Monday, October 20, 2014

Caught in My Web: Creepy Animals, Animal Disguises, Pet-Love After Death, and Ebola

For this Halloween edition of Caught in My Web, we check out what the web has to say about creepy animal stories.


1. The CDC addresses questions about whether pets can get ebola

2. Julie Hecht, the author of Dog Spies at Scientific American blogs explores the love between dogs and their owners from beyond the grave

3. BuzzFeed presents 8 surprisingly creepy animals.



4. Dr. Doolittle at ScienceBlogs talks about the eyeless Mexican cavefish

5. Sara Mynott at Saltwater Science, a blog at Nature’s Scitable blog network, explains flounder disguises (they’re not just for Halloween)

Monday, October 13, 2014

Is That Lizard Possessed!? (A Guest Post)

By Tawny Liebe

Image from Chuck Heston on Flickr.
A creature straight from the depths of hell… or at least as close as you can get on this planet. The Texas horned lizard or “horny toad” is found in the deserts of the southwest United States and has an unusual adaptation to deter predation exclusively from a few species of canines. When threatened by coyotes, foxes, and dogs, the horned lizard squirts blood from its eyes to hit targets up to three feet away! A total of six species of horned lizard have been proven to respond this way to canine attack, while none have responded this way to other predators, such as the grasshopper mouse or the roadrunner. So what is the deal? How do they do this and how does it work as predator defense?

Veins have one-way valves
to prevent backflow.
Drawing by Tawny Liebe.

Before we get to that, there are a few things you need to know. First of all, the circulatory system includes a network of arteries and veins. Arteries carry blood full of oxygen to body tissues while veins carry blood that lacks oxygen from the rest of the body back to the heart. This means that for the blood, in someone’s foot for instance, to get all the way back to the heart through the veins, the blood must work against gravity. When you (or this lizard or many other species) move, blood is propelled from one chamber in the vein to the next until it reaches the heart. The blood is prevented from flowing back into the previous chamber by one-way valves, causing the blood to pool.

In order to squirt blood from their eyes, horned lizards manipulate the network of veins in their head so that they build up pressure, like a volcano getting ready to blow. By constricting a pair of throat muscles unique to reptiles, they effectively close their jugular veins and increase the blood pressure in their head. This is thought to be enhanced by another pair of muscles between the jugular veins and the eyes that help increase the blood pressure in the head even further, causing the blood to move into the sinuses of the eyes. The pressure continues to build until the blood breaks through the wall of the eye socket into the eyelids where it is forced into the tear duct and erupts like a Mentos in a Coke bottle all over whatever is chomping at the poor little lizard.

As if these lizards couldn’t get any more amazing, recent studies have shown that it is actually a compound in their blood that canines don’t like. Scientists have also found that this chemical is in their circulating blood, not just the blood that is squirted from their eye, rejecting an earlier hypothesis that the chemical is picked up in the tear duct. To top off all of this awesomeness, the chemical may be acquired through its main food source- harvester ants, which are venomous. These ants aren’t actually a requirement of the horned lizard’s diet and yet they are specialized to eat them. The horned lizard’s blood plasma binds to the venom, which neutralizes its toxicity and the resulting compound may be what deters these canines.

Now that we know how horned lizards are capable of this type of defense and how they most likely make their blood so undesirable, what is it about this chemical that is so appalling to these predators? It appears that the target area of the blood is the mouth since the horned lizard only squirts the blood when the canine begins to bite down on its head. This suggests that it may be the taste of the blood that prevents the horned lizard from becoming that coyote’s tasty snack.

The horned lizard’s ability to squirt blood at canines to prevent their untimely death is truly amazing and complex and there is still much to learn about it. Their ability makes me wonder how many other cool anti-predator adaptations there are out there in the animal and even the plant kingdom! Below is a video that will allow you to appreciate the full effect of this awesome defense strategy, enjoy!




