5 Animal Species With Surprising Memories

A repost of an original article from The Scorpion and the Frog.

We often think of animals as having hilariously short memories – the “memory of a goldfish”, if you will. But many animals have memories that can put yours to shame.

There are many different kinds of memory and each of them is controlled differently by different parts of the brain. Short-term memory can be thought of as the brain’s scratch pad: It holds a small amount of information for a short period of time while your brain decides whether it is worth retaining in long-term memory or if it can just fade away. When a short-term memory becomes a long-term memory, this process is called consolidation and involves physiological changes in the brain.

Long-term memory can be further divided into two main types: procedural memory and declarative memory. Procedural memory is used to remember how to do things and what objects are needed to do those things. Declarative memory is used for recall and can be further divided into memory used to recall facts (semantic memory) and events (episodic memory).Each of these different types of memories are stored in different parts of the brain. Furthermore, different types of facts (remembering faces versus numbers, for example) and different types of events (depending on if they have an emotional component or not, for example) are also stored in the brain differently. Because species differ in how we rely on our brains, it makes sense that this might be reflected in our abilities to remember in different ways.

So let’s check out some of the most amazing memories in the animal kingdom:

Do you know what all your kids and nieces and nephews are
doing right now? These elephants do. Photo by PJ KAPDostie
at Wikimedia.

1) They say an elephant never forgets. Elephants are very social animals that live in large stable herds. This has led to some incredible feats of social memory. They can keep track of the whereabouts of 30 group members at once and they can remember an animal they briefly met over 20 years ago. For an animal that lives about 50 or 60 years, this is very impressive. Elephants also have outstanding episodic memory: In 1993, Tarangire National Park in Tanzania suffered the worst drought that it had seen in 35 years. It was so severe that it killed 20% of elephant calves, compared to the average loss of about 2%. Of three herds that lived in the park in 1993, two of them were led by females that had lived during the severe droughts of 1958-61 and those herds left the park and were more successful at finding food and water. The herd that stayed was led by a younger female that had never experienced such a severe drought and that herd suffered 63% of the total mortality.

Dolphins never forget a name. Photo from the
NOAA Photo Library available at Wikimedia.

2) Bottlenose dolphins have even more incredible social memories. They, like elephants, live in complex social groups. Each dolphin has a unique whistle that it uses like a name. When they are played recordings of whistles of companions they lived with years or even decades earlier, they approach the speakers for longer than when they are played the whistles of dolphins they never met. The fact that they, like elephants, remember companions for over 20 years is much more impressive because their lifespan is only 40-50 years!

Sea lions can remember
meaningless tricks for years.
Photo by LSA2886 at Wikimedia.

3) Sea lions have amazing procedural memory. In 1991, marine biologists at the University of California, Santa Cruz, taught a California sea lion named Rio a card trick. They held up one card with a letter or number on it and another set of two cards: one that matched the first card and one that did not. Rio learned to pick the matching card to be rewarded with a fish. Everyone was impressed and she didn't do the trick again... until 10 years later, when researchers pulled out the cards and asked her to do it again. Rio had the same score in 2001 with no practice that she did in 1991 when she originally learned the trick!

Clark's nutcrackers can remember where they stashed
30,000 pine nuts.I can't even keep track of my keys.
Photo by Gunnsteinn Jonsson at Wikimedia.

4) Clark’s nutcrackers can remember the exact location of 30,000 pine nuts. This kind of superhero ability is born out of necessity: nutcrackers completely rely on their caches of food to get them through the winter. However, despite their amazing long-term spatial memory, their short-term memory is below average: they can’t even remember the color of a light for 30 seconds.

5) Chimpanzees can put your working memory to shame. Working memory is a form of short-term memory that is applied to a task. A group of researchers taught chimpanzees to do a task in which they were shown the numbers from 1-9 in random locations on a computer screen. When the numbers are covered, chimps can remember where each number was. Furthermore, they only need to see these randomly placed number for a few seconds to get this task correct. In comparison, only people that are considered savants have comparable abilities.

Nature Shapes Faithful and Unfaithful Brains

A reposting of an original article from January 22, 2017.

Among monogamous animals, some individuals are more faithful than others. Could these differences in fidelity be, in part, because of differences in our brains? And if so, why does this diversity in brain and behavior exist?

A snuggly prairie vole family. Photo from theNerdPatrol at Wikimedia Commons.

Prairie voles are small North American rodents that form monogamous pair bonds, share parental duties, and defend their homes. Although prairie voles form monogamous pairs, that does not mean they are sexually exclusive. About a quarter of prairie vole pups are conceived outside of their parents’ union.

Not all male prairie voles cheat on their partners at the same rates. In fact, some males are very sexually faithful. It turns out, there are both costs and benefits to being faithful and to cheating. Mariam Okhovat, Alejandro Berrio, Gerard Wallace, and Steve Phelps from the University of Texas at Austin, and Alex Ophir from Cornell University used radio-telemetry to track male prairie voles for several weeks to explore what some of these costs and benefits might be. Compared to males that only sired offspring with their own partner, unfaithful males had larger home ranges, intruded on more territories of other individuals, and encountered females more often. However, these unfaithful males were also more likely to be cheated on when they were away (probably because they were away more). I guess even rodents live by The Golden Rule.

Maps of how paired male voles in this study used space. The solid red/orange/yellow peaks show where a faithful male (in the left map) and unfaithful male (in the right map) spent their time in relation to where other paired males spent their time (showed by open blue peaks). Image from the Okhovat et al. Science paper (2015).

