Why are cephalopods so smart?

[lpetrich]

Friday Cephalopod: Why are some cephalopods so clever? noting Grow Smart and Die Young: Why Did Cephalopods Evolve Intelligence? - ScienceDirect PZ Myers: "It’s a topic I’m very interested in, but the article fell flat for me. I’m going to be a bit nit-picky here."

It is a review article, one that reviews various hypotheses for the origin of intelligence: ecological, social, and predator-avoidance. The ecological one is about trying to get scarce or difficult-to-extract food. PZ found it too speculative, among other problems.

But. Here’s what bugs me: it’s comparing a whole taxonomic class, the cephalopods, with a couple of families. The cephalopods are diverse, with some impressively intelligent representatives, like the octopus. But market squid? Are they particularly bright? I don’t think so. We could say the same of primates — are we really going to compare Galago with Homo? This table would have benefited from a much tighter focus.

It also leaves out some features unique to various groups. Can we compare complex active camouflage with complex language?

PZ did like the paper's comparison table, however.

	Trait	Cephalopods	Corvids	Cetaceans	Apes
Morphology	Manipulative appendages	Suckered arms and tentacles	Beak and feet	Rostrum	Hands
	Dexterity	High	High	Limited	High
Senses	Vision	High	High	High	High
	Acoustic	Limited	High	High	High
	Smell, chemotactic	High	Limited	Limited	Limited
Brain	Brain-body size ratio	High	High	High	High
	Substrate for complex cognition	Vertical lobe	Nidopallium	Cortex	Cortex
Ecology	Lifestyle	Aquatic	Flight	Aquatic	Terrestrial/arboreal
	Diet	Carnivores	Generalistic	Carnivores	Generalistic
	Extractive foraging	Present	Present	Absent	Present
	Predation	High	Limited	Limited	Limited
Social life	System	Solitary/anonymous schools	Pairs/groups	Family groups	Groups
	Long-term bonds	Absent	With pair mate	With multiple individuals	With multiple individuals
Behavioral flexibility	Find and process food	High	High	High	High
	Social interactions	Limited?	High	High	High
	Predator avoidance	High	?	?	?
Life history	Lifespan	0.5 - 2 years	>15 years	>40 years	>40 years
	Parental care of offspring	Absent	Present	Present	Present
	Reproduction	Semelparous strategies	Iteroparity	Iteroparity	Iteroparity

A note on terminology: rostrum = snout, generalist = omnivore. Corvids are crows and close relatives, while apes include us.

The problem of limited representation also occurs for cetaceans, where only a few species have been studied in any detail. The best-studied one is likely the bottlenose dolphin (Tursiops truncatus), and these and some other cetaceans have snouts, long thin forward parts of jaws. Another well-studied one, the orca or killer whale (Orcinus orca), has a more rounded jawline without a snout, something at least as common among cetaceans.

 

[Angry Floof]

I don't know why they're so smart, but I fully expect to one day welcome our new cephalopod overlords.

 

[lpetrich]

I'll now go through these traits.

Manipulative appendages -- hard to compete with cephalopod ones. Of land animals, only elephants have anything like them, but they have only one each.

Unlike the other three, cetaceans are low on dexterity.

All are good at vision, and vision requires a lot of brainpower to interpret in any detail. Computerized image processing also requires a lot of CPU power.

All but cephalopods are good at hearing. Dolphins have a lot of brainpower dedicated to interpreting echoes from their clicks, and they have a little bit of vocal language. They name themselves, and they make imitations of the echoes of objects.

Smell does not seem very necessary. Chemical senses do not require much brainpower to process, if any.

But relatively large brains are necessary for high intelligence.

As to diet, carnivory is necessary for large open-water animals, since there is not much macroscopic ocean vegetation. This is even true of filter feeders, like baleen whales. Their filters are not fine enough to catch open-water algae, so instead they eat small crustaceans and the like, which feed on the algae. But on land, there is plenty of large vegetation, something that enables many large land animals to be part-time or full-time herbivores.

Extractive foraging is such things as pulling open bivalve shells, as octopuses are known to do. Crows and some other birds will drop nuts and shellfish and turtles to crack their shells. Avian prey-dropping behavior. II. American crows and walnuts | Behavioral Ecology | Oxford Academic - crows are careful to avoid flying too high, to save energy and to avoid risking others stealing their cracked nuts. Likewise, chimps and some monkeys will crack nuts with stones.