References:

Heath, J.E. 1966. Venous shunts in the cephalic sinuses of horned lizards. Physiological Zoology 39(1): 30-35.Middendorf, G.A. and Sherbrooke, W.C. 1992. Canid elicitation of blood-squirting in a horned lizard (Phrynosoma cornutum). Copeia 1992(2): 519-527.

Middendorf, G.A. and Sherbrooke, W.C. 1992. Canid elicitation of blood-squirting in a horned lizard (Phrynosoma cornutum). Copeia 1992(2): 519-527.

Middendorf, G.A. et. al. 2001. Comparison of blood squirted from the circumorbital sinus and systemic blood in a horned lizard, Phyrnosoma cornutum. The Southwestern Naturalist 46(3): 384-387.

Middendorf, G.A. and Sherbrooke, W.C. 2004. Responses of kit foxes (Vulpes macrotis) to antipredator blood-squirting and blood of Texas horned lizards (Phrynosoma cornutum). Copeia 2004(3): 652-658.

Sherbrooke, W.C. 1992. Chiricahua Mountains Research Symposium. Horny “toad” tales from the Chiricahua mountains as, told by a biologist. Southwest Parks and Monuments Association, Tuscon, AZ. 78-80.

Monday, October 6, 2014

The Biology of Nagging

A female pied flycatcher can't feed herself sufficiently
while she incubates her eggs and newly-hatched
chicks. Photo by Alejandro Cantarero.
I have been blessed with the fortune of not just having two healthy and happy babies, but being able to spend much of the spring and summer nurturing them and watching them develop and grow. But it has not been all roses: their smiles beam through the fog of my sleep deprivation and exhaustion. Their tears are met with my own. Our clothes are stained in a rainbow of bodily fluids. Now I am back at work trying to remember how my life used to be and how to meet my obligations to countless people, all while trying to keep up with the ever-changing needs of my daughters. Luckily, I am not alone. The girls have a rotating schedule with their grandparents one day, with their dad another, at daycare for a few days, and with me on weekends and evenings. But as the expectations on me grow heavier, I find myself pushing my husband harder to do more with the girls and around the house. Now it seems like every time I open my mouth, I am accused of “being a nag” and “for no reason” no less. The truth is, nagging has a deep biologically-based reason and may even be critical to species survival.

We are not the only species that nags, although in other species these vocalizations are often called “begging signals”. Begging signals are commonly heard in bird species in which the female does most or all of the egg and chick incubation. Because these females cannot sufficiently feed themselves while ensuring the survival of their brood, their male partners need to spend extra time foraging for the females in addition to foraging for the chicks and themselves. There is an inherent conflict between how mated males would prefer to spend their time (feeding themselves, maintaining their dominance status, and flirting with females) and how their female partners want them to spend their time (providing as much as possible for the family). The male response to this conflict is often to see how little he can get away with contributing while he sneaks off to spend his time as he wishes. The female response is to produce loud, juvenile vocalizations and gestures until he brings food to the nest. Is this really necessary though? Maybe she is just being manipulative to try to get him to do more than he really needs to.

Alejandro Cantarero, Jimena López-Arrabé, Antonio Palma, and Juan Moreno from the National Museum of Natural Sciences in Madrid, Spain and Alberto Redondo from the University of Córdoba in Spain set out to test whether the begging signals made by female pied flycatchers were an honest signal of need or were just obnoxious melodrama. They predicted that if the females’ begging calls were an honest reflection of how much help they needed, then begging calls would increase as energy needs increase.

The researchers studied 71 pied flycatcher nests in a forest in central Spain. Behaviors were observed by nest-mounted video cameras five days after the females finished laying their clutches of eggs. Two days later, each female was caught and measured, fitted with an identifying leg band, and had her wings clipped. About half of these females had their primary feathers clipped at the base to impair their ability to fly (these females are called the “handicapped” group). The other half had their primary feathers clipped at the tip so that their ability to fly would not be affected (these are the “control” females). When the females were released, they all returned to their nests. Their behaviors were measured again three days later.