Vasopressin is a hormone that has been found to affect social behaviors such as aggression and pair bonding when it acts in the brain. Mariam, Alejandro, Gerard, Alex, and Steve all set out to determine how vasopressin in the brain may relate to sexual fidelity in prairie voles. They found that faithful males had lots of a particular type of vasopressin receptor (called V1aR) in certain brain areas involved in spatial memory. Surprisingly, faithful males did not have more V1aR in brain regions typically associated with pair bonding and aggression. A male that has more V1aR in spatial memory regions might better remember where his own mate is and where other males have been aggressive, which would decrease the chances that he would intrude on other territories in search of other females and increase the time that he spends home with his own mate. A male that has less V1aR in spatial memory regions might be less likely to learn from his negative experiences and more likely to sleep around.

Photos of a brain section from a faithful male (left) and unfaithful male (right). The dark shading shows the density of V1aR vasopressin receptors. The arrows show the location of the retrosplenial cortex (RSC), a brain area involved in spatial memory. Faithful males had significantly more V1aR receptors in the RSC compared to unfaithful males. Image from the Okhovat et al. Science paper (2015).

The research team then found genotype variations that related to having lots or not much V1aR in one of these spatial memory regions (called retrosplenial cortex … but we’ll just call it RSC). They confirmed these findings with a breeding study, in which they reared siblings that were genetically similar, but some had the genotype they predicted would result in lots of V1aR in RSC and some had the genotype they predicted would result in very little V1aR in RSC. They confirmed that these genetic variations correspond with the amount of vasopressin receptor in this specific spatial memory area.

The researchers then looked closer at the different versions of this vasopressin receptor gene in the RSC brain region to see if differences in the amount of vasopressin receptors in RSC may be caused by the epigenetic state of the gene (i.e. how active the gene is). They found that the genotype that results in very little V1aR in RSC had many more potential methylation sites, which can repress gene activity.

All of this data together tells a very interesting story. Male prairie voles that have the genotype for more V1aR vasopressin receptors in their RSC part of their brain are more likely to remember where their home and mate are and to remember where other aggressive prairie voles are, which will make them more likely to spend more time with their partner, to be sexually faithful and to have sexually faithful partners. Male prairie voles that have the genotype for less V1aR in their RSC are more likely to forget where their home and mate are and where other aggressive prairie voles are, which will make them more likely to cheat and to be cheated on. Overall, faithful and unfaithful male prairie voles have roughly the same number of offspring, but advantages may emerge with changes in population density. Prairie vole populations vary anywhere from 25 to 600 voles per hectare from year to year. When population densities are high, you (and your partner) are more likely to encounter more potential mates and it may benefit you to cheat (and have a “cheater’s brain”). When population densities are low, you (and your partner) are less likely to encounter more potential mates and it may benefit you to be faithful (and have a “faithful brain”). But when populations fluctuate between high and low densities, both faithful and unfaithful genotypes will get passed along from generation to generation.


Want to know more? Check this out:

Okhovat, M., Berrio, A., Wallace, G., Ophir, A., & Phelps, S. (2015). Sexual fidelity trade-offs promote regulatory variation in the prairie vole brain Science, 350 (6266), 1371-1374 DOI: 10.1126/science.aac5791

Mind-Manipulating Slave-Making Ants!

A reposting of an article from October 10, 2012.

An entire colony enslaved by an alien species to care for their young. Slave rebellions quelled by mind manipulation. It sounds like science fiction, right? But it really happens!

Myrmoxenus ravouxi (called M. ravouxi for “short”) is a slave-making ant species in which the queen probably wears a chemical mask, matching the scent of a host species in order to invade their nest without detection. Once inside, she lays her eggs for the host species workers to care for. Armies of M. ravouxi workers then raid these host colonies to steel their brood to become future slave-laborers to serve the needs of the M. ravouxi colony.

A M. ravouxi queen throttling a host queen. Photo by Olivier Delattre.

Enslaved worker ants could rebel: They could destroy the parasite brood or at least not do a good job caring for them. But to selectively harm the parasite brood without harming their own nests’ brood, the host ants would have to be able to tell them apart. Ants learn the smell of their colony in their youth, so any ants born to an already-parasitized colony would likely not be able to tell apart parasite ants from their own species. But what about ants that were born to colonies before they were invaded?

Olivier Delattre, Nicolas Châline, Stéphane Chameron, Emmanuel Lecoutey, and Pierre Jaisson from the Laboratory of Experimental Ethology in France figured that compared to ant species that were never hosts to M. ravouxi colonies, ant species that were commonly hosts of M. ravouxi colonies would be better able to discriminate their own species’ brood from M. ravouxi brood. Host species may even be better at discriminating in general.

The researchers collected ant colonies from near Fontainebleau and Montpellier in France. They collected M. ravouxi colonies and colonies of a species that they commonly parasitize (but were not parasitized at the time): Temnothorax unifasciatus (called T. unifasciatus for “short”). The researchers also collected T. unifasciatus that were parasitized by M. ravouxi at the time. Additionally, they collected colonies of T. nylanderi and T. parvulus, two species that are never parasitized by M. ravouxi. (Sorry guys. All these species go by their scientific names. But really, that just makes them sound all the more mysterious, right?). The researchers took all their ant colonies back to the lab and housed them in specialized plastic boxes (i.e. scientific ant-farms).

On the day of the tests, the scientists removed a single pupa (kind of like an ant-toddler) from one nest and placed it into a different nest of the same species or back in its own nest. They did this for colonies of both non-host species and for colonies of host species T. unifasciatus that were not parasitized at the time. Then they counted how many times the workers bit the pupa (an aggressive behavior) or groomed the pupa (a caring behavior).

Workers from all three species bit the pupa that was not from their colony more than they bit their own colony’s pupa. But the T. unifasciatus (the host species) were even more aggressive to foreign pupa than the other species. And only the T. unifasciatus withheld grooming from the pupa that was not from their colony compared to the one that was from their colony. Although all three species seemed to be able to tell the difference between a pupa from their own nest versus one from another nest, only the species that is regularly enslaved by M. ravouxi decreased care to foreign young. So that is what these ants do when they are not enslaved. How do you think enslaved ants respond to their own species’ young compared to M. ravouxi young?

