The Smell of Fear

A repost of an original article from October 24, 2012.

Several animals, many of them insects, crustaceans and fish, can smell when their fellow peers are scared. A kind of superpower for superwimps, this is an especially useful ability for prey species. An animal that can smell that its neighbor is scared is more likely to be able to avoid predators it hasn’t detected yet.

Who can smell when you're scared? Photo provided by Freedigitalphotos.net.

“What does fear smell like?” you ask. Pee, of course.

I mean, that has to be the answer, right? It only makes sense that the smell of someone who has had the piss scared out of them is, well… piss. But do animals use that as a cue that a predator may be lurking?

Canadian researchers Grant Brown, Christopher Jackson, Patrick Malka, Élisa Jaques, and Marc-Andre Couturier at Concordia University set out to test whether prey fish species use urea, a component of fish pee, as a warning signal.


A convict cichlid in wide-eyed
terror... Okay, fine. They're
always wide-eyed. Photo by
Dean Pemberton at Wikimedia.

First, the researchers tested the responses of convict cichlids and rainbow trout, two freshwater prey fish species, to water from tanks of fish that had been spooked by a fake predator model and to water from tanks of fish that were calm and relaxed. They found that when these fish were exposed to water from spooked fish, they behaved as if they were spooked too (they stopped feeding and moving). But when they were exposed to water from relaxed fish, they fed and moved around normally. Something in the water that the spooked fish were in was making the new fish act scared!

To find out if the fish may be responding to urea, they put one of three different concentrations of urea or just plain water into the tanks of cichlids and trout. The cichlids responded to all three doses of urea, but not the plain water, with a fear response (they stopped feeding and moving again). The trout acted fearfully when the two highest doses of urea, but not the lowest urea dose or plain water, were put in their tank. Urea seems to send a smelly signal to these prey fish to “Sit tight – Something scary this way comes”. And the more urea in the water, the scarier!

But wait a minute: Does this mean that every time a fish takes a wiz, all his buddies run and hide? That would be ridiculous. Not only do freshwater fish pee a LOT, many are also regularly releasing urea through their gills (I know, gross, right? But not nearly as gross as the fact that many cigarette companies add urea to cigarettes to add flavor).

The researchers figured that background levels of urea in the water are inevitable and should reduce fishes fear responses to urea. They put cichlids and trout in tanks with water that either had a low level of urea, a high level of urea, or no urea at all. Then they waited 30 minutes, which was enough time for the fish to calm down, move around and eat normally. Then they added an additional pulse of water, a medium dose of urea, or a high dose of urea. Generally, the more urea the fish were exposed to for the 30 minute period, the less responsive they were to the pulse of urea. Just like the scientists predicted.

A rainbow trout smells its surroundings.
Photo at Wikimedia taken by Ken Hammond at the USDA.

But we still don’t know exactly what this means. Maybe the initial dose of urea makes the fish hide at first, but later realize that there was no predator and decide to eat. Then the second pulse of urea may be seen by the fish as “crying wolf”. Alternatively, maybe the presence of urea already in the water masks the fishes’ ability to detect the second urea pulse. Or maybe both explanations are true.

Urea, which is only a small component of freshwater fish urine, is not the whole story. Urea and possibly stress hormones make up what scientists refer to as disturbance cues. Steroid hormones that are involved in stress and sexual behaviors play a role in sending smelly signals in a number of species, so it makes sense that stress hormones may be part of this fearful fish smell. But fish also rely on damage-released alarm cues and the odor of their predators to know that a predator may be near. Scientists are just starting to get a whiff of what makes up the smell of fear.

Want to know more? Check these out:

1. Brown, G.E., Jackson, C.D., Malka, P.H., Jacques, É., & Couturier, M-A. (2012). Disturbance cues in freshwater prey fishes: Does urea function as an ‘early warning cue’ in juvenile convict cichlids and rainbow trout? Current Zoology, 58 (2), 250-259

2. Chivers, D.P., Brown, G.E. & Ferrari, M.C.O. (2012). Evolution of fish alarm substances. In: Chemical Ecology in Aquatic Systems. C. Brömark and L.-A. Hansson (eds). pp 127-139. Oxford University Press, Oxford.

3. Brown, G.E., Ferrari, M.C.O. & Chivers, D.P. (2011). Learning about danger: chemical alarm cues and threat-sensitive assessment of predation risk by fishes. In: Fish Cognition and Behaviour, 2nd ed. C. Brown, K.N. Laland and J. Krause (eds). pp. 59-80, Blackwell, London.

The Smell of Fear

A reposting of an article from October 24, 2012.

Several animals, many of them insects, crustaceans and fish, can smell when their fellow peers are scared. A kind of superpower for superwimps, this is an especially useful ability for prey species. An animal that can smell that its neighbor is scared is more likely to be able to avoid predators it hasn’t detected yet.

Who can smell when you're scared? Photo provided by Freedigitalphotos.net.

“What does fear smell like?” you ask. Pee, of course.

I mean, that has to be the answer, right? It only makes sense that the smell of someone who has had the piss scared out of them is, well… piss. But do animals use that as a cue that a predator may be lurking?