Dolphins are not known to do such things, however.

Cephalopods are much more vulnerable to predation than the vertebrates in the table, and their predator-avoidance adaptations are much greater. Octopuses can camouflage themselves, making themselves resemble their environments -- a variety of environments. Corvids, cetaceans, and apes have much less. Many cetaceans are countershaded, with light-colored bellies, but that's about as far as it goes. Cryptic coloration is good for predators as well as for prey, so one has to be careful with that criterion.

The vertebrates in the table are moderately to highly social, and they often have long-term social relationships. Cephalopods have very limited social lives, however. Octopuses are solitary, and many squid swim in large groups with little social interaction.

Cephalopods suffer a cruel biological joke that needs a bit of explanation.

Among organisms' life histories, there are two main variations: semelparity and iteroparity. The first is reproducing once and soon dying, and the second is reproducing repeatedly. Among plants, annual plants are typically semelparous, while perennial ones are iteroparous. Among octopuses, a female one reproduces only once while a male one may reproduce more than once. A female octopus lays her eggs in some underwater cave or similar spot, and then guards those eggs, never eating. When the eggs hatch, she dies. That is the extent of parental care among octopuses -- not very much.

This means that octopuses do not have any opportunity to learn from their elders.

 

[lpetrich]

I don't know why they're so smart, but I fully expect to one day welcome our new cephalopod overlords.

Cute thought, but octopuses and squid have some things that hurt them rather badly in that department, as I'd posted on. They are not very good at cooperating, and they can't pass on what they've learned down to future generations.

 

[Angry Floof]

I don't know why they're so smart, but I fully expect to one day welcome our new cephalopod overlords.

Cute thought, but octopuses and squid have some things that hurt them rather badly in that department, as I'd posted on. They are not very good at cooperating, and they can't pass on what they've learned down to future generations.

Give them a little time.

 

[lpetrich]

Are there any freshwater cephalopods? › Ask an Expert (ABC Science) - none are known to exist, and it ought to be easy to catch whatever freshwater ones might exist. That article mentioned a barrier to going from seawater to freshwater: osmotic pressure. Cephalopods never overcame that barrier, though various other animals have, including some clams, some fellow mollusks.

The oceans were plenty salty in the past: Evaporites and the salinity of the ocean during the Phanerozoic: Implications for climate, ocean circulation and life - ScienceDirect


I'll now try to rate elephants, dogs, and cats on this scale.

Morphology:
Manipulative appendages? Elephant: trunk. Dog, Cat: jaws
Dexterity? Elephant: high. Dog, Cat: limited.

Senses:
Vision? Elephant: moderate. Dog, Cat: moderately good
Hearing? Elephant: good. Dog, Cat: very good
Smell? Elephant, Dog, Cat: very good

Ecology:
Lifestyle? Elephant, Dog, Cat: terrestrial
Diet? Elephant: herbivorous. Dog, Cat: carnivorous
Extractive foraging? Elephant: no? Dog (wolf): no? Cat (wild): no?
Predation? Elephant: very limited, Dog (wolf): limited. Cat (wild): medium to high

Social life?
System? Elephant, Dog: groups. Cat: solitary
Long-term bonds? (I'd have to do a lot of research for elephants and wolves/dogs)

Behavioral flexibility?
Find and process food? Elephant: moderate to good. Dog, Cat: good
Social interactions? Elephant, Dog: high. Cat: limited

Life history
Lifespan? Elephant: >40 years. Dog: (wolf) 5-6 years (domestic) 10-13 years. Cat (wild, domestic) 13-14 years.
Parental care of offspring? Elephant, Dog, Cat: present
Reproduction? elephant, Dog, Cat: iteroparity


So elephants and dogs fit the vertebrate high-intelligence profile fairly well, and cats not so well.


My favorite cross-species IQ test is the mirror test: members of what species recognize themselves in mirrors? Or at least act as if they do. A "yes" is for at least one species being known to pass that test. A "no" is for all species tested.

Cephalopods: no. Corvids: yes. Cetaceans: yes. Apes: yes. Elephants: yes. Dogs: no. Cats: no.

 

[steve_bank]

Intelligence manifested by problem solving in new situations is observed in most higher order life. Marine to air brothers.

An octopus given a jar with food inside withholds in the lid so it could sense it figured out how to unscrew the lid.

 

[skepticalbip]

Why are cephalopods so smart?