Females in the handicapped group lost weight and begged significantly more after their wings were clipped, whereas the control females did not. This suggests that females are adjusting their begging rates to accurately reflect their needs. Furthermore, male partners of the handicapped females fed their partners more after the wing-clipping, whereas the male partners of the control females did not. This shows that the males are responding to either their partners’ increased begging or increased need or both. Revealingly, the amount that females begged was positively correlated with the amount that the males fed them, even when the researchers statistically controlled for whether their wings were clipped or not. This means that males were feeding females more because they begged more (and not simply because they needed more, which was also true).

video
This nagging female gets exactly what she needs.
Video by Alejandro Cantarero.

So, at least among pied flycatchers, females don’t “nag for no reason”, but because they genuinely need the help to keep their bodies and families healthy and safe. And males respond to the calls for help by increasing their contributions. But the graph that shows that males feed females more because they beg more also reveals that males would not help enough if females did not beg enough. Nagging is an adaptive strategy that females must engage in to meet the needs of the family.

Is someone nagging you too much? If we are like our pied flycatcher friends, than if you meet that person’s needs, the nagging should stop.

Want to know more? Check this out:

Cantarero, A., López-Arrabé, J., Palma, A., Redondo, A., & Moreno, J. (2014). Males respond to female begging signals of need: a handicapping experiment in the pied flycatcher, Ficedula hypoleuca Animal Behaviour, 94, 167-173 DOI: 10.1016/j.anbehav.2014.05.002

Friday, February 28, 2014

Animals That Have Twins

Here are a few animals that have twins:

Image by Michael Gabler at Wikimedia.
Common marmosets:














Image by David O at Wikimedia.
Anna’s hummingbirds:














Image by Legionarius at Wikimedia.
Evening bats:














Image by Jerome66 at Wikimedia.
Leopard geckos:















They're so tiny! And yes, they held hands the moment they met.
Me!

You may have noticed my lack of posting as of late. It turns out, my twin daughters decided to make their appearance earlier than expected. Needless to say, I have had my hands quite full with this new and awesome role and I will be taking a bit of a maternity leave from The Scorpion and the Frog. But don’t worry; I will be back with more stories of the weird and wonderful world of animals next fall.

Wednesday, January 22, 2014

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

Wednesday, January 15, 2014

Caught in My Web: The Secret Lives of the Animals Around Us


Image by Luc Viatour at Wikimedia.

Most of us are surrounded by animals that we take for granted every day. We see them sleep and eat and clean themselves, and then sleep again. But our pets and yard-critters have secret and interesting lives. This week in Caught in My Web, we explore some of the lesser-known secrets of the animals around us.

1. Your dog poops in alignment with the Earth’s magnetic field.

2.  Your cat is just using you.

3. Some of the fish in your fish tank may change sex:


4. The birds at your birdfeeders have personalities, and some are liars.

5. Squirrels are the masters of… well, just about everything.

Wednesday, January 8, 2014

Freezing the Winter Away

The clutches of the Polar Vortex are finally releasing its grasp on us and we can be thankful for our home heating, our layers of warm clothing, and most of all, our bodies’ abilities to generate heat. But it is times like these that make me wonder about our friends that live outside year-round… especially those that don’t generate most of their own body heat. How do they survive these periods of intense cold? There are several species of North American frogs that have an unusual trick up their sleeve: They freeze nearly solid and still live to see the next spring.

This picture of a wood frog is by Ontley at Wikimedia Commons.
Frogs are ectothermic, meaning they take on the temperature of their surroundings rather than generate their own body heat. This introduces some intriguing questions about how these species even exist in northern climates that experience freezing temperatures every year. When various North American frog species (including wood frogs, spring peepers, western chorus frogs, and a few gray tree frog species) take on freezing winter temperatures, they actually allow their bodies to freeze nearly solid. For most species, this would be a deadly approach: a frozen circulatory system would halt the delivery of oxygen to cells, which require oxygen to generate the energy they need to do just about everything a cell does. Furthermore, jagged ice crystal edges could rupture the cells they are inside. Dead cells lead to dead organs, which in turn lead to dead animals. These freezing frogs have found the secrets to freezing without killing their cells.