Canadian researchers Grant Brown, Christopher Jackson, Patrick Malka, Élisa Jaques, and Marc-Andre Couturier at Concordia University set out to test whether prey fish species use urea, a component of fish pee, as a warning signal.



A convict cichlid in wide-eyed
terror... Okay, fine. They're
always wide-eyed. Photo by
Dean Pemberton at Wikimedia.

First, the researchers tested the responses of convict cichlids and rainbow trout, two freshwater prey fish species, to water from tanks of fish that had been spooked by a fake predator model and to water from tanks of fish that were calm and relaxed. They found that when these fish were exposed to water from spooked fish, they behaved as if they were spooked too (they stopped feeding and moving). But when they were exposed to water from relaxed fish, they fed and moved around normally. Something in the water that the spooked fish were in was making the new fish act scared!

To find out if the fish may be responding to urea, they put one of three different concentrations of urea or just plain water into the tanks of cichlids and trout. The cichlids responded to all three doses of urea, but not the plain water, with a fear response (they stopped feeding and moving again). The trout acted fearfully when the two highest doses of urea, but not the lowest urea dose or plain water, were put in their tank. Urea seems to send a smelly signal to these prey fish to “Sit tight – Something scary this way comes”. And the more urea in the water, the scarier!

But wait a minute: Does this mean that every time a fish takes a wiz, all his buddies run and hide? That would be ridiculous. Not only do freshwater fish pee a LOT, many are also regularly releasing urea through their gills (I know, gross, right? But not nearly as gross as the fact that many cigarette companies add urea to cigarettes to add flavor).

The researchers figured that background levels of urea in the water are inevitable and should reduce fishes fear responses to urea. They put cichlids and trout in tanks with water that either had a low level of urea, a high level of urea, or no urea at all. Then they waited 30 minutes, which was enough time for the fish to calm down, move around and eat normally. Then they added an additional pulse of water, a medium dose of urea, or a high dose of urea. Generally, the more urea the fish were exposed to for the 30 minute period, the less responsive they were to the pulse of urea. Just like the scientists predicted.

A rainbow trout smells its surroundings.
Photo at Wikimedia taken by Ken Hammond at the USDA.

But we still don’t know exactly what this means. Maybe the initial dose of urea makes the fish hide at first, but later realize that there was no predator and decide to eat. Then the second pulse of urea may be seen by the fish as “crying wolf”. Alternatively, maybe the presence of urea already in the water masks the fishes’ ability to detect the second urea pulse. Or maybe both explanations are true.

Urea, which is only a small component of freshwater fish urine, is not the whole story. Urea and possibly stress hormones make up what scientists refer to as disturbance cues. Steroid hormones that are involved in stress and sexual behaviors play a role in sending smelly signals in a number of species, so it makes sense that stress hormones may be part of this fearful fish smell. But fish also rely on damage-released alarm cues and the odor of their predators to know that a predator may be near. Scientists are just starting to get a whiff of what makes up the smell of fear.

Want to know more? Check these out:

1. Brown, G.E., Jackson, C.D., Malka, P.H., Jacques, É., & Couturier, M-A. (2012). Disturbance cues in freshwater prey fishes: Does urea function as an ‘early warning cue’ in juvenile convict cichlids and rainbow trout? Current Zoology, 58 (2), 250-259

2. Chivers, D.P., Brown, G.E. & Ferrari, M.C.O. (2012). Evolution of fish alarm substances. In: Chemical Ecology in Aquatic Systems. C. Brömark and L.-A. Hansson (eds). pp 127-139. Oxford University Press, Oxford.

3. Brown, G.E., Ferrari, M.C.O. & Chivers, D.P. (2011). Learning about danger: chemical alarm cues and threat-sensitive assessment of predation risk by fishes. In: Fish Cognition and Behaviour, 2nd ed. C. Brown, K.N. Laland and J. Krause (eds). pp. 59-80, Blackwell, London. 3.

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

Fatal Attraction: Praying Mantises (A Guest Post)

By Britta Bibbo

We all know the character: an incredibly beautiful woman that seduces the rough-and-tumble action hero, only for him to later find himself chained up over a lava pit with sharks in it! …Or something like that. A “femme fatal” is the idea of a beautiful woman who leads men to their demise. None are more perfect for this role than the female praying mantis. Praying mantis females practice the art of deception through sexual cannibalism. It’s exactly how it sounds: the male is attracted to the female and tries to make some babies, but instead ends up being devoured. Sexual cannibalism hardly seems like a good strategy for keeping the mantis population up, but some argue it’s merely females taking advantage of every scrap of food they can find… even if it’s a loving male.

False garden mantis (Pseudomantis albofimbriata). Image by Donald Hobern from Wikimedia Commons.

When male mantises encounter a female in the wild they only have one thing on the brain, while a female may be more interested in self-preservation. If she hasn’t encountered food for a few days she will be VERY hungry and not all that interested in mating; in many species of mantises it is known that female mantises will eat males, even while having sex! So how do female mantises attract males?

