The red swarmer evolved from the river swarmer. The red swarmer evolved a digestive system that enabled them to eat plants. They evolved a small sharp tooth on the front of their mouth with which they could scrape off pieces of the plant. The male red swarmers were becoming bigger than the females and also developed a red pattern on their skin. The females look more like their ancestors, but the only males they wanted to mate with now were the biggest and reddest of all red swarmer males. Over many years, the males were becoming bigger and redder; they even evolved a large, red back-fin to attract even more females.