a species, there were no differences in the regions of the body groomed in terms of frequency and duration. In general, the most commonly used grooming appendage, the first pereopods, and the antennae were most frequently groomed. The antennae are an important site of chemosensory reception and were likely frequently groomed to maintain this sensory input. The internal sites for respiration, the gills, were groomed for the longest amount of time, indicating the importance of removing fouling from these structures. Of the females and male morphotypes, the largest and most dominant BC males performed the most grooming actions and spent the most time grooming, compared to other individuals within the species. This high grooming time budget (35%) is likely due to their position within the social hierarchy; these males must maintain their body along with the structures which allow them to maintain their dominance such as large chelipeds used in territorial interactions with other males.

Grooming behaviors in crustaceans were previously hypothesized as secondary behaviors, only occurring when other behaviors were not prioritized. Results from this study provide further evidence of this hypothesis; although grooming is considered an important behavior to remove fouling and prevent interruptions in functions such as respiration, locomotion, and reproduction, it’s frequency and duration decreases when other behaviors prove more beneficial.

Results from this thesis continue to validate the adaptive value of grooming in the changing environmental conditions crustaceans experience on a daily basis. These behaviors remove fouling from the body and promote locomotion, respiration, chemoreception, and reproduction. In addition, shrimps grown in aquaculture settings may experience increased fouling when in grow-out ponds. This increased exposure to fouling organisms and debris may lead to an increased mortality of profitable shrimps. Understanding the fouling pressures and grooming abilities of these shrimps during vulnerable times such as placement in grow-out ponds and intermolt periods may increase yield and profitability for aquaculture farmers.