Category Archives: Fun Fact

Want to find life on Mars? There’s a catch…

There has been a lot of talk recently about “getting our ass to Mars” (to phrase it as Dr. Buzz Aldrin has on social media). Whether it’s Elon Musk talking about the new SpaceX plan to colonize Mars (first passengers might be taking off by 2024, start saving!), the record low global sea ice levels here on Earth, or just the results of recent elections (Fig. 1) — people have been thinking about extraterrestrial adventures.

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Figure 1: Google Trends for “I dont want to live on this planet anymore” searches. November 8th 2016 was election day in the USA.

This gives me a good excuse to share one of the most interesting challenges we face when finding a landing spot on the Red Planet.

Surely, when sending a Rover to Mars in search of life, like we will in the year 2020, we would want to send it to the place that is the most likely to harbor life (or has the ingredients necessary for life according to our understanding of what life requires here on Earth). Right? This is probably true for when we want to send humans there as well— the more similar to Earth, the higher our chances of survival. But, there is a catch.

The site we think would be the most likely to harbor life would also be the most likely to be infected with life from Earth­— life that could outcompete the local Martians and lead to a planet-wide extinction. We (or, our microbes) could be the classic Hollywood alien invaders who annihilate local life in the search for resources.

Now, someone who has never read this blog or sat through a microbiology class might think “Hey, easy solution, just sanitize things before takeoff! Plus, the harsh conditions of space travel will get rid of any pesky stowaways.” Not so easy.

Firstly, let’s pretend for a moment that our bodies are not harboring a complete ecosystem of microbial life, and that somehow we can guarantee that humans and their waste never contact the surface of Mars. Still, microscopic life is everywhere on Earth. And I mean everywherelike 800 meters below the ice in an Antarctic subterranean lake everywhere. I think it is safe to say that some of this life will contaminate anything we send to Mars. In fact, 65 species of bacteria were found stowed away on the 2012 Mars Curiosity Rover.

Secondly, some microbial Earthlings are extreme. And I mean extreme— like proliferating at 403,627 × Earth’s gravity extreme. Like living in a liquid asphalt desert extreme. And yes, like living outside in space for 1 and a half years extreme.

So, the possibility of microbial stowaways surviving to mars is real.

And, of course, NASA knows this. In fact, they have a whole Office of Planetary Protection devoted to, among other things, “Avoiding the biological contamination of explored environments that may obscure our ability to find life elsewhere – if it exists; …”. The United Nations knows this as well. The Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies includes:

States Parties to the Treaty shall pursue studies of outer space, including the moon and other celestial bodies, and conduct exploration of them so as to avoid their harmful contamination and also adverse changes in the environment of the Earth resulting from the introduction of extraterrestrial matter and, where necessary, shall adopt appropriate measures for this purpose.

The possibility of contaminating planets that may harbor life presents a real ethical dilemma for robotic and human colonists. Should we search out life on a planet surface and also risk infecting the planet with Earthling microbes? Should we colonize another planet if it means we may destroy the local inhabitants? I’m not going to try and answer those questions here, but feel free to leave thoughts here or tweet them to me.

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Fun Fact about your diet…

Spoiler alert: I usually start my seminars by talking about how we are all in a continual flux of our constituent cells. Don’t tell me that “people never change”… yes, they do, in fact every day a huge chunk of every person dies and is reborn. For instance, perhaps 84% of our cells are red blood cells, and each one of those cells only lives about 100-120 days (meaning that 2.4 million new cells need to be produced every second)! Not only that, our entire intestinal epithelium is completely renewed every few days, and we lose (and gain) about a Billion (Carl Sagan emphasis added here) cells in our small intestine every 20 minutes.  Woah.  OK, … so what happens to the cells that “leave” our intestines? They enter the part of the gut where the “food” goes. So, do we eat them? Do we eat our own cells? Are we constantly, every day, digesting ourselves?

