The giant swarmer split from the river swarmer to live in deserted Hydro-Nuke Lake, the swarmers only having adapted from salt-water to fresh-water one species ago, the opposite occurred quite easily. The salt water was enough to keep competition back, and predators willing to stray into the waters were few. The swarmers managed achievements in the area, including an increase in size. This is partly because of sexual reasons (sharing the same ancestor as the red swarmer), and also because a bigger body allowed for a more complex and longer gut, letting them digest larger food with the filter system, so they can eat on more things floating about. Now they can eat chunks of dead matter that flows in from the rivers. They also developed a more feeble area between their thorax and "tentacle fins", giving them flexibility for more advanced swimming. Their camouflage is of little importance anymore, and is mostly there for, again, courting reasons.