Year 2021 đ
Hydra belong to a larger group of invertebrates called cnidarians, which also includes sea anemones, corals, and jellyfish. Their simple bodies have a tubelike shape with the mouthpart and tentacles at one end, and a âfootâ that attaches to the surrounding rock or other solid surface at the other.
Some animals such as lizards and salamanders can regrow lost limbs. But hydra, along with some worms and other animals, take regeneration to the extreme. Near their mouthparts, hydra have a cluster of 50 to 300 cells called the head organizer; as its name implies, it directs the development of the head. If a hydra is beheaded, a new organizer can form and prompt the animal to regrow its head. Meanwhile, the head that was lopped off will sometimes regrow the lower portion of its body.
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