Image credit: Queensland Brain Institute, The University of Queensland
Put down that plate of calamari! For the first time, Dr Wen-Sung Chung and Professor Justin Marshall, from the University of Queensland’s Queensland Brain Institute have created a map of a reef squid’s brain. Based on the number and variety of connections, it seems that squids have brains roughly analogous to that of a dog.
This news may be surprising to those who tend to view invertebrates as inherently simple creatures, but cephalopods, a family that includes octopodes, cuttlefish, and squid, are here to disprove that idea.
The remarkable intelligence of the octopus is a well-known fact in the science world, but as far as deep-sea creatures go, octopodes are relatively easy to study. Their sea floor den habitat is easy enough to recreate in a lab setting, and they’re very familiar manipulating shells and rocks, a habit which can provide the basis for any number of scientist-created puzzles.
Squids, on the other hand, live in the wide open ocean—a much harder environment to mock up inside a lab. Their lifestyles are also much more mysterious to us, which complicates devising a suitable intelligence test. How do you measure the IQ of a creature when you don’t even fully understand what they use their intelligence to do?
Hence, the use of MRI-mapping to explore the brains of these mysterious creatures. “This is the first time modern technology has been used to explore the brain of this amazing animal,” said Dr Chung, “and we proposed 145 new connections and pathways, more than 60 percent of which are linked to the vision and motor systems.”
Another area of squid expertise? Camouflage. Squid skin is covered in tiny dots called chromatophores, which can turn yellow, red, brown, and black, and beneath those are iridophores and leucophores, which can reflect light and turn blue, green, or white. Somehow, squid can use these to mimic their surroundings, despite the fact that squid eyes are color-blind. One theory holds that squid skin itself can detect some light and color on its own, bypassing the eyes; unlike vertebrates, cephalopods have decentralized nervous systems.
“We can see that a lot of neural circuits are dedicated to camouflage and visual communication. Giving the squid a unique ability to evade predators, hunt and conspecific communicate with dynamic colour changes,” Dr. Chung said.
The mapping also appears to give more credence to our current understanding of convergent evolution, in which different animals independently develop similar features, like bat wings and bird wings. In this case, it seems that cephalopods evolved a form of intelligence fundamentally different from ours. The squid brain contained neural networks unlike those seen on vertebrates.
“Our findings will hopefully provide evidence to help us understand why these fascinating creatures display such diverse behaviour and very different interactions,” said Dr. Chung.