For most insects, females are able to attract males with pheromones, chemicals released from an individual that affect other individuals of the same species. For instance, females can emit pheromones that will be telling of their age, reproductive status, and body condition. Males are able to detect pheromones from great distances and these pheromones play a role in allowing a male to determine how attractive a female could be. Before any sexy time can begin, females have to show that they are open to male advances. Showing a male you’ve never met before that you’re interested can be a difficult task- so females typically emit pheromones that are known as honest signals. These signals accurately convey female interest in mating, as well as her reproductive status, age, and body condition. Because the majority of females are being honest, males don’t have to think twice about their mate’s intentions. This is where female deception comes into play. If a female takes advantage of the lack of male wariness, she could end up with an easy meal. This deception by the females is what scientists know as the Femme Fatale hypothesis. This hypothesis explains that female mantises are naturally selected to deceive male mantises, and exploit them as food. This idea hasn’t had much backing evidence until Dr. Kate Barry of Macquarie University in Sydney, Australia sought to test this hypothesis with the false garden mantis (Pseudomantis albofimbriata).

After considering the test subjects and how the mantises communicate, Kate expected one of three possible outcomes:

1. There will be no pattern between female hunger and male attraction (if female false garden mantises are not femme fatales and false garden mantis pheromones do not communicate feeding-related information).

2. The well-fed females will attract the most males, while hungry females will attract the fewest males (if female false garden mantises are not femme fatales and females are always honest about their quality and willingness to mate).

3. The hungriest females will attract the most males, while well-fed females will still attract some males (if female false garden mantises are femme fatales and females are dishonest about their quality and willingness to mate when they are hungry).

To test her expectations, Kate gathered juvenile mantises that were close to their adult forms to have many male and female mantises that have no previous mating experience. Once the mantises were adults, females were given different feeding regimens to have a range of hunger. Categories included Good (well-fed), Medium (slightly less fed), Poor (hungry), and Very Poor (very, very hungry). Adult mantises were housed in a circular cage that separated each female individually around the edge, while the males were kept in the center.

Diagram of cage experiment was conducted in. Image by Britta Bibbo.

To allow the males to smell the female pheromones, researchers separated males by special walls that the males could not see through, but could still detect the pheromones given off by a female. The number of males on a female’s side of the cage was used to measure how attractive her pheromones were to the males.

The results of this study concluded that pheromones produced by the females that were very hungry were the most attractive to males. Through deception, the hungriest females are seen as sexier than well-fed, healthy females that are willing to mate! This result is surprising; normally females that are well-fed are seen as “sexier” because they have more nutrients available to them, making them more fertile. Hungry females have fewer nutrients available to them, making them less fertile, and therefore not as “sexy”. These hungry female mantises are advertising themselves as well-fed, fertile, and ready to rock when really, they’re not. Simply put, these results show that males are being catfished, and then consumed. Whether hungry females are actively trying to deceive males or if it’s just coincidental still needs to be looked into, but for now, be thankful for a partner who will see you as more than just a piece of meat!

Literature Cited:

Barry, K. (2014). Sexual deception in a cannibalistic mating system? Testing the Femme Fatale hypothesis Proceedings of the Royal Society B: Biological Sciences, 282 (1800), 20141428-20141428 DOI: 10.1098/rspb.2014.1428

How Fungus Makes Ant Zombies

"Ants biting the underside of leaves as a result of infection
by O. unilateralis. The top panel shows the whole leaf with
the dense surrounding vegetation in the background and the
lower panel shows a close up view of dead ant attached to
a leaf vein. The stroma of the fungus emerges from the back
of the ant's head and the perithecia, from which spores are
produced, grows from one side of this stroma, hence the
species epithet. The photograph has been rotated
to aid visualization." Image and caption by David P. Hughes
and Maj-Britt Pontoppidan at Wikimedia Commons.

The parasitic fungus, Ophiocordyceps unilateralis sensu latu (O. unilateralis, for short), infects the brains of Carpenter ants, turning them into zombies that live and die for the sole purpose of helping the fungus thrive and reproduce. Under the influence of the fungus, zombie Carpenter ants leave their nests at an odd yet specific time, move randomly and convulsively, and climb up the north side of a plant to almost exactly 25 cm, where they bite the leaf vein. Once they bite the leaf, the muscles of their mandibles (mouth parts) deteriorate, causing lockjaw and fixing the ant victim in place while its legs kick and twitch. After a few hours, the movement stops as the fungus kills the ant, continues to grow throughout the victim's head, and then sprouts out of the back of the head. The fungus anchors itself to the plant and releases antimicrobial chemicals to protect itself and grows fruiting bodies from the ant's head to release its spores, spawning the next generation of fungus. O. unilateralis has been known to infect and wipe out entire Carpenter ant colonies, leaving dense aerial graveyards of ant carcasses in its wake.

Today at Accumulating Glitches, I talk about new research that has used genetic techniques to determine how this parasitic fungus takes over the minds of its ant victims. Check it out here.

And to learn more, check this out:

de Bekker, C., Ohm, R.A., Loreto, R.G., Sebastian, A., Albert, I., Merrow, M., Brachmann, A. and Hughes, D.P. Gene expression during zombie ant biting behavior reflects the complexity underlying fungal parasitic behavioral manipulation, BMC Genomics, 16:620, 1-23 (2015). DOI 10.1186/s12864-015-1812-x.

