Are Squid Smart? What Squid, Cuttlefish and Octopus Studies Show

Are squid smart? Yes, by the few tests that exist, though no squid has an IQ. A Hawaiian bobtail squid learned to hold back an attack in one 10-minute trial and, after three trials, remembered it for at least 12 days. Cuttlefish waited 50 to 130 seconds for a better meal. No test has put squid and octopuses side by side.

New here: the squid evidence is the thinnest of the group. A 2017 paper called its result the first demonstration of associative learning in any squid, to the authors’ knowledge. The best like-for-like comparison is brain size across 79 cephalopod species, and it was linked to habitat. Below: what each study measured and what it did not.

Key takeaways

• Learning: a Hawaiian bobtail squid learned to inhibit its predatory behavior within one 10-minute trial and kept the memory for at least 12 days (Zepeda and others, 2017).
• Self-control: cuttlefish waited 50 to 130 seconds for better food, and the longest waiters did better at a learning task (Schnell and others, 2021).
• Brain size: across 79 cephalopod species, shallow, seafloor-living species had larger brains. Sociality did not predict brain size (Basava and others, 2026).
• IQ: none. No test of that kind exists for squid.

Are squid smart?

Yes, in the ways that have been tested, but few squid have been tested. How smart are squid? Smart enough to learn from one short session and to remember it for days.

Squid, cuttlefish and octopuses are all coleoid cephalopods. They have the largest nervous systems among the invertebrates (Albertin and others, 2015). Their brains evolved separately from ours, from a common ancestor more than 500 million years ago, as our octopus page notes.

Most of the cognition work has used octopus and cuttlefish. The 2017 squid paper itself says there had been relatively little work on squid. As far as we found, no single task has been run on squid, cuttlefish and octopuses alike, so every claim here comes from a different test.

Are squid smarter than octopus?

Nobody knows, because no test has compared them. Squid vs octopus intelligence has not been measured on one task.

The 2026 study of 79 species is the nearest thing to a like-for-like comparison. It found that shallower and benthic (seafloor) habitats were associated with larger brain sizes, and that measures of sociality were not. The authors report habitat as the strongest ecological predictor of brain size, rivaling body size, and they do not treat it as causal.

That is a finding about habitats across 79 species, not a ranking of squid against octopuses. Both groups include many short-lived species that die after one breeding event and live largely alone. For the octopus evidence, with its neuron count, tool use and recognising people, see our octopus IQ page.

Can squid learn?

Yes. In 2017 Zepeda, Veline and Crook showed that a squid, the Hawaiian bobtail squid, learns and remembers.

They used the “prawn-in-the-tube” assay. Within a single 10-minute trial the squid learned to inhibit its predatory behavior. After three trials it kept that memory for at least 12 days. Learning and memory held under two different training schedules.

The authors call it the first demonstration of learning and memory in this species. To their knowledge it is also the first demonstration of associative learning in any squid. The animal is a small sepiolid squid, chosen because it breeds well in captivity and has a short generation time.

Do cuttlefish have self-control?

Yes, in one laboratory test. Cuttlefish self-control was measured in 2021 by Schnell, Boeckle, Rivera, Clayton and Hanlon with a delay maintenance task.

Cuttlefish were offered a worse reward at once or a better one later. They maintained delays for up to 50 to 130 seconds. The same animals then did a reversal-learning task, in which the reward moves from one stimulus to the other. Cuttlefish that delayed gratification for longer had better learning performance.

The authors write that cuttlefish can tolerate delays to get better food, comparable to some large-brained vertebrates. Cuttlefish are not squid, but they are close relatives, and this is the only experiment we read that tests self-control in a cephalopod.

Do squid have social lives, and does that make them smarter?

Some squid school, but social life does not explain cephalopod brains. In the 2026 study, whether a species was solitary or gregarious was not associated with larger brain size.

Sociality in cephalopods follows family lines. Schooling occurs only among squid, cuttlefish and their close relatives, and not in every species. None of the octopus species in the dataset were coded as gregarious.

Squid and cuttlefish also signal to each other. The authors write that communicative body patterns are used widely across them in mating contexts. Aggressive visual signaling and tactical deception have been observed in a range of species. That is a summary of the literature, not a test score.

Why would a loner have a big brain? The authors test the Asocial Brain Hypothesis. It says that even largely solitary animals can evolve bigger brains when learning pays off in calories. Shallow seafloor habitats are richer in food and variety than open water, and the study found larger brains there.

To build its table the team read all 3,933 papers in the Zoological Record and extracted data for 79 species with comparable adult brain measurements. Most species had only one brain and body measurement, so the results describe species, not individual animals.

How big is a squid's brain?

We found no published weight or neuron count for a squid species that we could read, so we give none. Squid brain size is known only in outline.

What the sources do say is this. Octopuses, squid and cuttlefish have some of the largest brains relative to body size among invertebrates (Basava and others, 2026). For scale, the common octopus has about 500 million neurons, about 300 million of them in its arms, against about 86 billion in a human brain.

Brain size is also not a score. A big brain is not the same as many neurons, a lesson our post on T rex brain size shows with a dinosaur.

Is there a squid IQ?

No. IQ ranks people against other people of the same age, and no test or norm group like that exists for squid. Any “squid IQ” number is invented. Without one, the question can only be answered study by study, as above.

To see what has been measured across species, read our smartest animals study and the news report on the smartest animal in the ocean. Other sea animals have their own pages: sharks, dolphins and orcas. To test your own reasoning, take the IQ test.

Quick answers

• Are squid smart? Yes, in the tests that exist. A bobtail squid learned and remembered for at least 12 days, and cuttlefish waited up to 50 to 130 seconds for better food.
• Are squid smarter than octopus? Nobody knows. No test compares them.
• Can squid learn? Yes. A Hawaiian bobtail squid learned within one 10-minute trial (Zepeda and others, 2017).
• Do cuttlefish have self-control? Yes, in one test: they waited 50 to 130 seconds, and longer waiters learned better.
• What is a squid’s IQ? There is none. No IQ test exists for squid.

Sources

• Zepeda EA, Veline RJ, Crook RJ (2017). Rapid associative learning and stable long-term memory in the squid Euprymna scolopes. The Biological Bulletin 232(3), 212-218 (abstract read).
• Schnell AK, Boeckle M, Rivera M, Clayton NS, Hanlon RT (2021). Cuttlefish exert self-control in a delay of gratification task. Proceedings of the Royal Society B 288, 20203161 (abstract read).
• Basava K and others (2026). Ecological not social factors explain brain size in cephalopods. iScience 29(7), 116324 (open access; full text read).
• Albertin CB and others (2015). The octopus genome and the evolution of cephalopod neural and morphological novelties. Nature 524, 220-224 (abstract read).
• Octopus and human neuron counts as printed on our octopus IQ page (Young, 1963).
• Photo: a squid at Gray’s Reef National Marine Sanctuary, Greg McFall / NOAA, 2007, public domain, via Wikimedia Commons.