Meeting Abstract

25.7  Monday, Jan. 5  Stable isotope analysis: a quantitative approach to linking diet and morphological specialization in mantis shrimp DEVRIES, M.S.; Univ. of California, Berkeley msdevries@berkeley.edu

Many animals have specialized feeding structures used to consume specific prey types. Mantis shrimp provide an excellent system to study the relationship between morphological and diet specialization, because their raptorial appendages capture a wide range of prey items and exhibit tremendous morphological diversity. Currently, knowledge of mantis shrimp morphology far exceeds that of diet. Stable isotope analysis (SIA) has made it possible to quantify diet specialization across mantis shrimp taxa. Specifically, stable isotope mixing models determine the percentage of prey types in a predators diet in order to estimate diet specialization with a standard diversity index that applies to any taxonomic group. One potential difficulty with SIA is the variation in stable isotope composition among habitats. My goal was to determine the effects of habitat variation on isotopic analyses of diet in Neogonodactylus bredini, a species with hammer-like appendages thought to be specialized for smashing hard-shelled prey. Animals were collected from seagrass and rock habitats along with potential prey items (clams, crabs, hermit crabs, fish, and snails). Mixing model analyses of diet were then run on each group of animals from the two habitats. The mixing model analysis of N. bredini from the rock habitat revealed mean (SD) percentages of 652% fish, 138% clams, 128% crabs, 54% hermit crabs, and 43% snails, while the analysis of N. bredini from seagrass failed to converge on a plausible solution. These analyses suggest that N. bredini feeds primarily in the rock habitat where it consumes both hard- and soft-bodied prey. Thus, while N. bredini appears to be specialized for breaking hard-shelled prey, it actually consumes a wider diversity of prey than what is currently documented in the literature.