Cooperating for Selfish Reasons

An Ethiopian Wolf photographed by Gert Vankrunkelsven.
Image available at Wikimedia.

If you were a young adult Ethiopian wolf, you would have a choice to make: Should you be a member of a monogamous breeding pair or a helper to an already established breeding pair (who are probably your parents)? The choice seems obvious, right? I mean, who wants to be a helper? Why should you forgo all the glory and status of being part of the breeding pair to be a babysitter?

Today I am revisiting my thoughts on the motivations to cooperate from an article I wrote in the early days of The Scorpion and the Frog. You can read the article in it's entirety here.

Animal Biology in Science Fiction: The Color of Distance

Ani and two of her community’s elders are foraging when they stumble upon two seemingly lifeless aliens. They are able to restore one of the aliens to health and what follows is a thought-provoking story of first contact between alien worlds. This is Amy Thompson’s The Color of Distance, a science fiction novel written from perspectives that alternate between Juna (the human “alien” scientist stranded on a foreign planet) and Ani (the Tendu female that found her).

The Color of Distance is a rare science fiction story in that the science focuses on possibilities of ecology and physiology. The Tendu are a sentient species with many physical attributes similar to our own amphibians. They have a deep understanding of the ecology of their planet and they take responsibility for the sustainability of their ecosystems. We learn about their planet’s species and ecological relationships through the eyes and thoughts of Juna, a human scientist that was stranded on a mission to explore the planet. The parallels between the species and ecologies on this fictional planet and Earth are too similar for my critical science brain to believe, but they serve well to foster in us more of an appreciation for the wondrous complexities of our own planet.

The Tendu role as caretakers of their planet’s species is supported by their remarkable physiological abilities. The Tendu have fleshy spurs on their wrists, called allu, that they use to communicate and learn about the animals around them. By sinking their spurs into another animal, the Tendu can learn about that animal’s health, diet, emotional state, reproductive state, and many other attributes. Furthermore, through their allu they can manipulate other animals’ health, monitoring them, healing them, even physically altering them! This is a fun idea, but could this even be remotely possible?

In fact, many species on our own planet already have similar abilities! Many animals produce pheromones, chemical compounds that, when detected by another animal, communicate that animal’s health, diet, emotional state, reproductive state, and many other attributes. Many species (including many mammals and insects) use airborne pheromones, but fish and other aquatic animals can perceive chemicals in the water the same way. It is not much more of a conceptual leap to imagine an animal that can inject a spur into another animal’s body to “taste” chemicals that relate to that animal’s health and emotional state. If that spur were also able to release chemicals and compounds, then this could be a means to influence the receiving animal’s health and emotional state as well.

Thompson’s novel also takes us through the emotional journey of a woman trying to make a life for herself in a new land surrounded by people and customs she doesn’t understand. Her writing regularly left me lost in memories of my days in Peace Corps and will likely resonate with anyone who has spent a significant amount of time living abroad.

If you are looking to curl up with a blanket and a good book, this is a good one! It will get you thinking about physiology, ecology, culture and politics in a whole new way.

Have you read The Color of Distance? Can you recommend another science fiction book that focuses on physiology or behavior? If so, please comment below!

For more animal physiology and behavior in science fiction, go here.

We Are Each A Community



Lactobacillus (the purple rod-shaped things)
is a common bacterial species in reproductive
tracts. Image by Janice Carr from the
CDC at Wikimedia Commons.

In our world of antibacterial soaps, we have learned that bacteria are evil, dirty, sickness-causing agents to be eliminated at all costs. Although some bacteria can cause sickness, bacteria in general are actually a critical component of animal bodies. A human body has ten times as many bacterial cells as human cells and a hundred times as many bacterial genes as human genes, and this pattern is likely true for most animals. We animals have bacterial communities living on our skin, fur, feathers, scales and exoskeletons. We have bacteria in our guts, respiratory systems and reproductive tracts. And bacteria live in glands that are specialized for grooming or scent communication. These bacteria play critical roles not just in how our bodies work, but also in how we behave.

This week at Accumulating Glitches I talk about how all animals (including ourselves) include a community of microbes, such as bacteria. Even more amazing is that many of these bacteria are critical for our health and behavior. Check it out here.

And to learn more, check this out:

Archie, E.A., & Theis, K.R. (2011). Animal behaviour meets microbial ecology Animal Behaviour, 82, 425-436 DOI: 10.1016/j.anbehav.2011.05.029

Caught in My Web: What Your Dog Really Thinks About You, Understanding Gestures, Camera Traps and Pruney Fingers

Image by Luc Viatour at Wikimedia Commons.

This week in Caught in My Web, I share what I found when pondering interactions between humans and animals, what we have learned from camera traps, and what our pruney fingers in the bath may have to teach us about our animal nature.

