Vampires!

Photo by Alejandro Lunadei at Wikimedia.

A reposting of an original article from October 19, 2015

Vampire mythologies have been around for thousands of years, terrifying the young and old alike with stories of predatory bloodsuckers that feed on our life essences. You may not believe in vampires, but they are all around us. In fact, you may have some in the room with you right now! You just don’t notice them because they are not human, or even human-like.

Vampires feed on the blood of their victims in order to sustain their own lives. This phenomenon, called hematophagy, is more common than typically occurs to us at first. Just take mosquitoes and ticks as examples. Once we’ve opened our minds to the idea of bloodthirsty arthropods, we quickly think of many more: bedbugs, sandflies, blackflies, tsetse flies, assassin bugs, lice, mites, and fleas. In fact, nearly 14,000 arthropod species are hematophages. We can expand our thoughts now to worms (like leeches), fish (such as lampreys and candirús), some mammals (vampire bats), and even some birds (vampire finches, oxpeckers, and hood mockingbirds). We’ve been surrounded by vampires our whole lives, we just never sat up to take notice!

Hematophagous animals are not as scary as mythical vampires, in part because they don’t suck their victims dry – they just take a small blood meal to sustain their tiny bodies. Hematophagy is not, in itself, lethal. However, the process of exposing and taking the blood of many individuals transmits many deadly diseases, like malaria, rabies, dengue fever, West Nile virus, bubonic plague, encephalitis, and typhus.

Because blood feeders do not kill their meals, feeding can be even more dangerous for them than for traditional predators. As a result, many hematophagous animals have developed a similar toolkit. Many have mouthparts that are specialized to work as a needle or a razor and biochemicals in their saliva that work as anticoagulants and pain killers. Their primary skill, however, is their stealth: they can sneak up on you, eat their meal, and be home for bed before you even notice the itch.

Although a few species, like assassin bugs and vampire bats, are obligatory hematophages (only eat blood), most hematophages eat other foods as well. Somehow, Dracula is not quite so intimidating when you imagine him drinking his morning fruit juice, like many mosquitoes do.

Why drink blood in the first place? Blood is a body tissue like any other, and it contains a lot of protein and a variety of sugars, fats and minerals, just like meat. However, blood is mostly water, which means that a blood meal contains less protein and calories than the same weight of meat. Because you need to consume so much more to get enough protein and calories out of a meal, large animals and animals that generate their own body heat can't usually rely on blood meals alone. So much for human-like vampires that only live off the blood of their victims.

A deadly vampire spreading malaria. Photo by the CDC available at Wikimedia.

So true vampires are everywhere, but they are small, take small blood meals, don't generally kill their hosts, and often use blood to supplement their other meals. Not so scary any more, are they? ...Although, about 3.2 billion people (about half the world's population) are at risk of contracting the deadly disease, malaria, from these bloodsuckers... so maybe you aren't scared enough. Bwaa-haha!

Vampires!

Photo by Alejandro Lunadei at Wikimedia.

Vampire mythologies have been around for thousands of years, terrifying the young and old alike with stories of predatory bloodsuckers that feed on our life essences. You may not believe in vampires, but they are all around us. In fact, you may have some in the room with you right now! You just don’t notice them because they are not human, or even human-like.

Vampires feed on the blood of their victims in order to sustain their own lives. This phenomenon, called hematophagy, is more common than typically occurs to us at first. Just take mosquitoes and ticks as examples. Once we’ve opened our minds to the idea of bloodthirsty arthropods, we quickly think of many more: bedbugs, sandflies, blackflies, tsetse flies, assassin bugs, lice, mites, and fleas. In fact, nearly 14,000 arthropod species are hematophages. We can expand our thoughts now to worms (like leeches), fish (such as lampreys and candirús), some mammals (vampire bats), and even some birds (vampire finches, oxpeckers, and hood mockingbirds). We’ve been surrounded by vampires our whole lives, we just never sat up to take notice!

Hematophagous animals are not as scary as mythical vampires, in part because they don’t suck their victims dry – they just take a small blood meal to sustain their tiny bodies. Hematophagy is not, in itself, lethal. However, the process of exposing and taking the blood of many individuals transmits many deadly diseases, like malaria, rabies, dengue fever, West Nile virus, bubonic plague, encephalitis, and typhus.

Because blood feeders do not kill their meals, feeding can be even more dangerous for them than for traditional predators. As a result, many hematophagous animals have developed a similar toolkit. Many have mouthparts that are specialized to work as a needle or a razor and biochemicals in their saliva that work as anticoagulants and pain killers. Their primary skill, however, is their stealth: they can sneak up on you, eat their meal, and be home for bed before you even notice the itch.

Although a few species, like assassin bugs and vampire bats, are obligatory hematophages (only eat blood), most hematophages eat other foods as well. Somehow, Dracula is not quite so intimidating when you imagine him drinking his morning fruit juice, like many mosquitoes do.

