Remucauda subaquatica
This descendant of Castorocauda flumum resides in the creeks and rivers of Zone 14. It is slightly larger at twenty centimeters (20 cm) in length to help it in its new lifestyle. Castorocauda subaquatica has a broader tail and a larger and thicker fluke that now enables for suitable swimming in Zone 14, where it is safe from predation. Although Bulbus litorus makes up a small part of its diet, whether it is stems in the water or if they are on land, it also feeds on Bulbus aciecrescus (Bankshroom) and Bulbus flumuancoris (Tripad) as its main diet.
Castorocauda subaquatica typically feeds from the water by diving downwards with its fluke, taking nips at stems with its beak, and resurfacing to breathe every few seconds. It has buoyancy from the oxygen it stores and can resurface itself if caught in rapid river currents.
The closer end of the upper beak appears to bend around the face of Castorocauda subaquatica. It has no distinctive function and seems to have risen from random chance, although it may provide some protection in the case that Castorocauda subaquatica were to collide with a large rock, and the beak may absorb some of the force rather than the much softer body. It is kept as it provides a slight benefit to absorbing force in those who have it.
When it is time to reproduce, Castorocauda subaquatica will go on land and they will feed from Bulbus litorus in the meantime. They start this at the age of six (6) weeks and spend no longer than a week exclusively on land for that purpose, although surviving individuals may repeat this every six (6) more weeks to maximize their genetic potential. Males pair up with females and reproduce by sliding their cloacas next to eachother, the male releasing sperm into the female to impregnate her.The female will lay between fifteen (15) and twenty-five (25) soft eggs in total in soil away from where it erodes to ensure that eggs are not swept away. Several generations may reproduce within a year.
As the young are not large enough to efficiently swim against currents on their own, they will stick onto land and feed from Bulbus litorus on the river shorelines until they are four (4) weeks of age, when they are large enough to swim on their own at fourteen centimeters (14 cm) in length, and head into the water then to feed on Bulbus aciecrescus and Bulbus flumuancoris.
Castorocauda subaquatica retains the instinct of hibernation at low temperatures but does so later in the year as the water has more consistent temperatures than the air. When the water is twelve degrees Celsius (12°C) or lower in temperature, it will go onto land and bury itself underneath sediment for insulation and to conserve energy while its sources of food are less common.