Sea urchins are spherical, hemispherical, heart-shaped or disc-shaped, and the colors are green, olive, brown, purple and black. Sea urchins are warm benthic species, living in reef forests or cracks in the sea below the intertidal zone rich in algae, and in hard and muddy shallow waters. Lurking in the mud during the day, coming out at night, crawling on the seabed with feet and thorns for food, and grinding food with a chew. The main food is seaweed, sponge and hydra.
The internal organs are contained in 1 shell, which is composed of many calcareous bone plates that are tightly healed. The shell is covered with many movable thorns. Each pair of pin holes on the shell plate is equivalent to 1 pin, and multiple rows of Hyderabad landscape are 10. The mouth is below, and there are five white teeth in the center, which are part of the chewing organ-Aristotle's lantern. 1 sea urchin shells are made up of about 3000 small plates.
Sea urchins, also known as stinging pots and sea hedgehogs, are spherical in shape, just like purple prickly cacti, so they have always been nicknamed "assassins in the sea". Fishermen often call it "underwater tree ball" and "dragon palace hedgehog" There are about 850 species of sea urchins in the world, and there are about 150 species along the coast of China. Common ones are horse dung sea urchin, Dalian purple sea urchin, heart-shaped sea urchin and carved sea urchin.
Sea urchin is an ancient creature in the ocean, which is closely related to starfish and sea cucumber. According to scientific research, it has existed on the earth for hundreds of millions of years. Due to the passage of time, the fossils of sea urchins were found on the Qinghai-Tibet Plateau in China. They live in the world's major oceans, with the Indian Ocean and the Pacific Ocean being the most frequent. Because they like sea areas with high salinity, they are rarely distributed near rivers and low salinity seawater, or not at all.
Sea urchins like to live in reef forests or crevices in the sea below the intertidal zone rich in algae, and in hard and muddy shallow waters, hiding in crevices, reefs, sediments or coral reefs. It has the habit of backlighting and staying up at night, relying on thorns to defend the enemy.
The spines of sea urchins are long and short, sharp and blunt, and the structures of spines are different with different species. Hainan Island coral reef is rich in a kind of stone pen sea urchin, which looks like a blooming flower, commonly known as cigarette holder sea urchin. It can be used as a cigarette holder because of its thick thorns. Some kinds of thorns are very long, reaching more than 20 centimeters.
Some sea urchins look much more beautiful than nontoxic sea urchins. For example, the ring-spined sea urchin, which grows between coral reefs in the South China Sea, has black and white stripes on the thick spines and yellow stripes on the thin spines. Young sea urchins have white and green ribbons shining on their spines, and a barb grows at the tip of the fine spines. Once it penetrates the skin, the venom will be injected into the human body, and the fine thorns will break in the flesh, causing local redness and pain of the skin, and some even have poisoning symptoms such as accelerated heartbeat and general spasm.
Sea urchin is a spiny animal, but it is very timid. As long as it sees the enemy, it will run away. Because they are born timid.