The first secret of the freezing frogs is to spend the winter snuggled in the leaf litter below the snow. This environment insulates and protects the frogs from the deadly wind chills we have been facing for the last several days.

The second secret of the freezing frogs is a creative use of colligative properties. Colligative properties are properties of solutions that depend on the ratio of the number of liquid molecules to the number of molecules of stuff dissolved in that liquid. One of those properties is called freezing point depression: The temperature at which a liquid will freeze can be lowered by adding particles to it. (This is why salt is spread on roads in the winter). A critical component of the freezing frog strategy is for the liver to produce massive amounts of glucose in response to the start of freezing. This glucose is pumped throughout the body, which lowers the freezing point of all of the organs.

A third secret of the freezing frogs is the use of ice nucleating agents: proteins that actually encourage freezing. This may seem counterintuitive, but remember that ice crystals inside cells can cause them physical damage. By having a high concentration of ice nucleating agents in the fluid between the cells, this ensures that ice first forms in the spaces surrounding the cells. When ice forms, the ice crystals are made of only water molecules, which draws water out of the solution and leaves behind a higher concentration of other stuff (like glucose) in between the cells. The high concentration of glucose between the cells draws water out of the cells and into that space. This additional water also freezes. In the end, the cells are chock-full of particles, lowering their freezing temperature, and are surrounded by ice, which insulates the cells. Thus, this process of ice formation around the cells prevents ice from forming inside the cells.

A fourth secret of the freezing frogs is a metabolic shift. Most animal cells rely on oxygen to produce the energy they need to support their demands. But cells have ways of producing energy without oxygen too. These ways are not very efficient, but are useful when there is not enough oxygen available to meet demand (such as when a seal dives or a cheetah reaches burst speed). When freezing frogs start to freeze and oxygen delivery to the cells slows and eventually stops, their cells shift from an oxygen-reliant system of energy creation to an oxygen-independent system of energy creation. Additionally, freezing organs do less and don’t require as much energy anyway, so they can continue functioning at low levels for a long time if the freezing spell is prolonged.

When the environment warms up (as forecasters promise will happen), the body temperatures of these frogs raise and body fluids slowly become liquid again. The heart starts to beat again within hours of the start of thawing and oxygen can again be delivered around the body. The delivery of oxygen-carrying blood helps the rest of the organs return to their normal functions.


There are still many secrets of these freezing frogs left to uncover. Maybe you’ll be the one to do it… once we thaw out a bit.

Want to know more? Check these out:

1. Storey, K.B. (2004). Strategies for exploration of freeze responsive gene expression: advances in vertebrate freeze tolerance Cryobiology, 48, 134-145 DOI: 10.1016/j.cryobiol.2003.10.008

2. Layne, J.R., & Lee, R.E. (1995). Adaptations of frogs to survive freezing Climate Research, 5, 53-59 DOI: 10.3354/cr005053

Wednesday, January 1, 2014

Metabolism and Body Size Influence the Perception of Movement and Time

Zoetropes like this one have been used
for almost 2000 years. If you look in the
slits from the side, the image appears to
be animated. Image by Andrew Dunn
at Wikimedia Commons.
When we watch TV or a movie, we are essentially watching a series of still images presented in rapid succession… so rapid, in fact, that we perceive them to be a single moving image. The ability of movie-makers to convince us that still images are fluid in time is based on our physiology. Specifically, moving-pictures, as they were once called, rely on our critical flicker fusion frequency (CFF), the lowest speed at which we perceive a flashing light source to be a constant light. But we don't have our CFF so we can enjoy movies and TV; it came about from our need to identify and track moving objects.

The ability to identify and track moving objects is critically important for finding and catching prey, avoiding predators, and finding mates. It is these visual abilities that rely on an animal’s CFF. An animal with a low CFF will miss many visual details, like watching your TV with a fast-forward function that jumps ahead 15 seconds at a time. An animal with a high CFF will see all the details that happen in between with a fine-time-scale resolution. But if having a high CFF conveys such an advantage, why don’t all animals have a high CFF?