Yes.

According to the Food and Nutrition Encyclopedia, every day 25% of the protein in our diet comes from digesting our own intestinal cells! Think about that. Today, perhaps one fourth of the protein in your diet came from digesting your own flesh!

And then I can start talking about my research.

Spider Sunday is back! This week: Wolves in Your Backyard.

I have a confession. When I was young I wasn’t very kind to spiders. My behavior can likely be attributed to fear; growing up we are surrounded by imagery of spiders being dangerous and alien. We fear what we don’t understand. The internet says Marie Curie once said “Nothing in life is to be feared, it is only to be understood. Now is the time to understand more, so that we may fear less.” And it’s true, the more I learned about spiders the less I squashed them. Now that I’m older, and a biologist, and living in Florida (read: constantly surrounded by giant spiders), I see spiders as fascinating, useful, and largely innocuous. And I’m on a mission to spread this view in order to gain back all the biology-karma I lost squashing spiders in my childhood. So, here are some neat facts I just learned after to a recent encounter.

Storytime. The other night I was outside enjoying the (relatively) cooler Floridian night and getting some work done. Suddenly I glimpsed a familiar shape darting towards the leg of my chair. A few inches long, but too meaty and agile to be an orbweaver or banana spider, I knew it had to be a wolf spider. So, I jumped up and reached for my phone and rushed to snap a picture before she retreated. When the flash went off I was greeted with a surprise…

Proud Wolf Spider Momma

Proud Wolf Spider Momma

Reflections. Reflections from eyes. But wait, why are there reflections coming from the spider’s abdomen?

Woah. Cool! Ok, so now I know that wolf spider’s eyes are reflective, just like I’ve seen (and posted about) before in Golden Orb-weavers…

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Golden Orb-weaver, La Chua Trail, Gainesville FL.

This is very similar to the reflections we’ve all seen before when shining a light towards certain mammals at night, such as cats or raccoons.

Raccoon hanging out behind UF's Science Library, Gainesville FL.

Raccoon hiding out behind UF’s Science Library, Gainesville FL.

So, what’s going on here? By reflecting light back through the retina there is more light available to the photoreceptors- enhancing night-vision. In vertebrates this is accomplished by the tapetum lucidum, or “bright tapestery” in Latin, a thin tissue membrane in the back of the eye. It looks like the tapetum has evolved independently in invertebrates and vertebrates, and actually exists in several invertebrate taxa including scallops, crustaceans, scorpions, and dragonflies. The tapetum in invertebrates consists of parallel strips of reflective guanine crystals- the same type of crystals that give fish their shiny metallic skin and allow chameleons to shift their skin color.

Want to see it for yourself? Go outside at night and shine a bright light into the grass. Those hundreds of reflective dots shining back? Wolf spiders looking at you. But fear not, for now you understand more. Just wear shoes.

(and share your cool spider pictures with me!)

Dragonflies are awesome.

Alright, so my wife and I both think dragonflies are really cool. We never really thought about exactly why we think this, it’s just this inherent neatness about them. Maybe it’s how they hover like brightly colored silent helicopters and then quickly dart about like… I don’t know, some sort of alien spacecraft. And, unlike some of our other backyard insect friends (I’m talking about mosquitoes and red imported fire ants, both of which seem to have an affinity for my skin in particular), dragonflies don’t bother us.

This last weekend I was fortunate enough to have a dragonfly interaction that got me falling down the wikipedia rabbit hole learning about our flying friends, so I figured I’d share some of what I found here. First, for the fateful interaction:

I was grilling up a batch of beer in preparation for the summer…

You read that right. Cannataro’s Brewery Summer Saison will go on tap June 2015.

… and I was joined by a male blue dasher!

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He hung out for a while, flew to different perches, and even let me get a few close-ups.

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Smiling for the camera. Which, by the way, was just my cell phone (galaxy s4).