A 1975 cover of Galaxie/Bis, a French science
fiction magazine, by Philippe Legendre-Kvater.
Image from Wikimedia.

The researchers repeated the study using enslaved T. unifasciatus, placing either a pupa of their own species from a different nest or a M. ravouxi pupa in with their brood. Even though prior to M. ravouxi takeover the T. unifasciatus bit foreign pupa more than their own, after M. ravouxi takeover they didn’t bite foreign pupa of their own species or M. ravouxi pupa very much. Not only that, but they groomed the M. ravouxi pupa more than the pupa of their own species! Ah hah! Mind control!

This, my friends, is the kind of truth that science fiction is made from.

But how might this work? Ants born to an enslaved colony would be exposed to both their own odors and the M. ravouxi odors. Because ants learn the smell of their colony in the first few days after they emerge from their eggs, these enslaved ants would have a broader set of smells that they may perceive as being “within the family”. That would explain why the enslaved T. unifasciatus ants didn’t attack either the foreign-born T. unifasciatus or the M. ravouxi young, but it doesn’t explain why the enslaved ants provided more care to the M. ravouxi than they did to their own species. One possibility is that the M. ravouxi produce more or especially attractive odors to encourage the host workers to take care of them.

There is still more to learn about this system: How exactly may the M. ravouxi be hijacking the pheromonal systems of their host species? How are the host species protecting themselves from exploitation? I guess we’ll have to wait for the sequel.

Want to know more? Check this out:

Delattre, O., Chȃline, N., Chameron, S., Lecoutey, E., & Jaisson, P. (2012). Social parasite pressure affects brood discrimination of host species in Temnothorax ants Animal Behaviour, 84, 445-450 DOI: 10.1016/j.anbehav.2012.05.020

Nature Shapes Faithful and Unfaithful Brains

Among monogamous animals, some individuals are more faithful than others. Could these differences in fidelity be, in part, because of differences in our brains? And if so, why does this diversity in brain and behavior exist?

A snuggly prairie vole family. Photo from theNerdPatrol at Wikimedia Commons.

Prairie voles are small North American rodents that form monogamous pair bonds, share parental duties, and defend their homes. Although prairie voles form monogamous pairs, that does not mean they are sexually exclusive. About a quarter of prairie vole pups are conceived outside of their parents’ union.

Not all male prairie voles cheat on their partners at the same rates. In fact, some males are very sexually faithful. It turns out, there are both costs and benefits to being faithful and to cheating. Mariam Okhovat, Alejandro Berrio, Gerard Wallace, and Steve Phelps from the University of Texas at Austin, and Alex Ophir from Cornell University used radio-telemetry to track male prairie voles for several weeks to explore what some of these costs and benefits might be. Compared to males that only sired offspring with their own partner, unfaithful males had larger home ranges, intruded on more territories of other individuals, and encountered females more often. However, these unfaithful males were also more likely to be cheated on when they were away (probably because they were away more). I guess even rodents live by The Golden Rule.

Maps of how paired male voles in this study used space. The solid red/orange/yellow peaks show where a faithful male (in the left map) and unfaithful male (in the right map) spent their time in relation to where other paired males spent their time (showed by open blue peaks). Image from the Okhovat et al. Science paper (2015).

Vasopressin is a hormone that has been found to affect social behaviors such as aggression and pair bonding when it acts in the brain. Mariam, Alejandro, Gerard, Alex, and Steve all set out to determine how vasopressin in the brain may relate to sexual fidelity in prairie voles. They found that faithful males had lots of a particular type of vasopressin receptor (called V1aR) in certain brain areas involved in spatial memory. Surprisingly, faithful males did not have more V1aR in brain regions typically associated with pair bonding and aggression. A male that has more V1aR in spatial memory regions might better remember where his own mate is and where other males have been aggressive, which would decrease the chances that he would intrude on other territories in search of other females and increase the time that he spends home with his own mate. A male that has less V1aR in spatial memory regions might be less likely to learn from his negative experiences and more likely to sleep around.

Photos of a brain section from a faithful male (left) and unfaithful male (right). The dark shading shows the density of V1aR vasopressin receptors. The arrows show the location of the retrosplenial cortex (RSC), a brain area involved in spatial memory. Faithful males had significantly more V1aR receptors in the RSC compared to unfaithful males. Image from the Okhovat et al. Science paper (2015).

The research team then found genotype variations that related to having lots or not much V1aR in one of these spatial memory regions (called retrosplenial cortex … but we’ll just call it RSC). They confirmed these findings with a breeding study, in which they reared siblings that were genetically similar, but some had the genotype they predicted would result in lots of V1aR in RSC and some had the genotype they predicted would result in very little V1aR in RSC. They confirmed that these genetic variations correspond with the amount of vasopressin receptor in this specific spatial memory area.

The researchers then looked closer at the different versions of this vasopressin receptor gene in the RSC brain region to see if differences in the amount of vasopressin receptors in RSC may be caused by the epigenetic state of the gene (i.e. how active the gene is). They found that the genotype that results in very little V1aR in RSC had many more potential methylation sites, which can repress gene activity.

All of this data together tells a very interesting story. Male prairie voles that have the genotype for more V1aR vasopressin receptors in their RSC part of their brain are more likely to remember where their home and mate are and to remember where other aggressive prairie voles are, which will make them more likely to spend more time with their partner, to be sexually faithful and to have sexually faithful partners. Male prairie voles that have the genotype for less V1aR in their RSC are more likely to forget where their home and mate are and where other aggressive prairie voles are, which will make them more likely to cheat and to be cheated on. Overall, faithful and unfaithful male prairie voles have roughly the same number of offspring, but advantages may emerge with changes in population density. Prairie vole populations vary anywhere from 25 to 600 voles per hectare from year to year. When population densities are high, you (and your partner) are more likely to encounter more potential mates and it may benefit you to cheat (and have a “cheater’s brain”). When population densities are low, you (and your partner) are less likely to encounter more potential mates and it may benefit you to be faithful (and have a “faithful brain”). But when populations fluctuate between high and low densities, both faithful and unfaithful genotypes will get passed along from generation to generation.


