Figure 1: Filtration models in suspension-feeding fishes.
From: Fish mouths as engineering structures for vortical cross-step filtration
(a) Current model of crossflow filtration. Mainstream flow travels tangentially across the branchial arches and concentrates particles in the posterior oral cavity1. Filtrate exits between gill rakers and passes the gill filaments where gas exchange occurs. (b) Paddlefish with gill rakers forming the porous floor of deep slots between branchial arches. (c) Convergent morphology in the basking shark. (d) Vortical cross-step filtration model. Mainstream flow interacts with the series of backward-facing steps formed by the branchial arches. The resulting vortical flow interacts with the gill rakers to concentrate particles in zones 1 and 3 along the slot margins. BA, branchial arch; Fi, filtrate; GF, gill filament; GR, gill raker; MF, mainstream flow; Vo, vortex. This figure is not covered by the CC BY licence. [a,d © Virginia Greene/virginiagreeneillustration.com; b, © Kevin Schafer/kevinschafer.com; c, © Doug Perrine/SeaPics.com.] All rights reserved, used with permission.