This week at Accumulating Glitches I talk about how an animal's size and metabolism can influence how it sees the world. Check it out here.

And to learn more, check this out:

Healy, K., McNally, L., Ruxton, G.D., Cooper, N., & Jackson, A.L. (2013). Metabolic rate and body size are linked with perception of temporal information Animal Behaviour, 86, 685-696 DOI: 10.1016/j.anbehav.2013.06.018

Wednesday, December 25, 2013

Miss Behavior’s Picks of 2013


Image from freedigitalphotos.net.

2013 is quickly drawing to a close and we find ourselves in a time of reflection and reminiscences of the last twelve months. Science blogging continues to grow and our many talented and experienced science writers are finding themselves joined by a new cohort of young energetic writers bringing new perspectives. This is an exciting international community of passionate thinkers, debaters, and science communicators. These are my picks for The Top 5 Animal Physiology and Behavior Blog Posts of 2013 (not including The Scorpion and the Frog posts and in no particular order).

On the new blog, Viruses 101, Julia Paoli, a high school student and talented science writer discusses a scientific estimate of how many unknown viruses lurk within our fellow mammals in Mammals Harbor At Least 320,000 Undiscovered Viruses.

Natalie Wolchover at Quanta Magazine pondered the value of partial honesty among animals from a game theory perspective in Hunger Game: Is Honesty Between Animals Always the Best Policy?

We all carry communities of microbes within our bodies that have now been found to be involved in our health and behavior in ways we never previously imagined. In Inspiring Science, Sedeer el-Showk talks about research linking differences in our microbiomes to hormone levels and disease resistance in Sex, Hormones, and the Microbiome.

On EveryONE by PLOS Blogs, Alex Theg tells the story of a jumping spider species that uses multiple deceptive tactics. Read about the spiders that use visual mimicry to trick predator spiders and chemical mimicry to trick predator wasps in Ant-Mimicking Spider Relies on a “Double-Deception” Strategy to Fool Different Audiences.

Felicity Muth discusses animal homosexuality in her blog, Not Bad Science. Check out her article Homosexuality in Female Beetles, and What We Can Learn from It.

Merry Christmas and stay curious!

Wednesday, December 18, 2013

What Does the Fox Say?

Image by Rotfuchs at Wikimedia.
In early September, two brothers that host a popular late-night talk show in Norway released a music video to promote their show’s season premiere. Those brothers form the comedic duo called Ylvis, and the song: “What Does the Fox Say?”. A complete surprise to the Ylvisåker brothers (their last name), who designed their video as a comedic music video flop, their video went viral. It spent three consecutive weeks as number 6 on Billboard Hot 100 and is quickly approaching 300 million views in just over three months!

The premise of the song is that there are a number of animals whose sounds everyone knows, but the fox stumps us. As their lyrics go:

Dog goes woof, cat goes meow.
Bird goes tweet, and mouse goes squeak.
Cow goes moo. Frog goes croak, and the elephant goes toot.
Ducks say quack and fish go blub, and the seal goes ow ow ow.
But there's one sound that no one knows...
WHAT DOES THE FOX SAY?

…And then it gets weird as they propose their thoughts on what sounds foxes make:


The funny thing is, it’s not that hard to find out what sounds foxes really make. Although they may not be among the common farm and zoo animals that make it into our children’s toys and books to teach us all about the world of animals, fox vocalizations have been studied by scientists for years. Strangely enough, our comedic duo was not that far off with their “Jacha-chacha-chacha-chow!” guess, which is similar to the fox gekkering call used in aggressive interations.


“The Fox” video (as it has come to be known) has spawned countless spoofs in the last few months. As with most internet spoofs, most are pretty lame, but there are a few gems. My favorite, created by some talented Harvard Medical School students, addresses the equally perplexing question “What Does the Spleen Do?” (Which we also know the answer to. Check out the end of the video for the true answer).