Visualization of the Flow Around Shells Used by Hermit Crabs

Barbara Casillas
G. Alcaraz
R. Ledesma
R. Zenit
Universidad Nacional Autonoma de Mexico

The flow around gastropod shells used by hermit crabs (Calcinus californiensis) was visualized experimentally. These crabs choose their shells according to many factors; it is believed that the choice of shell (shape and weight) is directly related to the drag caused over them by the exposure to wave action .

Using a visualization technique called particle image velocimetry (PIV), we can see what the flow around the shells looks like. From these measurements, we are able to quantify the amount of drag exerted on the shells by the flow. We have found that the drag around rough shells is smaller at large velocities; for smaller velocities, the drag around smooth shells is smaller. These observations are in agreement with field observations (Argüelles et al., Sci. Mar., 2009).

This work is funded by the National Autonomous University of Mexico research program (PAPIIT-UNAM).

References

Argüelles et al., Science, March, 2009

Reporters and Editors

Reporters can freely use these images. Credit: Barbara Casillas Thesis (UNAM), 2009.