Abstract
Body morphologies are significantly different amongst the members of the Drusinae subfamily. Aligned with such differences is the
selective niche location chosen by many species from the subfamily. Typically, they live on the sediments of cold, well-oxygenated
mountain streams from the Eurasian Region. However, each of the three evolutionary lineages (shredders, grazers and carnivorous
filter feeders) inhabit different hydraulic locations according to their foraging behaviour. To investigate the relationship between the
body morphology and the flow field near the body, we use Large Eddy Simulations to compute the flow past five different species of
the subfamily. We selected species representing the three evolutionary lineages of the subfamily, Drusus alpinus Meyer-Dür 1875
from the shredders clade, D. bosnicus Klapálek 1899 and D. monticola McLachlan 1876 from the grazers clade and Cryptothrix
nebulicola McLachlan 1867 and D. discolor (Rambur 1842) from the filter feeders clade. For the simulations, three-dimensional
body shapes were reconstructed from X-ray micro CT data and exposed to a turbulent flow corresponding to water-depth and ve-
locity data measured in the field. The total forces acting on each morphotype were found to be comparable. The lift coefficients
computed and ranging from 0.07 to 0.17 are smaller than the drag coefficients which were found to range from 0.32 to 0.55. The
local distribution of the skin-friction indicates flow-separation zones near the edges of the bodies, in particular, between the head
and the pronotum, which are differently located according to each species. Moreover, we observe higher streamwise normal stresses
upstream of the head of the filter feeder species. It is hypothesised that the upstream horseshoe vortex can lift up drifting food par-
ticles and transport these to the larvae’s filtering legs, thereby enhancing the encounter rates of particles with the filtering devices.
selective niche location chosen by many species from the subfamily. Typically, they live on the sediments of cold, well-oxygenated
mountain streams from the Eurasian Region. However, each of the three evolutionary lineages (shredders, grazers and carnivorous
filter feeders) inhabit different hydraulic locations according to their foraging behaviour. To investigate the relationship between the
body morphology and the flow field near the body, we use Large Eddy Simulations to compute the flow past five different species of
the subfamily. We selected species representing the three evolutionary lineages of the subfamily, Drusus alpinus Meyer-Dür 1875
from the shredders clade, D. bosnicus Klapálek 1899 and D. monticola McLachlan 1876 from the grazers clade and Cryptothrix
nebulicola McLachlan 1867 and D. discolor (Rambur 1842) from the filter feeders clade. For the simulations, three-dimensional
body shapes were reconstructed from X-ray micro CT data and exposed to a turbulent flow corresponding to water-depth and ve-
locity data measured in the field. The total forces acting on each morphotype were found to be comparable. The lift coefficients
computed and ranging from 0.07 to 0.17 are smaller than the drag coefficients which were found to range from 0.32 to 0.55. The
local distribution of the skin-friction indicates flow-separation zones near the edges of the bodies, in particular, between the head
and the pronotum, which are differently located according to each species. Moreover, we observe higher streamwise normal stresses
upstream of the head of the filter feeder species. It is hypothesised that the upstream horseshoe vortex can lift up drifting food par-
ticles and transport these to the larvae’s filtering legs, thereby enhancing the encounter rates of particles with the filtering devices.
| Original language | English |
|---|---|
| Pages (from-to) | 269–278 |
| Journal | Contributions to Entomology |
| Volume | 73 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - 2023 |
Austrian Fields of Science 2012
- 106047 Animal ecology