Want to know more? Check this out:

Okhovat, M., Berrio, A., Wallace, G., Ophir, A., & Phelps, S. (2015). Sexual fidelity trade-offs promote regulatory variation in the prairie vole brain Science, 350 (6266), 1371-1374 DOI: 10.1126/science.aac5791

Cow Pies Can Make You Smarter and Less Stressed

A reposting of an article from August, 2015

It seems like everyone is running around buying school supplies and books, registering for classes, and fretting about how hard it is going to be to learn another whole year’s worth of stuff. The secret to success, it turns out, may lie in cow dung.

A cow pie. Photo taken by Jeff Vanuga at
the USDA available at Wikimedia Commons.

Recent research has highlighted the important role that microbes living in animal digestive tracts have on host animals’ health and behavior. This influence of our gut microbes on our behavior is called the microbiota-gut-brain axis. Many of these microbes have long-standing populations that reproduce and spend their whole lives in our guts. Because our digestive tracts do not have much oxygen, these species are anaerobic (do not require oxygen to live). However, our gut communities also have more transient aerobic members (species that do require oxygen to live) that come in when they are ingested and die or leave with the droppings. One of these transient aerobic intestinal citizens is Mycobacterium vaccae (or M. vaccae for short), an aerobic bacterium that naturally lives in soil, water, and yes, cow dung.

When mice are injected with heat-killed M. vaccae, they develop an immune response that activates their brain serotonin system and reduces signs of stress. Serotonin is a neurotransmitter that is found in the brain and is involved in regulating alertness, mood, learning and memory. In fact, many antidepressant drugs work by increasing the amount of available serotonin in the brain. Interestingly, serotonin is also found in the digestive system, where it plays a role in digestive health. Since M. vaccae can increase serotonin function, and serotonin reduces anxiety and improves learning, researchers Dorothy Matthews and Susan Jenks at The Sage Colleges in New York set out to test whether eating live M. vaccae could reduce anxiety and improve learning in mice.

A drawing of the mouse maze used by Dorothy and Susan.
This image is from their 2013 Behavioural Processes paper.

The researchers developed a Plexiglas mouse-maze with three difficulty levels, where each increase in difficulty was marked by more turns and a longer path. They encouraged the mice to run the maze by placing a tasty treat (a square of peanut butter on Wonder Bread™) at the end of the maze. Half of the mice were given live M. vaccae on the peanut butter and bread treat three weeks and one week before running the maze, and then again on each treat at the end of each maze run. The other half were given peanut butter and bread without the bacterial additive. The mice then ran the maze roughly every other day: four times at level 1, four times at level 2 and four times at level 3. Each maze run was video recorded and the researchers later watched the videos to count stress-related behaviors.

The mice that ingested M. vaccae on their peanut butter sandwiches completed the maze twice as fast as those that ate plain peanut butter sandwiches. They also had fewer stress-related behaviors, particularly at the first difficulty level of the maze when everything was new and scary. In general, the fewer stress behaviors a mouse did, the faster its maze-running time was. The mice that ate the M. vaccae also tended to make fewer mistakes.

The researchers then wanted to know how long the effects of M. vaccae lasted. They continued to test the mice in the same maze, again with four runs at level 1, four runs at level 2 and four runs at level 3, but for these maze runs no one was given the M. vaccae. The mice that had previously eaten the M. vaccae continued to complete the maze faster and with fewer mistakes and to show fewer stress-related behaviors for about the first week before the M. vaccae effects wore off.

What does this all mean? It means eating dirt isn’t all bad (although I don't recommend eating cow poop). Letting yourself get a bit dirty and ingesting some of nature's microbes could even help you learn better, remember more, and stay calm - especially in new situations. Just something to think about as the school year gets started.


Want to know more? Check these out:

1. Matthews, D., & Jenks, S. (2013). Ingestion of Mycobacterium vaccae decreases anxiety-related behavior and improves learning in mice Behavioural Processes, 96, 27-35 DOI: 10.1016/j.beproc.2013.02.007

2. Lowry, C., Hollis, J., de Vries, A., Pan, B., Brunet, L., Hunt, J., Paton, J., van Kampen, E., Knight, D., Evans, A., Rook, G., & Lightman, S. (2007). Identification of an immune-responsive mesolimbocortical serotonergic system: Potential role in regulation of emotional behavior Neuroscience, 146 (2), 756-772 DOI: 10.1016/j.neuroscience.2007.01.067

Why Are Cats Scared of Cucumbers?

Have you seen the video of cats’ terrified responses to cucumbers? No?! Then check this out:

This hilarious video has led many people to try this on their own cats… to varying degrees of success. And it has led to some curious questions: Why are these cats so terrified of a cucumber? And why isn’t my cat?

The fear of something specific (like a cucumber) can either be innate (as in, you’re born with it) or learned. For many animal species, it would make sense to be born with a natural fear of something that can kill you the first time you encounter it, like a steep drop, being submerged under water, or a venomous snake. Some of these things can be so dangerous that an animal with a fear of anything that even resembles it may have a higher chance of surviving long enough to produce its own fearful babies some day. So maybe these cats have an innate fear of snakes that has caused them to respond in this hilarious way to anything that resembles a snake… like a cucumber?

But if cats have an innate fear of snakes, why don’t they all respond to cucumbers this way?

Sometimes fears appear to be innate, when they are actually learned. For example, in 2009, researchers Judy DeLoache and Vanessa LoBue at the University of Virginia explored whether the fear of snakes is innate in human babies with a series of three experiments.

