Crinoids are passive suspension feeding organisms capturing food particles out of the water with finger like podia covering their arms. The arms, differing in number and division pattern, create a three dimensional filter. Crinoids are known since the Palaeozoic, when stalked forms were very abundant in the oceans and showed a great variation in morphology. In this project different filtering morphologies from extinct and extant stalked crinoids are compared. Filter feeding mechanisms, efficiency and fluid mechanical attributes are determined using the program package CFX of the ANSYS® Academic Research, Release 12.1. Flow channel experiments (Particle Image Velocimetry) will also be performed using synthetic models of crinoids.
Filter feeding in the Triassic crinoid Encrinus liliiformis (Dynowski et al . 2016)
Encrinus liliiformis: Flow results for the base model and aboral inflow at Vinit = 0.14 m/s. (A) Overview illustrating model orientation and individual velocity components. (B) Combined contour-vector plot illustrating recirculation on ZX plane in oblique view. (C) Combined contour-vector plot illustrating recirculation on XY plane in oblique view. (D) Combined contour-vector plot illustrating recirculation on ZX plane in top view. (E) Linegraph plot of velocity component u directly behind the end of the arms (location indicated by dotted line in (D). Negative u values indicate recirculation zone. (Dynowski et al . 2016)
Dynowski, J.F., Nebelsick, J.H., Klein, A., & Roth-Nebelsick, A. (2016): Computational Fluid Dynamics Analysis of the Fossil Crinoid Encrinus liliiformis (Echinodermata: Crinoidea). PLoS ONE. doi: 10.1371/journal.pone.0156408