Biological complexity: fish filters for eating (Introduction)

by David Turell , Friday, April 01, 2016, 00:33 (3159 days ago) @ David Turell

Some fish have a complex filtering system for eating tiny organisms, a better filtering system than we humans use for many applications: - http://www.nature.com/ncomms/2016/160329/ncomms11092/full/ncomms11092.html - "Suspension-feeding fishes such as goldfish and whale sharks retain prey without clogging their oral filters, whereas clogging is a major expense in industrial crossflow filtration of beer, dairy foods and biotechnology products. Fishes' abilities to retain particles that are smaller than the pore size of the gill-raker filter, including extraction of particles despite large holes in the filter, also remain unexplained. Here we show that unexplored combinations of engineering structures (backward-facing steps forming d-type ribs on the porous surface of a cone) cause fluid dynamic phenomena distinct from current biological and industrial filter operations. This vortical cross-step filtration model prevents clogging and explains the transport of tiny concentrated particles to the oesophagus using a hydrodynamic tongue. Mass transfer caused by vortices along d-type ribs in crossflow is applicable to filter-feeding duck beak lamellae and whale baleen plates, as well as the fluid mechanics of ventilation at fish gill filaments. - *** - "Our cross-step filtration model based on paddlefish and basking shark morphology takes advantage of vortical flow in porous slots to reduce clogging by concentrating particles along the slot margins. Furthermore, by varying model parameters, we show that modified configurations can generate vortices that suspend and transport concentrated particles. - *** - "As more than 30,000 fish species possess branchial arches that may form d-type ribs, potential vortex formation in the slots between branchial arches has substantial implications for the fluid dynamics of fish feeding and ventilation throughout ontogeny and evolution. Vortical cross-step filtration could be applicable to feeding in a diversity of fish species. In addition, many filtration structures involved in vertebrate suspension feeding are composed of d-type ribs in crossflow, including fish gill rakers, tadpole gill filters, bird beak lamellae and whale baleen plates, suggesting that principles of vortical cross-step filtration could have widespread application." - Comment: A very complex engineering article which basically says directed vortices of water flow keep the filters clean, a system better than current human inventions for filtering. How is a natural process of evolution able to invent such complex solutions better than thinking humans seem able to do? Possibly a better mind behind it all.