Entities › Animals and other organisms › Nerve nets, no brain

Box jellyfish

Tripedalia cystophora

A box jellyfish has no central brain, yet it showed associative learning.

Neurons

No published count

Evidence

• It showed associative learning (a visual cue paired with a mechanosensory cue). The learning happens in the rhopalial nervous system, even though the animal has no centralised brain.
  Bielecki J, Dam Nielsen SK, Nachman G, Garm A (2023) Associative learning in the box jellyfish Tripedalia cystophora. Curr Biol 33(19):4150-4159.e5. doi:10.1016/j.cub.2023.08.056.

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