Latuscauda

Even more organisms from my ongoing Priapus Prime Project. These guys are a couple examples of animals from the family Latuscauda, meaning "broad-tail." These two are members of the two most prominent species, one living in the shallows and one living in lakes and rivers. They are characterized by their long, flat tails which they use to propel themselves through the water. Like all fluidoderms, they are descended from radially symmetrical organisms and thus have five eyes. As per the usual arrangement in bilateral fluidoderms, they have one facing forward and two pairs of stalk eyes. Often Latuscauda have a pair that is longer than the other, though some species have pairs of eye stalks that are the same height. The larger ones are retracted when beneath the water to reduce drag, and are used to keep a lookout for predators while on land (they can move independently, if you didn't guess). Underwater the smaller pair and lone eye work together for trinocular vision and depth perception.

The bigger one, which I used to show the basic body plan shared by all Latuscauda, is a bit like a walrus in terms of its niche. It's a large creature, about the size of a manatee, though their tail makes them about a meter longer. These guys have big, scary tusks on their enlarged upper pair of pseudoradula, though they are not as pronounced in females. Males use them to fight for mates, and both males and females will use them to ambush larger prey on the shore during times when xenoichthys are scarce. This species in particular lives in the shallows between the Peninusla and the Island, though some sub-species have adapted to life in the open ocean and on various small islands and archipelagos. Most of them have webbing between their pseudoradula to prevent xenoichthys from swimming away to either side when being caught, and four hook-like structures can extend from the bottom, making a kind of cage to keep them from swimming out once in the oral cavity.

The smaller one, of which I only depicted the face, is radically different. They are a lot smaller, about the size of a capybara, (again, longer because of the tail) and much more intelligent. Rather than have tusks, their upper pair of pseudoradula have adapted into scissor-like cutting implements, which they use to harvest bamboo-like water plants. On occasion they feed on these plants, but their main use is for building large structures like beaver dams, although these are more complex. These structures are labyrinth-like, and often built far away from shade. The maze keeps marine predators out, but also confuses xenoichthys, who gather in the structure for the shade. The xenoichthys are then herded into the central chamber, which usually has a lower water level than the body of water it is built in. They end up trapped, and are stored as a source of food (and hunting practice) for youngsters who are not yet old enough to seek their own prey.