That seems to be the wrong question. Why implies intent or purpose in its "design".

How they developed their intelligence would seem a more appropriate question. Evolution would select for the more intelligent members among a species of stealth hunters because they would be more successful so more likely to survive to have offspring. Over many, many generations of the more successful (so more intelligent) leaving offspring the average intelligence of the species would increase. OTOH among the filter feeders like oysters there would be no survival advantage for those oysters that were more intelligent than the average.

Given another three or four more million years, the descendants of the octopi may rule the world.

 

[Underseer]

It seems really difficult to estimate intelligence given that they are so distant from us on the phylogenic tree. We know that they are unusually good at solving problems and their brain/body ratio is crazy high, but other than that how do we even tell?

 

[Bronzeage]

It seems really difficult to estimate intelligence given that they are so distant from us on the phylogenic tree. We know that they are unusually good at solving problems and their brain/body ratio is crazy high, but other than that how do we even tell?

What's really weird is lighter colored octopi are more intelligent than darker ones. It's been observed that the octopi that can change color get dumber when placed on a dark background.

I'm trolling somebody who posts on a different forum, who is obsessed with correlation between race and IQ. He insists he is not a racist because he thinks Asians are more intelligent than Caucasians.

It's difficult to assess intelligence in humans and maybe impossible to measure it in animals. Part of the problem is that humans are easily impressed by animals that are good at being animals. For all we know, oysters may have taken set theory to the next level, but all they do is sit there. so we think they're stupid.

 

[lpetrich]

It seems really difficult to estimate intelligence given that they are so distant from us on the phylogenic tree. We know that they are unusually good at solving problems and their brain/body ratio is crazy high, but other than that how do we even tell?

The usual approach is to try to construct comparable sorts of tasks, and that can be challenging. Tests of dexterity, for instance, are tests that most species will do poorly in, because of a lack of good manipulative organs. This applies even to relatively intelligent ones, like dogs and dolphins.

Their phylogeny:

Bilateria

• Protostomia - Lophotrochozoa - Mollusca - Cephalopoda - Coleoida - Octopoda: octopus
• Deuterostomia - Chordata - Vertebrata - Tetrapoda - Amniota
  • Sauropsida - Diapsida - Archosauria - Dinosauria - Theropoda - Avialae - Aves - Neognathae - Neoaves - Passeriformes - Corvidae: crow family
  • Synapsida - Therapsida - Mammalia - Eutheria
    • Afrotheria - Proboscidea - Elephantidae: elephant
    • Boreoeutheria
      • Euarchontoglires - Primates - Simiiformes - Catarrhini - Hominidae: apes, human
      • Laurasiatheria
        • Cetartiodactyla - Cetacea - Odontoceti - Delphinidae: dolphin, orca
        • Carnivora
          • Caniformia - Canidae - Canis lupus: dog
          • Feliformia - Felidae - Felis silvestris: cat

 

[Speakpigeon]

For all we know, oysters may have taken set theory to the next level, but all they do is sit there. so we think they're stupid.

So, you're saying being really smart about set theory doesn't actually mean you know how to protect yourself against being eaten alive at Christmas by a set of ugly idiots?!

I guess I definitely need to do something about that.
EB

 

[Speakpigeon]

We look smart because we can use one tentacle to distract your attention while taking your wallet with another tentacle and all sorts of other things with our other six tentacles.
EB

 

[lpetrich]

Amazing Octopus - Most Intelligent Animal on Earth? 1080p - YouTube -- or at least the most intelligent invertebrate. Octopus or Human Intelligence?| Unedited Movie - Aliens of the Deep Sea | Nature Documentary - YouTube also has that documentary, and both videos seem to have been edited a little bit.

Octopuses are Earthlings, despite having anatomy that is very weird by our standards. Their genomes have been sequenced, and they have lots of familiar kinds of genes in them: The octopus genome and the evolution of cephalopod neural and morphological novelties | Nature


Octopuses are color-blind, seeing only in grayscale, but there is a way for them to have color vision: chromatic aberration, different colors having different focal lengths. That makes some colors more blurred than others, and the animal can then judge color from how the image is blurred at different lens-retina distances. Weird pupils let octopuses see their colorful gardens | Berkeley News Study proposes explanation for how cephalopods see color, despite black and white vision

However, octopuses can see polarization of light: Polarization contrast vision in Octopus. | Journal of Experimental Biology

 

[lpetrich]

I must say that I sometimes envy octopuses' tentacle arms. Wouldn't it be nice to have such wonderfully flexible limbs? Not just that, to have eight of them? But at least I have ten fingers.