1. Greg Berns, a psychiatry professor at Emory University, set out to use an fMRI scanner to learn more about what dogs think about their humans. Read his story here at Psychology Today. And check out this video describing The Dog Project:

2. Although dogs may be “man’s best friend”, they have failed numerous tests in understanding our gestures, such as pointing, without training. Even chimpanzees require training before understanding the meaning of human pointing. But elephants are now the first non-human species that seems to innately understand human pointing, naturally investigating objects pointed to (comparable to a 1-year-old human). Jack Flanagan discusses this research at NewScientist.

3. At The Thoughtful Animal, Jason Goldman discusses camera traps (weather-resistant cameras that use motion detection sensors to photograph wildlife) and how they are used in animal research. He also reveals the secret ingredient to luring jaguars to the cameras at You’ll Never Guess How Biologists Lure Jaguars To Camera Traps.

4. While we’re talking about camera traps, Siberian tiger researchers set up camera traps in southeastern Russia. One of their cameras took a series of 3 amazing pictures of a golden eagle attacking a sika deer. Check out the pictures at National Geographic.

5. Ever wonder why your fingers get pruney in the bath? Maybe it is a primate adaptation! Mark Changizi explains why at TEDEd:

What Comes First: The Signal or the Response?

Jewel wasps show us how new communication systems may have come to be.
Photo by M.E. Clark at Wikimedia Commons.

Finding and attracting a mate is tricky business for most species. It can be quite helpful then to have a species-specific signal that is sent and received by members of your own species, but not perceived as well by predators. Chemical signals (those we perceive through smell and taste) are among the most diverse and specific signals produced in the animal kingdom, so they make good candidates for these species-specific mating signals. Sex pheromones are chemical compounds released by an animal that attract animals of the same species but opposite sex. They are often so specific that other species can’t smell them at all, which makes them useful as a secret communication line for just that species. But this specificity raises an intriguing question: What develops first: the ability to make the pheromone or the ability to perceive it?

This week I tell the story of how jewel wasps shed light on this chicken-or-the-egg problem at Accumulating Glitches. Check it out here.

And to learn more, check these out:

1. Lassance, J., & Löfstedt, C. (2013). Chemical communication: A jewel sheds light on signal evolution Current Biology, 29 (3) DOI: 10.1016/j.cub.2013.03.055

2. Niehuis, O., Buellesbach, J., Gibson, J.D., Pothmann, D., Hanner, C., Mutti, N.S., Judson, A.K., Gadau, J., Ruther, J., & Schmitt, T. (2013). Behavioural and genetic analyses of Nasonia shed light on the evolution of sex pheromones Nature, 494, 345-348 DOI: 10.1038/nature11838

The Craptastic Conversations of the Black Rhinoceros

What are you saying with your smells? Image by freedigitalphotos.net.

Animals communicate in all kinds of ways: with vocalizations, body language, vibrations, and even odors. In fact, compared to most species, we are pathetic in our abilities to communicate with body odor. With just a whiff of eau de crotch, many animals can decipher that individual’s species, sex, age, health status, reproductive status, emotional state, and dietary history. Some species can go so far as to make out that individual’s exact identity (*Sniff Sniff* Oh! Hi Mike!).

There are a lot of advantages to using odors to communicate. For one thing, messages sent by smell are more likely to be honest than messages sent by other means. (You might be able to do a pretty good Shakira impersonation, but you can’t hide the fact that you had a tuna sandwich for lunch and haven’t brushed your teeth since). Another advantage is that unlike other signal types, an odor signal can be left behind, kind of like those sticky-notes you leave on your food in the fridge.

How do scientists know which species use odors to communicate and what information these signals contain? This investigatory process involves a lot of reasoning.

A solitary black rhino. Photo by John and Karen Hollingsworth
at the US Fish and Wildlife Service.

Wayne Linklater, Katha Mayer and Ron Swaisgood, an international team of researchers associated with Victoria University of Wellington in New Zealand, Nelson Mandela Metropolitan University in South Africa, University of Potsdam in Germany, and the San Diego Zoo Institute for Conservation Research in California, set out to test whether black rhinoceros use odor to communicate. Although rhinos lack the specialized scent glands that many smell-communicating species have, there are many reasons to suggest that they are a likely species to communicate this way.

A photo of field assistant Brayden
Crocker with rhino dung scrape mark.
Photo by Wayne Linklater.

Black rhinos are solitary. Females often have overlapping ranges, but males’ territories only overlap at their boundaries. This means that they would rarely encounter one another and would benefit from a means to leave “sticky-notes” behind to indicate where their territories are. Furthermore, despite their poor eyesight, male black rhinos have a poop-ritual in which they scrape at the ground and spread their dung. Although female rhinos don’t spread their poo, they do spray their pee when they are ready to mate.

Between 2004 and 2006, the Ezemvelo KwaZulu-Natal Wildlife Veterinary and Game-Capture Team captured a number of black rhinoceros from the Ezemvelo KwaZulu-Natal Wildlife Reserves in South Africa in order to relocate them to other reserves for conservation purposes. At this time, Wayne, Katha, and Ron collected dung from rhinos with known sexes and ages. They stored the dung in labeled plastic bags and froze them to preserve the odor freshness for a series of experiments to explore the extent of the black rhinos’ abilities to communicate with their bodily waste.

