The puffer fish is a bony fish, and the shark is a cartilaginous fish. So according to the traditional biological classification method, the lowest is octopus, followed by shark, and the highest is puffer fish.
In fact, biology has now diluted the classification of advanced and low levels. Sharks have existed for 65.438+0.8 billion years and have been at the top of the food chain, but they are lower than crucian carp in biology. In fact, the evolution of survival of the fittest, high and low has also been gradually diluted. Because organisms have no fixed evolutionary direction, for an environment, there must be one or more structures that adapt to the environment. When the environment changes, the interconnected structures will become cumbersome, and the originally cumbersome structures may become adaptive weapons. When the environment changes back, the later species will not be as heavy as before, but the first species to survive will become the adaptive champion again. Even if no species survived in the last round and the environment changed back, there would still be a similar strategy. For example, biological evolution is like a drop of ink on parchment, which will spread in all directions. The environment is like wax drops on parchment, which will hinder the ink from spreading in some directions. However, if we remove the wax drops, the ink will be quickly replenished from around to fill the space where the wax drops are removed. If you just look at the fixed position of the wax droplet, you can judge that the place near the center of the ink droplet will spread first, and the direction of diffusion is from the center to the outside. However, when observing the change after the wax drop is removed, you will see that the ink spreads from all sides to the center of the wax drop. The diffusion direction here is completely different from the original one, but it is all realized under the same principle. That is to say, there is no distinction between the positions (analogy species) on the parchment, which determines the order in which they appear (analogy diffusion). That is, whether their adjacent positions have been diffused (like parchment soaked in ink) or waxed (like the adaptability of species to the environment). As long as these two conditions are met, the species will certainly appear, regardless of whether there are other species "higher" or "lower" than it.