Tentacles have evolved several times, notably among cephalopods and cnidarians (sea anemones, jellyfish, etc.). Closer to home, elephant trunks are arguably a kind of tentacle, as are the prehensile tails of some New World monkeys.


​The grim, final days of a mother octopus - UChicago Medicine

In the new study, she used the same California two-spot octopuses to study their odd maternal behaviors. Mature, non-mated females are active predators who spend a lot of time outside their dens and quickly pounce on prey-like fiddler crabs. In the first stage of brooding though, mated females sit with their eggs like a deep-sea hen, stroking them and blowing water over the clutch. For the first three or four days they continue feeding but rarely leave their eggs, snatching the odd unlucky crab only if it happens to get too close.

After four days or so, they stop eating completely. This stage of brooding can last eight to ten more days until they hit the final phase of rapid decline, when things get really ugly. The females become listless, spending more time away from their eggs or slamming themselves against the corners of the tank. They start grooming themselves excessively, running their arms over their mantles until they became a tangled mess. Their skin pales and they lose muscle tone, even beyond what you would expect to see in a starving octopus.

This behavior is controlled by the animal's optic gland, named from being between the eyes. Removing it makes a mother octopus abandon her eggs and act "normal" again. Referring to these glands,

During the non-mated phase when females were actively hunting and eating, they produced high levels of neuropeptides, or small protein molecules used by neurons to communicate with each other that have been linked to feeding behavior in many animals. After mating, these neuropeptides dropped off precipitously.

As the animals began to fast and decline, there was more activity in genes that produce neurotransmitters called catecholamines, steroids that metabolize cholesterol, and insulin-like factors. Wang said finding activity related to metabolism was surprising because it’s the first time the optic gland has been linked to something other than reproduction.

First case of possible iteroparity among coleoid cephalopods: the giant warty squid Kondakovia longimana | Journal of Molluscan Studies | Oxford Academic -- coleoids are octopuses, squid, and their close relatives. The nautilus is the only surviving non-coleoid cephalopod -- and the only surviving shelled cephalopod. Fossils of their shells are abundant in Paleozoic and Mesozoic rocks, but the end-Cretaceous mass extinction was the end for most of them.

 

[untermensche]

So why are they so smart?

Because they developed bigger brains to control appendages and with a bigger brain you can by chance evolve into something with intelligence?

 

[lpetrich]

So why are they so smart?

Because they developed bigger brains to control appendages and with a bigger brain you can by chance evolve into something with intelligence?

This challenging-lifestyle theory is a good theory, I think. It may explain why high intelligence has developed in species that do a lot of sensory processing, like visual perception or echolocation.

 

[untermensche]

A bee has a lot of visual perceptions.

It has extremely complex locomotion in flight.

It controls wings with dexterity and precision.

How does it navigate?

Nobody knows.

That is too complex a brain function for us to understand presently.

What happens in an octopus brain is far more complex.

How bees navigate

https://www.economist.com/babbage/2014/06/12/cognitive-dissonance

 

[rousseau]

Why are cephalopods so smart?

That seems to be the wrong question. Why implies intent or purpose in its "design".

How they developed their intelligence would seem a more appropriate question. Evolution would select for the more intelligent members among a species of stealth hunters because they would be more successful so more likely to survive to have offspring. Over many, many generations of the more successful (so more intelligent) leaving offspring the average intelligence of the species would increase. OTOH among the filter feeders like oysters there would be no survival advantage for those oysters that were more intelligent than the average.

Given another three or four more million years, the descendants of the octopi may rule the world.

Depends. Coming from lpetrich I assume why to mean 'how did these traits evolve' in the animal. But why coming from someone who uses terms like 'evolutionist', sure.

 

[rousseau]

I'd expect 'intelligence' to be a convergent trait, just like anything else: sight, flight etc.

What is the difference between the 'intelligence' of a squirrel and an octopus? They both have a nervous system so you could argue that it's just a matter of degree. In the specific situation of the octopi increased neural capacity became advantageous.

Well why doesn't their intelligence look like the intelligence of humans? Why should it? Their nervous system adapts to their ecological environment.

Doesn't quite answer the question of how that came to be, except in the most general way: the disadvantage of a bigger brain was out-weighed by the advantage of the brain's capacity.