No brain, no problem: Tiny jellyfish can learn from experience

Tiny caribbean box jellyfish are capable of learning from visual cues to avoid swimming into obstacles -- a cognitive ability never before seen in animals with such a primitive nervous system

Caribbean box jellyfish are barely a centimetre long and have no brain.

But these gelatinous, fingernail-sized creatures are capable of learning from visual cues to avoid swimming into obstacles -- a cognitive ability never before seen in animals with such a primitive nervous system, researchers said on Friday.

Their performance of what is called "associative learning" is comparable to far more advanced animals such as fruit flies or mice, which have the notable benefit of having a brain, the researchers said.

The Caribbean box jellyfish, or Tripedalia cystophora, is known to be able to navigate through murky water and a maze of submerged mangrove roots.

These scenarios throw up plenty of dangers that could damage the jellyfish's fragile gelatinous membrane which envelops its bell-shaped body.

Also Read | India adds 664 animal species to its faunal database in 2022, 339 taxa to its flora

But they avoid harm thanks to four visual sensory centres called rhopalia, each of which has lens-shaped eyes and around a thousand neurons.