In the first experiment, Judy and Vanessa showed 9- and 10-month old babies silent films of snakes and other animals and they measured how long the babies looked at each type of film. Presumably, a baby will be more vigilant of and spend more time looking at something they are scared of. They found that the babies responded exactly the same towards the snake films than to the films of other animals.

Next, the experimenters showed the babies the films of either a snake or another animal again. However, this time they played the audio of a person sounding either happy or frightened along with the video. The babies looked at the non-snake animal videos the same amount regardless of whether the audio sounded happy or scared. However, the babies looked at the snake videos longer if the audio sounded scared than if the audio sounded happy.

In the third experiment, the experimenters repeated this pairing of audio with visuals, but this time they used still pictures of snakes and non-snake animals instead of videos. This time, the babies did not react differently to the snake or non-snake animal pictures depending on if the audio sounded happy or scared.

This shows that, at least for people, we don’t have an innate fear of snakes, but we do have an innate tendency to develop a fear of snakes if we are exposed to the right combination of hearing someone being afraid and seeing a moving snake. In other words, some fears are more contagious than others. And this isn’t just true for people: a study of rhesus monkeys found that baby monkeys raised by parents that were afraid of snakes only developed a fear of snakes themselves if they observed their parents acting fearful in the presence of a real or toy snake. So perhaps, the cats in this cucumber video saw or heard someone being fearful of something cucumber-like (or snake-like) when they were young... Or maybe they were just surprised by something sneaking up on them while they were eating.

In any case, don’t be too bummed if this hasn’t worked on your cat… Maybe try it on your friends instead!

Want to know more? Check these out:

DeLoache, J., & LoBue, V. (2009). The narrow fellow in the grass: human infants associate snakes and fear Developmental Science, 12 (1), 201-207 DOI: 10.1111/j.1467-7687.2008.00753.x

Mineka, S., Davidson, M., Cook, M., & Keir, R. (1984). Observational conditioning of snake fear in rhesus monkeys. Journal of Abnormal Psychology, 93 (4), 355-372 DOI: 10.1037/0021-843X.93.4.355

Caught in My Web: The Intelligence and Creativity of Crows, Octopuses, Monkeys, Fish and Dogs

Image by Luc Viatour at Wikimedia.

For this edition of Caught in My Web, we marvel at animal intelligence.

1. Joshua Klein talks about crow intelligence and their potential for training in this fun TED talk.

2. Jason Goldman at io9 explains an amazing discovery that Atlantic cod can also innovate to solve problems.

3. Sarah Williams at Science explains research out of Harvard that shows that untrained rhesus monkeys can do math and we can use this to learn about how we think.

4. A veined octopus shows off his imagination as he creates a “hiding” place:

5. And last, but not least, three shelter dogs were taught to drive! Here are the results:

5 Animal Species With Surprising Memories

We often think of animals as having hilariously short memories – the “memory of a goldfish”, if you will. But many animals have memories that can put yours to shame.

There are many different kinds of memory and each of them is controlled differently by different parts of the brain. Short-term memory can be thought of as the brain’s scratch pad: It holds a small amount of information for a short period of time while your brain decides whether it is worth retaining in long-term memory or if it can just fade away. When a short-term memory becomes a long-term memory, this process is called consolidation and involves physiological changes in the brain.

Long-term memory can be further divided into two main types: procedural memory and declarative memory. Procedural memory is used to remember how to do things and what objects are needed to do those things. Declarative memory is used for recall and can be further divided into memory used to recall facts (semantic memory) and events (episodic memory).Each of these different types of memories are stored in different parts of the brain. Furthermore, different types of facts (remembering faces versus numbers, for example) and different types of events (depending on if they have an emotional component or not, for example) are also stored in the brain differently. Because species differ in how we rely on our brains, it makes sense that this might be reflected in our abilities to remember in different ways.

So let’s check out some of the most amazing memories in the animal kingdom:

Do you know what all your kids and nieces and nephews are
doing right now? These elephants do. Photo by PJ KAPDostie
at Wikimedia.

1) They say an elephant never forgets. Elephants are very social animals that live in large stable herds. This has led to some incredible feats of social memory. They can keep track of the whereabouts of 30 group members at once and they can remember an animal they briefly met over 20 years ago. For an animal that lives about 50 or 60 years, this is very impressive. Elephants also have outstanding episodic memory: In 1993, Tarangire National Park in Tanzania suffered the worst drought that it had seen in 35 years. It was so severe that it killed 20% of elephant calves, compared to the average loss of about 2%. Of three herds that lived in the park in 1993, two of them were led by females that had lived during the severe droughts of 1958-61 and those herds left the park and were more successful at finding food and water. The herd that stayed was led by a younger female that had never experienced such a severe drought and that herd suffered 63% of the total mortality.

Dolphins never forget a name. Photo from the
NOAA Photo Library available at Wikimedia.

2) Bottlenose dolphins have even more incredible social memories. They, like elephants, live in complex social groups. Each dolphin has a unique whistle that it uses like a name. When they are played recordings of whistles of companions they lived with years or even decades earlier, they approach the speakers for longer than when they are played the whistles of dolphins they never met. The fact that they, like elephants, remember companions for over 20 years is much more impressive because their lifespan is only 40-50 years!

Sea lions can remember
meaningless tricks for years.
Photo by LSA2886 at Wikimedia.

3) Sea lions have amazing procedural memory. In 1991, marine biologists at the University of California, Santa Cruz, taught a California sea lion named Rio a card trick. They held up one card with a letter or number on it and another set of two cards: one that matched the first card and one that did not. Rio learned to pick the matching card to be rewarded with a fish. Everyone was impressed and she didn't do the trick again... until 10 years later, when researchers pulled out the cards and asked her to do it again. Rio had the same score in 2001 with no practice that she did in 1991 when she originally learned the trick!

