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    Sea urchin - Wikipedia

    Sea urchins or urchins are typically spiny, globular animals, echinoderms in the class Echinoidea. About 950 species live on the seabed, inhabiting all oceans and depth zones from the intertidal to 5,000 metres (16,000 ft; 2,700 fathoms). Their tests (hard shells) are round and spiny, typically from 3 to 10 cm (1 to 4 in) across. … 展开

    Sea urchins are members of the phylum Echinodermata, which also includes starfish, sea cucumbers, sand dollars, brittle stars, and 展开

    Life history 图像
    Ecology 图像

    Musculoskeletal
    The internal organs are enclosed in a hard shell or test composed of fused plates of calcium carbonate covered by a thin dermis and 展开

    Reproduction
    Sea urchins are dioecious, having separate male and female sexes, although no distinguishing features … 展开

    Fossil history
    The earliest echinoid fossils date to the Middle Ordovician period (circa 465 Mya). There is a rich fossil … 展开

    概览 图像
    Systems 图像
    Description 图像

    Urchins typically range in size from 3 to 10 cm (1 to 4 in), but the largest species can reach up to 36 cm (14 in). They have a rigid, usually spherical body bearing moveable spines, which give the class the name Echinoidea (from the Greek ἐχῖνος ekhinos 'spine'). The … 展开

    Evolution 图像

    Trophic level
    Sea urchins feed mainly on algae, so they are primarily herbivores, but can feed on sea cucumbers and a wide range of invertebrates, such as 展开

    Injuries
    Sea urchin injuries are puncture wounds inflicted by the animal's brittle, fragile spines. These are a … 展开

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  2. Sea urchin | Description, Anatomy, & Facts | Britannica

    2024年10月5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 …

  3. Sea Urchin - Description, Habitat, Image, Diet, and Interesting Facts

  4. Sea Urchin - A-Z Animals

  5. Sea Urchin - Animal Corner

  6. Sea Urchins - National Geographic

    2009年11月12日 · See photos of sea urchins (including fire urchins, pencil-spined urchins, and more) in this oceans life photo gallery from National Geographic.

  7. Sea urchins: Strange and spiny wonders of the ocean

    The most easily recognisable sea urchins are round, often brightly coloured and covered in sharp-looking spines. In fact, ‘urchin’ comes from an old word for hedgehog owing to their similar-looking spiky armour. However, there are …

  8. Sea Urchin: The Marine Invertebrate - Ocean Info

    Learn about sea urchins, spiny creatures that belong to the phylum Echinodermata. Find out their appearance, diet, habitat, reproduction, threats, and more.

  9. Green Sea Urchin | Online Learning Center | Aquarium of the Pacific

  10. Sea Urchin Anatomy - Ask A Biologist

    2015年8月22日 · Sea Urchin Anatomy. 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 …