Feathercombing Gilltail
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The feathercombing gilltail split off from common gilltails. While its ancestors were already planktivores, they had no apparatus for filter-feeding, instead catching individual particles by sight. The feathercombing gilltail has no such apparatus either, but it has evolved to be able to filter-feed nonetheless with a novel strategy—tool use.
More specifically, the feathercombing gilltail seeks the fallen flight feathers of flying saucebacks such as the albedophrey and the hippogryph, usually located near beaches, and uses them to catch food. It can also use pinyuk feathers, but sauceback feathers are preferred, as they are more resistant to water damage. After it finds a feather, it uses its beak to separate the barbs. It then grips the feather with its beak and swishes it through clouds of microscopic plankton. Microswarmers, unicellular organisms, and the eggs and larvae of much larger creatures become caught on the hooklets lining each feather barbule, like a scaled down version of a creature becoming caught in a bramble. The feathercombing gilltail then uses its beak to comb through the barbs and remove the plankton from the feather to eat, which is where its name comes from. This allows it to take in similar amounts of plankton to more specialized filter-feeders, while also not inhibiting its ability to eat larger morsels.
Outside of this, the feathercombing gilltail has slightly longer trailing gill surface to improve streamlining and boost the oxygen entering its bloodstream. This results in its gill exits looking "backwards" compared to other gilltails. It also has a more robust and hooked bill, partly to grip feathers and partly to help it get through exoskeletons.
Much like its ancestor, the feathercombing gilltail is migratory, having distinct summer and winter ranges. In the winter, it stays near the tropics and subtropics of eastern Darwin. It migrates north for the northern hemisphere's summer, crossing a short stretch of open sea by taking advantage of favorable currents and passing through Soma to reach the subpolar mangals of Drake's coastline. During its stay, it breeds, hiding its eggs among rocks and sand, as well as feasts on vast blooms of local plankton, sifting them from the water mainly using albedophrey feathers. It is social and it lives and travels in shoals.