Snowploughs And Rotsuckers

Nature abhors letting a resource go to waste, and the deluge of organic material in the lower water levels from the Time of Hunger was too great an opportunity for the herring to pass up. As the scavengerkin expanded their niche to better exploit this new food source two distinct species groups began to evolve.

The Rotsuckers have adapted to life in the benthic zone (the seafloor), where the food is thickest but the oxygen is lowest. Due to easy access to food, low oxygen levels and no predators, they have become slow moving fish, lazily gliding over the seafloor with broad sweeps of their tails. Their mouths are angled slightly downwards, acting similar to the nozzle of a vacuum cleaner. Loose pieces of marine snow are sucked inside, with water being expelled through the gills. Extending their jaws creates a set of ‘lips’, which the rotsucker can use to engulf larger pieces of flesh and suck them off the bone. With their lack of sharp teeth they can only bite off well-rotted, soft flesh, allowing the water and bacteria to carry out a form of pre-digestion for them.

Rotsuckers possess primitive barbels on their chins. Little more than short fleshy whiskers, these barbels are used to detect the seafloor beneath as the fish is swimming over it, allowing it to stay a level distance above the seafloor and not swim too high/dive straight into a chasm.

Due to their choked and polluted environment rotsuckers have a high tolerance for anoxia, albeit at the cost of their metabolism, making them quite sluggish fish. When moved into oxygenated waters they become agitated due to the sudden flush of oxygen in their bloodstreams. Exposure for an extended period of time may even cause death due to over-exertion.

The Snowploughs exist in the demersal zone, above the benthic zone. Unlike the rotsuckers they are free swimming fish, and thus have a body plan similar to their herring ancestors. Snowploughs get their name from their method of feeding: they are filter feeders who glide through the clouds of marine snow, swallowing clumps of organic matter. When feeding both upper and lower jaws extend outwards, creating a funnel shape that scoops up the drifting snow. Unlike the rotsuckers- who have to pause eating in order to flush out swallowed water- snowploughs are capable of feeding continuously. Their gill rakers- bony processes attached to the gill arches- have increased noticeably in size and number from their herring ancestors. Swallowed water passes through the rakers, which catch suspended organic matter. The water is then passed out through their gills, with the organic matter directed down the oesophagus.

Snowploughs are making a considerable contribution to the healing of the oceanic ecosystem after the Time of Hunger. They remove large quantities of marine snow from the water column, and their swimming motions help to mix oxygenated water with the anoxic layer below. This will of course cause them to be victims of their own success, as their food supply dwindles and the ecosystem stabilises to healthier levels. Their filter feeding abilities however will ensure a very successful future for their descendants.