Eventually my wort was ready to start cooling and he was done patrolling the garden so we exchanged our goodbyes and went our separate ways.  Little did I know the carnage that was awaiting me the next morning. Warning, dear reader, the next image is graphic.

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My dragonfly friend had been decapitated! By one of his own! Well, kind of. That new, green, living dragonfly is (I believe) a female eastern pondhawk. After I took that picture she flew off, taking the body with her, leaving just his head as evidence. Woah. Talk about cool backyard biology! Down the wikipedia rabbit hole I went. Time for some rapid fire fun dragonfly facts.

Dragonflies have been on Earth in pretty much their present form for over 300 million years. In fact, the largest insect to ever exist was an ancient dragonfly (with an estimated wingspan of 28 inches!). They can spend years in their underwater nymph form, which has extending and retractile lower jaws (remind you of any alien characters?) and can feed on vertebrates (small fish, tadpoles) and mosquito larvae (thank you).

The adults enjoy mosquitoes as well (told you they were awesome).

The nymph crawls out of the water and transforms directly into the adult in a process called ecdysis. They have a unique mating system where the male grabs the female behind her head with the claspers at the end of his abdomen and they form a heart-shaped mating pair. Their wings are self-cleaning and water repellant due to the lotus effect. I can go on and on, but if you want to learn more you should check out this video:

So next time you look at a dragonfly think about how you’re looking at the 300 million year old body plan of a ruthless killing machine with a 95% hunting success rate. Dragonflies are awesome!

 

January 2015 fun facts

Woah, I’m way backlogged on blog posts! Don’t worry, I have some cool stuff in the works and I’ll share soon. In the meantime check out some of the science I’ve been starting my classes off with this month.

Aging research: blood to blood – scientists can splice animals together by creating a wound in each animal and sewing them together- their natural wound healing mechanisms join their bodies and their blood (it’s called parabiosis)! If you splice an old animal to a young one the tissue in the old animal gets “rejuvenated” by the young animal’s blood.  Sounds like the premise for a horror movie.

Scientists have discovered a new antibiotic that kills pathogens without detectable resistance.

Scientists have discovered that tumor cells can actually acquire previously lost DNA (in this case mitochondrial) from “normal” cells, and that the newly acquired DNA restores missing function. Think about that. Somatic cells (or cells that were once deemed somatic but now have become tumor cells) can horizontally transfer DNA. Biology textbooks get rewritten every day.

And, of course, I can’t introduce metabolic scaling and not discuss the invariance of heartbeats.

Enjoy!

Mind controlling parasites- how sci-fi are zombies anyway?

 

Halloween weekend is drawing to a close, and as I type this (looking out a coffee shop window) I can still see the zombie makeup on the faces of those passing by. It’s understandable why the whole zombie thing can be pretty terrifying. In the movies the protagonist usually watches their once fully autonomous friends and loved ones fall prey to some microscopic parasite and become a mindless vessel, obeying the will of their neural captors, tasked with ensuring the survival of the parasite and oblivious to their own health. Good thing it’s science fiction! Right? Well, anyone studying parasitology can tell you that in some cases it’s less fiction and more science.

Whenever I teach the lab on species interaction I always spend a good bit of time on mind controlling parasites. First off- they’re just cool. Plus, there’s a lot of captivating videos out there! One of my favorite being:

(p.s. larva emerging from a caterpillar body below, viewer discretion advised!)

Great music and sound effects aside, it’s always interesting and sort of mind-blowing to see the caterpillar actively defend the larva that just busted through its skin. It really gives you a sense of just how possessed an organism can become at the whim of a parasite. Another zombie-state-inducing parasite infects snails:

And another favorite, the inspiration for the zombie-survival game The Last of Us, infects and alters the behavior of entire forests full of insects:

 

Ok, so mind controlling parasites might actually be all around us, but at least they only infect invertebrates. Right?! Well, no.