Clark's nutcrackers can remember where they stashed
30,000 pine nuts.I can't even keep track of my keys.
Photo by Gunnsteinn Jonsson at Wikimedia.

4) Clark’s nutcrackers can remember the exact location of 30,000 pine nuts. This kind of superhero ability is born out of necessity: nutcrackers completely rely on their caches of food to get them through the winter. However, despite their amazing long-term spatial memory, their short-term memory is below average: they can’t even remember the color of a light for 30 seconds.

5) Chimpanzees can put your working memory to shame. Working memory is a form of short-term memory that is applied to a task. A group of researchers taught chimpanzees to do a task in which they were shown the numbers from 1-9 in random locations on a computer screen. When the numbers are covered, chimps can remember where each number was. Furthermore, they only need to see these randomly placed number for a few seconds to get this task correct. In comparison, only people that are considered savants have comparable abilities.

Cow Pies Can Make You Smarter and Less Stressed

It seems like everyone is running around buying school supplies and books, registering for classes, and fretting about how hard it is going to be to learn another whole year’s worth of stuff. The secret to success, it turns out, may lie in cow dung.

A cow pie. Photo taken by Jeff Vanuga at
the USDA available at Wikimedia Commons.

Recent research has highlighted the important role that microbes living in animal digestive tracts have on host animals’ health and behavior. This influence of our gut microbes on our behavior is called the microbiota-gut-brain axis. Many of these microbes have long-standing populations that reproduce and spend their whole lives in our guts. Because our digestive tracts do not have much oxygen, these species are anaerobic (do not require oxygen to live). However, our gut communities also have more transient aerobic members (species that do require oxygen to live) that come in when they are ingested and die or leave with the droppings. One of these transient aerobic intestinal citizens is Mycobacterium vaccae (or M. vaccae for short), an aerobic bacterium that naturally lives in soil, water, and yes, cow dung.

When mice are injected with heat-killed M. vaccae, they develop an immune response that activates their brain serotonin system and reduces signs of stress. Serotonin is a neurotransmitter that is found in the brain and is involved in regulating alertness, mood, learning and memory. In fact, many antidepressant drugs work by increasing the amount of available serotonin in the brain. Interestingly, serotonin is also found in the digestive system, where it plays a role in digestive health. Since M. vaccae can increase serotonin function, and serotonin reduces anxiety and improves learning, researchers Dorothy Matthews and Susan Jenks at The Sage Colleges in New York set out to test whether eating live M. vaccae could reduce anxiety and improve learning in mice.

A drawing of the mouse maze used by Dorothy and Susan.
This image is from their 2013 Behavioural Processes paper.

The researchers developed a Plexiglas mouse-maze with three difficulty levels, where each increase in difficulty was marked by more turns and a longer path. They encouraged the mice to run the maze by placing a tasty treat (a square of peanut butter on Wonder Bread™) at the end of the maze. Half of the mice were given live M. vaccae on the peanut butter and bread treat three weeks and one week before running the maze, and then again on each treat at the end of each maze run. The other half were given peanut butter and bread without the bacterial additive. The mice then ran the maze roughly every other day: four times at level 1, four times at level 2 and four times at level 3. Each maze run was video recorded and the researchers later watched the videos to count stress-related behaviors.

The mice that ingested M. vaccae on their peanut butter sandwiches completed the maze twice as fast as those that ate plain peanut butter sandwiches. They also had fewer stress-related behaviors, particularly at the first difficulty level of the maze when everything was new and scary. In general, the fewer stress behaviors a mouse did, the faster its maze-running time was. The mice that ate the M. vaccae also tended to make fewer mistakes.

The researchers then wanted to know how long the effects of M. vaccae lasted. They continued to test the mice in the same maze, again with four runs at level 1, four runs at level 2 and four runs at level 3, but for these maze runs no one was given the M. vaccae. The mice that had previously eaten the M. vaccae continued to complete the maze faster and with fewer mistakes and to show fewer stress-related behaviors for about the first week before the M. vaccae effects wore off.

What does this all mean? It means eating dirt isn’t all bad (although I don't recommend eating cow poop). Letting yourself get a bit dirty and ingesting some of nature's microbes could even help you learn better, remember more, and stay calm - especially in new situations. Just something to think about as the school year gets started.

Want to know more? Check these out:

1. Matthews, D., & Jenks, S. (2013). Ingestion of Mycobacterium vaccae decreases anxiety-related behavior and improves learning in mice Behavioural Processes, 96, 27-35 DOI: 10.1016/j.beproc.2013.02.007

2. Lowry, C., Hollis, J., de Vries, A., Pan, B., Brunet, L., Hunt, J., Paton, J., van Kampen, E., Knight, D., Evans, A., Rook, G., & Lightman, S. (2007). Identification of an immune-responsive mesolimbocortical serotonergic system: Potential role in regulation of emotional behavior Neuroscience, 146 (2), 756-772 DOI: 10.1016/j.neuroscience.2007.01.067

The Weirdest Animals on Earth: 12 Amazing Facts About Octopuses



Photo of a day octopus by
Ahmed Abdul Rahman available
at Wikimedia Commons.

1. The plural of octopus is octopuses. How an English word is pluralized depends, in part, on its origins. Latin words that end in –us are generally pluralized by replacing the –us with an –i (the plural of alumnus, for example, is alumni). But octopus is not Latin – It comes from the ancient Greek word októpous, whose plural is októpodes. Although octopodes is technically correct, since it has been adopted into the English language, the word is now pluralized in the English way, making it octopuses. So octopi is commonly used but not technically correct, octopodes is technically correct but not commonly used and octopussies is just plain wrong.

2. Octopuses are mollusks. This means that they are not only closely related to squid and cuttlefish, but also to clams, oysters, snails and slugs.

