is sea urchin? Sea urchin is a common animal and a very famous animal. In terms of biological classification, sea urchins belong to the phylum Echinodermata in the animal kingdom, that is, echinoderms. Echinoderms have some common characteristics, for example, they are all invertebrates and have no spine in their bodies, and the same is true of sea urchins, which have no spine. And echinoderms are generally radially symmetrical in appearance, as are sea urchins, which can be clearly observed when observing them.
Sea urchins are also animals that live in the sea. Because of their variety, they are distributed in many sea areas around the world. Sea urchins are also omnivores. They can eat both plants and animals. The most common plants they eat are algae. The animals they eat are generally small, such as worms, hydras and so on. The sea urchin is also an animal that has existed for a very long time. It has been around for a year.
? As mentioned above, sea urchins belong to echinoderms and are invertebrates. Fish refers to animals in the fish class of the phylum Chordata, which are vertebrates. It is obvious that the sea urchin is not a fish, but a much lower animal than a fish. Specifically, there are many differences between sea urchins and fish. The most obvious difference is the presence or absence of a spine. Fish are vertebrates and have a spine in their bodies, while sea urchins are invertebrates and have no spine in their bodies. For example, from the point of view of breathing, the two are also different. Fish have special gills and use gills to breathe, while sea urchins have special external gills and tube feet to breathe.
