Their tests (hard shells) are round and spiny, typically from 3 to 10 cm (1 to 4 in) across. Sea urchins move slowly, crawling with their tube feet, and sometimes pushing themselves with their spines. They feed primarily on algae but also eat slow-moving or sessile animals.

2015年8月22日 · One look at a sea urchin and you can see why they would be called sea hedgehogs. They have hard rounded shells covered with sharp movable spines. Urchins are part of the phylum Echinoderm and their name comes from Ancient Greek (echinos meaning "hedgehog" and derma meaning "skin").

2025年1月11日 · A sea urchin’s body is covered by a rigid shell or test comprising fused plates of calcium carbonate. It is encased in a thin epidermis, followed by a dermis and a thin layer of muscle and skin.

2023年5月22日 · The shells provide protection, camouflage, and defense mechanisms, allowing sea urchins to thrive in diverse marine habitats. Understanding the significance of sea urchin shells helps us appreciate the intricate adaptations and ecological roles of …

2025年1月9日 · Sea urchin, any of about 950 living species of spiny marine invertebrate animals (class Echinoidea, phylum Echinodermata) with a globular body and a radial arrangement of organs, shown by five bands of pores running from mouth to anus over the test (internal skeleton).

2025年1月23日 · The sea urchin shell, scientifically known as a test in the Echinoidea class, is found in about 950 living species worldwide. Sea urchin shells act as intricate protective armor. They help these marine organisms survive in various underwater environments.

2023年5月11日 · Sea Urchin Characteristics: Sea urchins have a spherical or globular body shape covered in spines. They possess a hard, calcareous outer shell called a test, which provides protection. Sea urchins have a water vascular system that aids in locomotion, feeding, and respiration.

Sea urchins are spiny, hard-shelled marine creatures found on rocky ocean floors worldwide. About 700 different species of sea urchins are known to exist throughout the world, having varied body colors, shapes and sizes.

2018年5月7日 · A sea urchin's spines surround its round inner shell, called a test, and rotate on ball-and-socket joints. They are coated in cilia, tiny hair-like structures, that wave to create a water current carrying food to the urchin's mouth and washing away waste.

Sea urchins tend to be small, globular, and have their soft internal organs protected by a hard, internal, calcite shell, or test, made of plates (calcitic ossicles) fitting closely together and located under the skin. Their test is round and spiny, typically from 3 to 10 centimeters across.