3. Octopuses are crazy-smart. They can solve problems, learn from watching others, use tools, and remember experiences. They even have personalities and play with toys. Check this out:

4. Octopuses have nine brains! Rather than a large centralized brain like ours, octopus brains are more like the internet. Their main CPU is a fairly small brain in their head, but each of their eight arms has an additional brain of its own. In fact, two-thirds of an octopus’ neurons are in the arms, which can independently attach to things, push things, and even smell things. They can even react after they have been severed! Not only that, but their severed arms recognize their previous owner:

5. If an octopus loses an arm, it can grow back. Those crazy arms are like the brooms in Disney's Sorcerer's Apprentice in Fantasia!

6. Octopuses are amazing camouflage artists. Their soft bodies can squeeze into ridiculously small cracks and crevices and take on any number of shapes. A 50-pound octopus, for example, can squeeze through a 2-inch hole! They can also change the color and texture of their skin to match their background.

The mimic octopus, the ultimate master of disguise, doesn’t just imitate their background, but also flounders, starfish, poisonous lionfish, and sea snakes.



A vertebrate eye (left) versus an octopus eye (right).
1: Retina, 2: Nerve fibers, 3: Optic nerve, 4: Blind spot.
Image by Jerry Crimson Mann at Wikimedia.

7. Octopuses don’t have visual blind-spots. Most animal eyes detect light patterns when light travels to the retina (the layer in the back of the eye) and falls on photoreceptor cells, causing the cells to send electrical signals through the optic nerve to the brain. Vertebrate photoreceptor cells face backwards, so their nerve fibers come in front of the retina and then exit the eye together through the optic nerve, creating a small region in the back of the eye with no photoreceptor cells. If light falls on this spot, we literally will not see it, although our brain will compensate for this missing light by imagining what should be there based on the rest of what we see. We call this our blind spot. You can test your blind spot by closing your left eye and focusing your right eye on the “R” below. Move your face towards or away from the screen until the “L” disappears. You can test your left eye by staring at the “L” in the same way.

In octopus eyes, the photoreceptor cells face forwards and the nerve fibers go behind the retina. This means that they have a continuous layer of photoreceptor cells and no blind spot.

8. Octopuses are more blue blooded than police officers. Their blood is truly blue, due to the fact that they don’t have hemoglobin, our respiratory pigment that contains iron and turns red when it binds to oxygen. Rather, they have hemocyanin, which contains copper and turns blue when oxygen binds to it.

9. Octopuses have three hearts! They have two small hearts that each pump blood through the gills and a main systemic heart that collects the blood and pumps it through the circulatory system.

10. Octopus ink is a defensive chemical concoction. It not only obscures the view of an attacker, but it also contains a chemical that irritates the predator’s eyes and temporarily paralyzes its sense of smell.

11. Octopuses bite with a bird-like beak and venomous saliva, which is mostly used to subdue prey. Of the approximately 300 octopus species, only the small blue-ringed octopus is known to be deadly to humans.

12. Octopuses die after they mate for the first time. And they mate in an odd way too: males use the tip of their third arm on the right to either insert their spermatophores (sperm packets) directly into the female’s tubular breathing funnel or he just hands it to her (The tip of the third right arm can be used to tell if an octopus is male or female). If he hands it to her, she accepts it with one of her right arms (we don’t know why they’re right-handed this way). Then the males go off to die. The females eventually lay up to 400,000 fertilized eggs, although they can wait months before they do this. She tends them and guards them at the exclusion of all else until they hatch, at which point her body rapidly deteriorates as her cells die off.

Song Battles With Other Species Can Change Your Tune

Many animals defend territories from members of their own species for mating, breeding, and finding food and they often use species-specific vocalizations to do this. Defending a territory can be risky and costly in both energy and time, so even territorial animals generally don’t waste this effort on other species that do not share their same food and breeding needs. But what do you do if you live around another very similar species that has the same needs that you do? Can two species learn to speak each other’s languages to live in territorial harmony?


A common nightingale.
Photo by Frebeck at Wikimedia Commons.

A thrush nightingale.
Photo by Locaguapa at Wikimedia Commons.

Today at Accumulating Glitches, I tell the story of two species of nightingales and how they are learning to sing each other's songs to defend their territories! Check out the article here.

Caught in My Web: Memory Regeneration, Fish Sex, and the Physics of Swimming

For this edition of Caught in My Web, we explore the science of swimming and other underwater oddities.

1. If you are pondering great questions in life, such as "How is swimming different between a sperm and a sperm whale?", then you are in luck. The physics of how size influences the ability to swim is explained by Aatish Bhatia on TEDEd.

2. Neil Hammerschlag, a shark scientist and blogger for National Geographic, discusses the use of satellite tags for shark research.

3. Phys.org explains the science of side-to-side fish movement.

4. Robert Krulwich at NPR talks about headless planarians that regenerate their heads and their memories.

5. And the Beckman Institute tells you why Nemo would have become a girl if he had not found his dad:

Caught in My Web: Chimpanzee Memory, Beatbox-Dancing Cockroach Legs, Cute Animals Behaving Badly, Behavioral Catastrophe, and Scientifically Accurate Spider Man

This week in Caught in My Web, I share some quirky web pages that open our eyes to some aspects of animal behavior that we don't often think about:

1. Lee Rannals describes on redOrbit research that discovered that chimpanzees use long-term memory of how various trees produced fruit in previous years to forage today.

2. On TEDEd, Greg Gage hooks up a cockroach leg to a device that allows us to hear nerve impulses! And if that wasn’t cool enough, he then gets the cockroach leg to dance to a human beatbox. You have to see this.

3. Cute animals behaving badly. Need I say more?

4. Animals will sometimes continue their behaviors even when they end in catastrophe. George Dvorsky at IO9 describes 8 of the most deadly.