In one experiment, the researchers asked whether black rhinos could differentiate between the dung of males and females and between the dung of adults and immature subadults. They presented rhinos with the dung of young males, young females, adult males and adult females, and then measured how many times they sniffed each and how long they spent sniffing. The rhinos spent more time sniffing male dung than female dung. This means that rhino poop likely communicates the sex of the pooper. Rhinos also responded differently to adult and subadult poop, suggesting that they can tell whether the pooper is an adult or not.

In order to test whether rhinos may be able to tell the individual identity of the pooper, they did a habituation-dishabituation test. Habituation is when an animal gets used to something that happens repeatedly and stops responding to it. For example, the first time you heard Gangnam Style, you probably stopped what you were doing and maybe even learned the dance. But now it has been so ridiculously over-played that when you hear it, you just ignore it. Dishabituation happens when an animal is exposed to something slightly different and has a heightened response again. Kind of like the excitement over Psy’s new song, Gentleman, even though it sucks.

A photo of rhino performing flehmen, a behavior that helps
waft odors for better odor detection. Photo by Wayne Linklater.

Wayne, Katha, and Ron exposed rhinos to the same individual’s dung three times to see if their interest in it waned. With each presentation, the rhinos spent a little less time sniffing it. When the researchers put poop from a different rhino (that was the same sex and age as the first pooper) in front of them, their interest returned. This suggests that rhinos can tell the individual identity of the pooper from his/her poop.

But can rhinos use their poop like “sticky-notes”? The researchers aged dung for 1, 4, 16 and 32 days and put them in front of rhinos to smell. Their response was the same, no matter how old the dung was. This indicates that rhinos can spread their poop to leave an “I was here” message for at least a month.

As fun as it may be to spend years studying rhinoceros poop, there are some important uses for research like this. Black rhinos are critically endangered, largely due to hunting, poaching and habitat loss. In fact, Mozambique's Limpopo National Park declared the last of their rhino population killed as recently as last month. Conservation efforts such as captive breeding programs and reintroductions have helped in several areas, but have not been enough to sustain the populations. Conservationists could apply this knowledge of how rhinoceros use dung odors to communicate to these breeding and reintroduction efforts in order to make them considerably more successful.


Want to know more? Check this out:

Linklater, W., Mayer, K., & Swaisgood, R. (2013). Chemical signals of age, sex and identity in black rhinoceros Animal Behaviour, 85 (3), 671-677 DOI: 10.1016/j.anbehav.2012.12.034

Political Animals

Now that we are finally on the other side of one of the longest, most expensive political campaign seasons of United States history, we find ourselves with a new mixed-bag of leaders. Our nation’s decision-makers include career politicians and new freshman politicians; they include lawyers, military members, doctors, businessmen, farmers, ministers, educators, scientists, pilots, and entertainers; they include Protestants, Catholics, Jews, Quakers, Mormons, Buddhists and Muslims; they include white Americans, African Americans, Asian Americans, and Hispanic and Latino Americans; they include men and women; they include straight and gay people; and oh yeah, they include Republicans and Democrats. With so many differences that generate so many viewpoints, how will they ever find common ground to make the kind of decisions that will move our nation in a positive direction?

Hey, Look guys! We make a peace sign! Image from Wikimedia.

Research into group decision-making in social animals has shown that ants, fish, birds, and bees have all discovered strategies to make intelligent group decisions. If they can do it, we can do it, right? What can we learn from these critters about harnessing the knowledge in all of us to move our whole group in the best possible direction? We will explore these insights in this post, which is a mash-up of two previous posts. To see the originals, check out Can a Horde of Idiots Be a Genius? and Why This Horde of Idiots Is No Genius.

Jean-Louis Deneubourg, a professor at the Free University of Brussels, and his colleagues tested the abilities of Argentine ants (a common dark-brown ant species) to collectively solve foraging problems. In one of these studies, the ants were provided with a bridge that connected the nest to a food source. This bridge split and fused in two places (like eyeglass frames), but at each split one branch was shorter than the other, resulting in a single shortest-path and multiple longer paths. After a few minutes, explorers crossed the bridge (by a meandering path) and discovered the food. This recruited foragers, each of which chose randomly between the short and the long branch at each split. Then suddenly, the foragers all started to prefer the shortest route. How did they do that?

This figure from the Goss et al 1989 paper in Naturwissemschaften shows (a) the design of a single module, (b) ants scattered on the bridge after 4 minutes (I promise they’re there), and (c) ants mostly on the shortest path after 8 minutes

You can think of it this way: a single individual often tries to make decisions based on the uncertain information available to it. But if you have a group of individuals, they will likely each have information that differs somewhat from the information of others in the group. If they each make a decision based on their own information alone, they will likely result in a number of poor decisions and a few good ones. But if they can each base their decisions on the accumulation of all of the information of the group, they stand a much better chance of making a good decision. The more information accumulated, the more likely they are to make the best possible decision.

