Sea Chestnut
Have you ever looked downward toward the seabed while swimming in the sea and seen spiky, ball-like creatures? These are sea urchins, the spiky spheres of the oceans. Sea urchins are creatures that live throughout the world’s oceans and strongly prefer rocky habitats. They belong to a special group of animals that scientists call Echinoidea.
Where Do They Live?
Sea urchins can live in all oceans and seas. They are commonly found on rocky and stony seabeds in shallow waters, where they like to hide among rocks. Some species live in deeper waters.

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What Do They Eat? 🌿
The primary food of sea urchins is algae (small plants that live in water). They scrape these algae, which grow on rocks, using a specialized mouth structure called the Aristotle’s Lantern. Some species of sea urchins also feed on other small marine organisms such as mussels, sponges, or polychaetes. Therefore, they can be both herbivorous and carnivorous.
Body Characteristics 🐚
The body of a sea urchin consists of a spherical shell covered in spines. This shell functions as a skeleton. The spines are used for protection against predators and for movement. Although they have no eyes or legs, sea urchins can move easily across surfaces thanks to sticky appendages called tube feet.

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How Do They Grow? 🔬
Sea urchins are divided into males and females. When it is time to reproduce, males and females release eggs and sperm into the water. Fertilization occurs in the water, and new sea urchins develop from the fertilized eggs.

