? Sea urchins are creatures that live in the ocean. They look like plants and basically do not move, so many people think they belong to plants. In fact, sea urchins are actually animals. In terms of classification, sea urchins belong to the animal kingdom, and all creatures in the animal kingdom belong to animals, so do sea urchins. Animals and plants are relative concepts, and the living things in the plant kingdom are plants. Sea urchins, as animals, are quite different from plants.
In terms of movement, although sea urchins do not move in the water for a long time, they actually move, but the speed of movement is relatively slow. Sea urchins rely on a few tubular feet and spines on their bodies when they move, but plants are basically immobile. In addition, at the micro level, the cells that make up sea urchins are also very different from those of plants. There is no cell wall in the cell composition of sea urchins, but there is a cell wall in plant cells. Moreover, many plants have chloroplasts that can be used for photosynthesis, but sea urchins do not have such structures.
are sea urchins? As mentioned above, sea urchins belong to animals. In terms of specific classification, sea urchins belong to the phylum Echinodermata, which is a kind of echinoderm. Sea urchins, as echinoderms, also conform to the basic characteristics of echinoderms. For example, from the appearance, echinoderms are basically radial symmetry, and sea urchins also conform to this feature. For example, echinoderms generally have aqueducts in their bodies, as do sea urchins.
In addition, sea urchins can be divided into marine animals according to their living environment, because sea urchins basically live in the ocean. Specifically, sea urchins are widely distributed all over the world. Some sea urchins are distributed in relatively shallow places, while others live at depths of thousands of meters and have diversity. In terms of feeding habits, sea urchins are omnivores. They can eat algae in the water, as well as hydras, worms and other animals.