In the case of the Argentine ant, the accumulated information takes the form of pheromone trails. Argentine ants lay pheromone trails both when leaving the nest and when returning to the nest. Ants that are lucky enough to take a shorter foraging route return to the nest sooner, increasing the pheromone concentration of the route each way. In this way, shorter routes develop more concentrated pheromone trails faster, which attract more ants, which further increase pheromone concentration of the shortest routes. In this way, an ant colony can make an intelligent decision (take the shortest foraging route) without any individual doing anything more intelligent than following a simple rule (follow the strongest pheromone signal).

Home is where the heart is. Photo of a bee swarm by Tom Seeley

Honeybee colonies also solve complicated tasks with the use of communication. Tom Seeley at Cornell University and his colleagues have investigated the honeybee group decision-making process of finding a new home. When a colony outgrows their hive, hundreds of scouts will go in search of a suitable new home, preferably one that is high off the ground with a south-facing entrance and room to grow. During this time, the house-hunters will coalesce on a nearby branch while they search out and decide among new home options. This process can take anywhere from hours to days during which the colony is vulnerable and exposed. But they can’t be too hasty: choosing a new home that is too small or too exposed could be equally deadly. Although each swarm has a queen, she plays no role in making this life-or-death decision. Rather, this decision is made by a consensus among 300-500 scout bees that results after an intense “dance-debate”.

If a scout finds a good candidate home, she returns to the colony and performs a waggle dance, a dance in which her body position and movements encode the directions to her site and her dancing vigor relates to how awesome she thinks the site is. Some scouts that see her dance may be persuaded to follow her directions and check out the site for themselves, and if impressed, may return to the hive and perform waggle dances too. Or they may follow another scout’s directions to a different site or even strike out on their own. Over time, scouts that are less enthusiastic about their discovered site stop dancing, in part discouraged by dancers for other sites that bump heads with them and beep at them in disagreement. Eventually, the majority of the dancing scouts are all dancing the same vigorous dance. But interestingly, few scouts ever visit more than one site. Better sites simply receive more vigorous “dance-votes” and then attract more scouts to do the same. Like ants in search of a foraging path, the intensity of the collective signal drives the group towards the best decision. Once a quorum is reached, the honeybees leave their branch as a single united swarm and move into their new home, which is almost always the best site. 

Each dot represents where on the body this dancer was head-bumped by a
dancer for a competing site. Each time she's bumped, she's a little less enthusiastic
about her own dance. Figure from Seeley, et al. 2012 paper in Science.

But groups can develop better solutions than individuals even without communication. Gaia Dell’Ariccia at the University of Zurich in Switzerland and her colleagues explored homing pigeon navigation by placing GPS trackers on the backs of pigeons and releasing them from a familiar location either alone or in a group of six. Because they were all trained to fly home from this site, they all found their way home regardless of whether they were alone or in a group. But as a flock, the pigeons left sooner, rested less, flew faster, and took a more direct route than did the same birds when making the trip alone. By averaging the directional tendencies of everyone in the group, they were able to mutually correct the errors of each individual and follow the straightest path.

What can we learn from these examples? Like individual congressmen and senators, in each of these examples each individual has limited and uncertain information, but each individual has information that may be slightly different than their neighbors’. This diversity can be our congress’ greatest asset, if they use it in the same way so many animals naturally do. Tom Seeley summarized these approaches based on his insights from years of watching honeybees:

Tom Seeley’s Five Habits of Highly Effective Hives

1. “Group members share a goal”.
This is easy for honeybees, but not as much for us. All of the honeybees in a swarm share the same goal: Find the best possible home as quickly as possible. People are not always similar in our goals, needs and wants and one person’s goals are sometimes in direct conflict with another person’s goals. The trick here is finding common ground.

2. “Group members search broadly to find possible solutions to the problem”.
Seek out information from as many sources as you can. Be creative. Use your personal experience. And if the group is diverse, there will be a broader range of personal experience to harness. Diversity increases the ability of a group to make the best decisions.

3. “Group members contribute their information freely and honestly”.
This requires a welcoming and supportive environment that withholds judgment of the individuals for the ideas expressed. You don’t have to agree with an idea to respect and listen to the person expressing it.

4. “Group members evaluate the options independently and they vote independently”.
Just as scout bees don’t dance for a site they have not visited and assessed themselves, we should not advocate possible solutions or candidates that we have not ourselves looked into and thought critically about. A group can only be smarter than the individuals in it if the individuals think for themselves.

5. “Group members aggregate their votes fairly”.
Everyone gets a vote and each one counts equally. ‘Nuff said.

We can learn a lot from these honeybees. Even when the stakes are high, we can make good decisions for our group if we are open, honest, inclusive, fair and think independently.