Why drink blood in the first place? Blood is a body tissue like any other, and it contains a lot of protein and a variety of sugars, fats and minerals, just like meat. However, blood is mostly water, which means that a blood meal contains less protein and calories than the same weight of meat. Because you need to consume so much more to get enough protein and calories out of a meal, large animals and animals that generate their own body heat can't usually rely on blood meals alone. So much for human-like vampires that only live off the blood of their victims.

A deadly vampire spreading malaria. Photo by the CDC available at Wikimedia.

So true vampires are everywhere, but they are small, take small blood meals, don't generally kill their hosts, and often use blood to supplement their other meals. Not so scary any more, are they? ...Although, about 3.2 billion people (about half the world's population) are at risk of contracting the deadly disease, malaria, from these bloodsuckers... so maybe you aren't scared enough. Bwaa-haha!

Gut Feelings

This boy may be influencing who he will marry when
he grows up. Photo by Orrling at Wikimedia Commons.

Animals (including humans) are swarming with microorganisms both on and in our bodies. Humans harbor so many different microorganisms that we have over 150 times more microbial genes than mammalian genes, and it is reasonable to suspect that this scenario is similar for most animals. But before you run to soak in a tub of hand sanitizer, you should realize that many of these microorganisms are actually beneficial to the health of both your body and your mind. Although this field is still very much in its infancy, we have found that the microbes that live in digestive tracts in particular significantly influence their host animal’s behaviors. This connection between our digestive communities and our behaviors has been termed the microbiota–gut–brain axis.

Much of the early research on the microbiota-gut-brain axis was done using specialized mice that have never been exposed to any bacteria. You may think this sounds like a healthy lifestyle, but these so-called germ-free mice have all kinds of health and behavioral problems. They often have digestive difficulties and high levels of anxiety, symptoms common of people with irritable bowel syndrome (IBS). They also typically have deficits in social behavior and increased repetitive behaviors. Similar to autism-spectrum disorders and obsessive compulsive disorder (OCD), these behavioral problems are more likely to occur in males than in females. When faced with a challenge, many struggle with solving the problem and show a higher tendency to give up, symptoms common in patients with depression. Interestingly, simply feeding germ-free mice some species of Bifidobacteria and Lactobacilli bacteria (similar to bacterial strains found in different brands of yogurt) can reduce symptoms of anxiety, depression, cognitive difficulties, autism, and OCD. This has led to a boom in biomedical research on the benefits of probiotics (that contain microbes that live in our guts) and prebiotics (that contain things that the microbes in our guts eat).


Yogurt bacteria. Photo by Josef Reischig at Wikimedia Commons.

These gut microbes don’t just help animals maintain their physical and mental health, they are also involved in complex social behaviors. For example, fruit flies prefer mates that grew up eating the same diet that they grew up eating. However, if they are treated with antibiotics, which kill the gut bacteria, they lose their mate choice preferences. If they are then treated again with microbes from their initial diet (with one Lactobacillus bacteria in particular), they gain their mate choice preferences back. This all makes me wonder, how important is yogurt to choosing the people we date and marry?

How do microbes in our guts affect our brains anyway? Although the answer to this is still mostly unknown, we know that the gut has the potential to influence the brain through multiple means, including hormone production, immune function, and even directly through specific nerves. The specific mechanisms are still being very actively researched, but it is clear that microscopic critters living in our guts likely influence our brains and behaviors in many different physiological ways.

Microbiota-gut-brain axis research is revolutionizing the way we think about health, medical treatments, behavior and even existential questions like who am I? But one thing is for sure: I’m gonna go have another yogurt.


Want to know more? Check these out:

Cryan, J., & Dinan, T. (2015). More than a Gut Feeling: the Microbiota Regulates Neurodevelopment and Behavior Neuropsychopharmacology, 40 (1), 241-242 DOI: 10.1038/npp.2014.224

Ezenwa, V., Gerardo, N., Inouye, D., Medina, M., & Xavier, J. (2012). Animal Behavior and the Microbiome Science, 338 (6104), 198-199 DOI: 10.1126/science.1227412

Caught in My Web: Ants as a Liquid, Beautiful Bees, Ant Zombies, Tumbling Spiders and More Insect Oddities

Image by Luc Viatour at Wikimedia.

For this edition of Caught in My Web, we explore all kinds of creepy crawly weirdness.

1. Ant colonies have the amazing property of being able to act both as a solid and as a liquid. IFL Science! and the New York Times highlight how the physics of ants can inspire the production of self-healing structures.

2. From Wired: This fly species invades ant brains… then pop their heads off!

3. This Moroccan spider tumbles away from danger, likely crippling the predator with laughter:

4. National Geographic shares some of the most beautiful images of bees that you will ever see.

5. This TED insect playlist includes 11 talks on everything from firefly love to robotic insects.