Rats have a natural (and understandable) aversion to cats. When they smell cat urine they feel fear and head in the other direction. However, rats infected with the protozoan Toxoplasma gondii, which only reproduces in the cat intestine, are actually drawn to cat urine. The parasite hijacks the sexual arousal pathway in the rat brain, and instead of feeling fear the rat feels sexual attraction to the cat odor. So, just like the snails in the video above, the rats search out their natural predators for the benefit of their parasite.

 

Ok, so mind controlling parasites can infect and manipulate the behavior of mammals as well. But, certainly humans, with their giant and complex brains, don’t have to worry about being influenced and controlled by the whims of a tiny microscopic organism. Right?! Well…

I have a habit of bringing up the universe that exists within multicellular organisms. It’s easy to think of this as a one way interaction- a large organism goes about their business and the little organisms tag along for the ride. But the survival and wellbeing of the microbiome is extremely important- so important that hosts even synthesize food for their microbiome during periods of illness to ensure that their microbial friends stay happy.

Is it possible that some of our microbial friends could be manipulating our behavior for their benefit? Some scientists have recently suggested that might be the case- we might be at the whims of a microbial puppet master. More research is needed to test these hypotheses, but I look forward to the day where taking a microbe-filled pill can change my appetite for the better and bolster my microbiome.

Outside of our bacterial microbiome, we also house a vast virome. Research published in PNAS this week has shown that humans can be infected with an algal virus, and this virus was associated with a 10% decrease in performance on visual processing exams. Additionally, mice infected with the virus took about 10% longer to navigate a maze and explored 20% less.

So, maybe we’re not so autonomous after all. Spooky! Happy Halloween!

The Ultimate Sunset

April 15, 2014 03:49am

April 15, 2014 03:49am

I took the telescope out during April’s lunar eclipse…

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April 15, 2014 02:23am

… and had a really amazing time. At first it was just the mosquitoes, the clouds, a cool drink, and myself, but after a while people started pouring out of their apartments to see the show.

April 15, 2014 01:18am  Staying homed in with the laser finder, waiting for the clouds to leave.

April 15, 2014 01:18am
Staying homed in with the laser finder, waiting for the clouds to leave.

So of course I invited them all over to watch through the telescope. By the end about 10 strangers were standing around watching the bloodmoon and discussing human history, space, science, etc.

April 15, 2014 12:54am

April 15, 2014 12:54am

Imagine what it would be like not knowing anything about the true nature of eclipses and, one seemingly random and unpredicted night, the full moon started disappearing- and then turned blood red. What a sign!

Luckily, we live in a time where humans have walked on the moon, so we do know a bit about it. So, why does the moon turn red?

Well, what color is the sky? (class shouts blue!) If the sky was blue, then how come images of the Earth from space aren’t of a blue ball? Or we don’t normally see a blue moon and blue stars? The sky appears blue because our atmosphere scatters blue wavelengths of light more than other wavelengths of light. When the sun is low in the sky, like during a sunset, the light reaching your eyes has passed through much more atmosphere than when the sun is high in the sky, causing most of the blue light to be scattered out already (for people who are experiencing noon elsewhere). So all that’s left in the light when it reaches your eyes during a sunset are the yellows and reds.

During a lunar eclipse the moon is behind the Earth, with the sun on the other side. The light reaching the moon has passed through the edges of the Earth’s atmosphere, causing a projection of what we see in a sunset to fall on the face of the moon. It’s the ultimate sunset!

 

Open question: Alright, after reading some Wikipedia articles on diffuse sky radiation and the like… I have a question. If our atmosphere scatters blue light, and images of the Earth from space are possible because sunlight is being reflected off of the Earth’s surface and into a camera, how come the Earth doesn’t appear reddish? You know, since the sunlight has passed through the atmosphere twice (down to Earth and back up to space?)

 

p.s. here’s a paper from 1868 “On the blue colour of the sky, and the polarization of light