Want to know more? Check these out:

1. Couzin, I. (2009). Collective cognition in animal groups Trends in Cognitive Sciences, 13 (1), 36-43 DOI: 10.1016/j.tics.2008.10.002

2. List, C., Elsholtz, C., & Seeley, T. (2009). Independence and interdependence in collective decision making: an agent-based model of nest-site choice by honeybee swarms Philosophical Transactions of the Royal Society B: Biological Sciences, 364 (1518), 755-762 DOI: 10.1098/rstb.2008.0277

3. Seeley, T., Visscher, P., Schlegel, T., Hogan, P., Franks, N., & Marshall, J. (2011). Stop Signals Provide Cross Inhibition in Collective Decision-Making by Honeybee Swarms Science, 335 (6064), 108-111 DOI: 10.1126/science.1210361

4. Dell'Ariccia, G., Dell'Omo, G., Wolfer, D., & Lipp, H. (2008). Flock flying improves pigeons' homing: GPS track analysis of individual flyers versus small groups Animal Behaviour, 76 (4), 1165-1172 DOI: 10.1016/j.anbehav.2008.05.022

5. Honeybee Democracy by Thomas Seeley

6. The Smart Swarm by Peter Miller

7. The Wisdom of Crowds by James Surowiecki

The Smell of Fear

Several animals, many of them insects, crustaceans and fish, can smell when their fellow peers are scared. A kind of superpower for superwimps, this is an especially useful ability for prey species. An animal that can smell that its neighbor is scared is more likely to be able to avoid predators it hasn’t detected yet.

Who can smell when you're scared? Photo provided by Freedigitalphotos.net.

“What does fear smell like?” you ask. Pee, of course.

I mean, that has to be the answer, right? It only makes sense that the smell of someone who has had the piss scared out of them is, well… piss. But do animals use that as a cue that a predator may be lurking?

Canadian researchers Grant Brown, Christopher Jackson, Patrick Malka, Élisa Jaques, and Marc-Andre Couturier at Concordia University set out to test whether prey fish species use urea, a component of fish pee, as a warning signal.


A convict cichlid in wide-eyed
terror... Okay, fine. They're
always wide-eyed. Photo by
Dean Pemberton at Wikimedia.

First, the researchers tested the responses of convict cichlids and rainbow trout, two freshwater prey fish species, to water from tanks of fish that had been spooked by a fake predator model and to water from tanks of fish that were calm and relaxed. They found that when these fish were exposed to water from spooked fish, they behaved as if they were spooked too (they stopped feeding and moving). But when they were exposed to water from relaxed fish, they fed and moved around normally. Something in the water that the spooked fish were in was making the new fish act scared!

To find out if the fish may be responding to urea, they put one of three different concentrations of urea or just plain water into the tanks of cichlids and trout. The cichlids responded to all three doses of urea, but not the plain water, with a fear response (they stopped feeding and moving again). The trout acted fearfully when the two highest doses of urea, but not the lowest urea dose or plain water, were put in their tank. Urea seems to send a smelly signal to these prey fish to “Sit tight – Something scary this way comes”. And the more urea in the water, the scarier!

But wait a minute: Does this mean that every time a fish takes a wiz, all his buddies run and hide? That would be ridiculous. Not only do freshwater fish pee a LOT, many are also regularly releasing urea through their gills (I know, gross, right? But not nearly as gross as the fact that many cigarette companies add urea to cigarettes to add flavor).

The researchers figured that background levels of urea in the water are inevitable and should reduce fishes fear responses to urea. They put cichlids and trout in tanks with water that either had a low level of urea, a high level of urea, or no urea at all. Then they waited 30 minutes, which was enough time for the fish to calm down, move around and eat normally. Then they added an additional pulse of water, a medium dose of urea, or a high dose of urea. Generally, the more urea the fish were exposed to for the 30 minute period, the less responsive they were to the pulse of urea. Just like the scientists predicted.

A rainbow trout smells its surroundings.
Photo at Wikimedia taken by Ken Hammond at the USDA.

But we still don’t know exactly what this means. Maybe the initial dose of urea makes the fish hide at first, but later realize that there was no predator and decide to eat. Then the second pulse of urea may be seen by the fish as “crying wolf”. Alternatively, maybe the presence of urea already in the water masks the fishes’ ability to detect the second urea pulse. Or maybe both explanations are true.

Urea, which is only a small component of freshwater fish urine, is not the whole story. Urea and possibly stress hormones make up what scientists refer to as disturbance cues. Steroid hormones that are involved in stress and sexual behaviors play a role in sending smelly signals in a number of species, so it makes sense that stress hormones may be part of this fearful fish smell. But fish also rely on damage-released alarm cues and the odor of their predators to know that a predator may be near. Scientists are just starting to get a whiff of what makes up the smell of fear.

Want to know more? Check these out:

1. Brown, G.E., Jackson, C.D., Malka, P.H., Jacques, É., & Couturier, M-A. (2012). Disturbance cues in freshwater prey fishes: Does urea function as an ‘early warning cue’ in juvenile convict cichlids and rainbow trout? Current Zoology, 58 (2), 250-259

2. Chivers, D.P., Brown, G.E. & Ferrari, M.C.O. (2012). Evolution of fish alarm substances. In: Chemical Ecology in Aquatic Systems. C. Brömark and L.-A. Hansson (eds). pp 127-139. Oxford University Press, Oxford.

3. Brown, G.E., Ferrari, M.C.O. & Chivers, D.P. (2011). Learning about danger: chemical alarm cues and threat-sensitive assessment of predation risk by fishes. In: Fish Cognition and Behaviour, 2nd ed. C. Brown, K.N. Laland and J. Krause (eds). pp. 59-80, Blackwell, London. 3.