5. And if ADHD's Scientifically Accurate DuckTales was too much for you, DO NOT WATCH Scientifically Accurate Spider Man:

The Real Catfish of Lake Tanganyika

Photo of Manti Te'o by Shotgun Spratling
and Neon Tommy at Wikimedia

Poor Manti Te’o may just be the most gullible schlub on the planet. For those of you that haven’t heard the story, the Notre Dame linebacker and runner-up for the 2012 Heisman Trophy led his team to the BCS National Championship Game, despite (or perhaps inspired by) the tremendous personal losses he has suffered this season. Last September, Te’o learned first of the death of his grandmother, and then within hours learned of the death of his girlfriend, Lennay Kekua. But after months of grieving and playing his heart out, Te’o began to receive phone calls from his “dead” girlfriend, telling him she missed him. Totally freaky, right? Notre Dame hired investigators to look into the undead girlfriend and they discovered that not only is Kekua not dead, she was never alive. The girl never existed. And what of Te’o’s relationship with her? According to Te’o, he never actually met her in person: Their entire long-term relationship took place online and over the phone, so he never realized that her entire persona was a fraud. He was completely and totally catfished.

He was what?

The top definition of catfish at Urban Dictionary reads:

“A catfish is someone who pretends to be someone they're not using Facebook or other social media to create false identities, particularly to pursue deceptive online romances.

Did you hear how Dave got totally catfished last month?! The fox he thought he was talking to turned out to be a pervy guy from San Diego!”

The term apparently originates with the 2010 documentary, Catfish, about a young man who falls in love with a woman on Facebook… who turns out to be someone else. Ew. But why the term catfish? A story in the movie explains that when cod are shipped from North America to Asia, their inactivity can result in mushy meat. Fishermen discovered that putting catfish in the cod tanks will keep the cod active and preserve meat quality. Like catfish for cod, the guy philosophizes, people that have deceptive identities keep idle people active. (The producers of the documentary now produce an MTV series by the same name about this online phenomenon).

But it’s not like real catfish can imitate others… Or do they?

Three poisionous Lake
Tanganyikan catfish. Figure from
Jeremy's 2010 Evolution paper.

A 2010 paper by Jeremy Wright at the University of Michigan at Ann Arbor documents the first known case of mimicry in catfish. There are several types of mimicry in the animal world. In this case, Jeremy was investigating functional Müllerian mimicry, a phenomenon in which two or more poisonous species mimic each other's predator-deterring warning signals (as opposed to Batesian mimicry, where a non-poisonous animal looks like a poisonous one). It may seem excessive to have both poison and warning coloration, but poison only helps after you’ve been bit. If your predators are smart enough to learn from experience, you can benefit from having more poisonous buddies around that look just like you so that if a predator bites just one of you it will then learn to avoid all of you. Sometimes it pays to look just like everyone else.

But just because you look like everyone else doesn’t mean that it is because you’re imitating others. I mean, maybe that’s just the way you look. So how do you know if a bunch of animals that look like one another are using functional Müllerian mimicry?

Jeremy studied a number of similarly-colored, poisonous and closely-related catfish species in the African Great Lake, Lake Tanganyika. All of these Tanganyikan catfish species (from the Synodontis genus) have dark spots on a yellowish background and dark fins with white borders. Could this be because of functional Müllerian mimicry?

Jeremy put a bunch of largemouth bass each into their own tank. Largemouth bass are predators that use their vision to find and eat most any fish that will fit in their mouths. But these bass were from Michigan, so they’d never had any experience with a poisionous, spotted Synodontis catfish. A clear barrier divided each tank in half and the bass was placed on one side of the divider, and a bite-sized fish was put on the other. The bite-sized fish was either a spotted and poisonous Synodontis multipunctata catfish, a spotted and poisonous Synodontis petricola catfish, or a not-spotted and not-poisonous minnow. He then counted how many times the bass struck the plastic divider in 5 minutes as a measure of how much that bass wanted to eat the bite-sized fish. After the 5 minutes were up, Jeremy removed the divider and watched to see if the bass ate the bite-sized fish. For each bass, he did this every day for 5 days, giving each bass the same species of bite-sized fish every day, so it could learn from its past experiences.

A naïve largemouth bass excited to eat a bitesized, but poisonous Synodontis petricola catfish.

A naïve largemouth bass gets to try to eat a bitesized, but poisonous Synodontis petricola catfish… and it doesn’t go so well for him.

A no-longer naïve largemouth bass gives his best death stare to a bitesized, but poisonous Synodontis petricola catfish. Videos provided by Jeremy Wright.

On the first day with the bite-sized fish, all the bass struck at the divider equally regardless of whether it was a spotted poisonous catfish or a minnow. But after their first bite, the bass given spotted poisonous catfish quickly lost their interest in them even though the bass given minnows continued to vigorously strike at them every day. When Jeremy later gave them a different species of bite-sized fish, those previously given a spotted poisonous catfish avoided both species of spotted poisonous catfish, but readily ate the minnows. So the bass had learned. Spotted catfish: bad! Minnows: yum! And the spotted catfish look was transferable between the two species… the hallmark of functional Müllerian mimicry. Further analysis of the venom revealed that these catfish species were all equally poisonous: Painful, but not deadly.

Online catfish like Lennay Kekua are usually like these real-life spotted poisonous catfish: painful, but not (usually) deadly. And they typically have facebook pages and twitter accounts full of sexy photos and superficial chatter. If we’re smart, we can learn to avoid them. Do you know if all your “friends” on social media sites are who they say they are?

Want to know more? Check this out:

Wright, J. (2011). CONSERVATIVE COEVOLUTION OF MÜLLERIAN MIMICRY IN A GROUP OF RIFT LAKE CATFISH Evolution, 65 (2), 395-407 DOI: 10.1111/j.1558-5646.2010.01149.x