The creature has taken a liking to bigger prey, and sometimes, these bigger creatures are too much. The creature eventually evolved to becoming more mobile, in a sense that it uses its tripod legs to swim, well, more like bob through the water until its poison tentacled arms could hit a target. When it finds a bigger prey, it’s mouth has grown small teeth and lip-appendages to help it attach itself to the prey. It helps clamp down on smaller and more agile prey as well. It’s eyeballs have developed further to have slit eyeballs for depth perception. Since it can’t really swim after faster prey, it stalks most of its prey to be poisoned, or stalk it until it dies from the poison. Its hide has grown thick and almost rubbery since it takes a lot of beating while attached to other animals.