Homesick jellyfish:
It turns out the jellyfish, even without a central nervous system, can see and can make an organized response to what they see. (Jellyfish eyes on the Sky NATURE vol. 473 no. 7345 page 8) Box jellyfish live among mangroves and use some of their numerous eyes to orient to the canopy above them. If they are displaced from their preferred location, they return to it. If they are displaced more than 8 meters, however, the system overloads and they get lost.
Obviously they have evolved to stay very close to home. “You go, jellyfishes; stick with them cousins.”
Blood is thicker than water even in creatures without blood.
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