The Sea-Sweeper

Porplets and their relatives - aberrant plant-eating dolfinches, of which we have so far seen a handful of species - have until recently been small animals. Living in large groups, they are migratory and would simply swim off to new pasture when they have grazed all that they can in an area. But the ocean age’s productivity has increased available green food for consumption, and while some porplets have merely increased in population, other related species have begun to grow much, much bigger.

Sea-sweepers are the closest living relatives of the porplet group. Like porplets they can digest plant matter, but their specialization is less and they prefer to suck up soft clumps of algae to chewing vascular plants. This would be because in addition to grazing on such vegetation the sea-sweepers are omnivorous proto-filter-feeders, the keratin teeth on their upper jaws and tongues being long and bristle-like, suited to sieve plankton from seawater much more so than to chew on hard food.

Sea-sweepers are generally substantial creatures, with several growing more than twenty feet in length and the largest, the spotted sea-sweeper, can grow as long as forty feet (12 meters) in length, making it one of the biggest animals on Serina at this time and among the largest birds so far. Living in closely associated groups, their size and gregarious nature are considerable defences against all but the very largest of oceanic predators.

The spotted sea-sweeper has an over-long lower jaw, which curves down and slightly up like a scythe and is used to sweep side to side in low-growing aquatic vegetation to disturb small fish and invertebrates, which the sweeper then engulfs in its wide mouth and seins from the water with its teeth. Other sea-sweepers have elongated lower beaks to less extreme degrees and all feed in this manner, taking a wide variety of foods and so having a generalized digestive system.