Sunday, May 12, 2013

Mother Nature's Underground Art Gallery

I finally finished reading Parasite Rex a few days ago.  It was an amazing book, and if you haven't read it already, you should!  As I started thinking about what to write about for today's post, I started reflecting on the last chapter of the book.  I also started thinking about why I am so intrigued by parasites and why so many other people find them disgusting.  So, I decided that rather than talk about a specific parasite today, I would blog about how I came to be a lover of things that many people consider "repulsive".

To further preface this post, I've been living at a biological field station for a little over a week.  I'll be working here all summer doing various odd jobs and being a teaching assistant for summer sessions.  In addition to being a parasitophile, I'm also an araneophile (lover of spiders).  I started collecting a few spiders after arriving here just for funzies, but now I've fallen into working on building a permanent spider collection for the station since we don't already have one here.  Over the course of four or five days, I've already collected 30 specimens representing at least 6 different families as far as I can tell.  I will be ordering a spider identification manual soon so that we can officially identify what I've collected so far.  Like parasites, spiders are creatures of great beauty, complexity, and diversity that are vastly under-appreciated by the general public. 

What is it with me and liking creatures most people are disgusted by or avidly afraid of?  I pondered this question for a very long time last night as the thought of getting a spider tattoo crossed my mind.  Why a spider tattoo?  Because it would be more than simply a thing I found interesting, it would be highly symbolic of my growth as a scientist.  You see, I haven't always loved fact, most of my life I was very much an arachnophobe.  I would squeal and stomp just like any girl would do despite being surrounded by them the majority of my childhood growing up on a farm.  I was also afraid of snakes and some of the more threatening flying insects like wasps and muddobbers.  I wasn't so keen on ants either.  But things change as we grow older, and more importantly wiser.

As a young biologist, I took a class in vertebrate zoology that made me decide I wanted to become a herpetologist (one who studies reptiles and amphibians).  I loved frogs and lizards and was even developing a fondness for turtles.  Then there were snakes.  Most people who long to be herpetologists love snakes...I was the opposite.  Snakes were the last creatures I wanted to study, but I knew that they sort of came with the territory if I wanted to be a herpetologist.  So I set out to change my fear of snakes into at the very least a mild tolerance.  I tried to handle them every chance that I got and I read up on how they worked and how to handle them safely.  In my quest for better understanding, I soon realized that many snakes were completely harmless to us humans.  I even started seeing some of these as "cute"...a word I never would have used to describe a snake in the years prior to college.  It wasn't long before snakes no longer frightened me, though I have a healthy respect for venomous ones like diamond backs (Crotalus atrox).

Later in my career I became a graduate student.  In working towards a general biology degree, I wanted to take all of the "-ology" classes I didn't get to take as an undergrad.  I filled my time with mammalogy (study of mammals), araneology (study of spiders), mycology (study of fungi), and entomology (study of insects).  I was delighted to take entomology because I wanted to learn more about butterflies and beetles...and I did.  I also learned about the dreaded wasps, bees, and ants that I had admittedly trembled in fear of before.  (I recall even locking myself in a bathroom until my now-husband came home to rescue me once because a wasp found its way into our home.)  But I wasn't about to let these little devils stand between me and getting an "A" on my insect collection.  I learned more about these terrifying creatures and I forced myself to capture some of them (though I also conned some of my friends into doing my dirty work).  As I became more knowledgeable about the complexity, diversity, and downright coolness of these creatures, my fears slowly evaporated into non-existence.  By the end of it, I was no longer afraid to approach nests of these little beasts.

Feeling confident about my ability to work with virtually any type of insect and feeling unburdened by the shackles of my former fear was intoxicating.  I didn't want to be afraid of anything that nature could throw at me anymore.  I had truly learned that knowledge is power.  Understanding something made it less scary...and the next natural step after conquering one's fear is starting to see the beauty in the biology of such magnificent creatures.  So I decided to step it up...I registered to take a class about spiders.  For an entire semester, I focused on learning about these creepy crawlers.  Just as with the metamorphosis I underwent with insects, I slowly began to shift my perspectives about spiders.  They weren't the things of nightmares...they were animals with fascinating behaviors, intricate physiology, and astounding beauty once you could appreciate them.  I came to call some of these "adorable" like the jumping spiders with iridescent chelicerae or the happy face of a crab spider.  Talk about a giant leap towards conquering my fears!

This was my most miraculous change and the experiences of that semester really started to shape how I saw both the natural world and how I viewed society in general.  These lessons made me realize that some of the most beautiful things are things you have to want to understand and you have to take the time to really get to know before you can appreciate the amazing insights they have to offer.  This applies to people as well.  I won't go too deep into my sociopolitical views as you aren't here to read about those viewpoints...but I will say that understanding diversity in nature really shifts the way we see diversity amongst human populations.  We start to see that people who are different from us have a place and a purpose in our society.  We start to understand that if everyone was the same, our societal ecosystem would be dull and also...more importantly...would not be healthy.  We need diversity in society just as any ecosystem needs more than one type of flower or more than one species of insect.  Diversity keeps things interesting, beautiful, vibrant, and healthy.  Diversity = Progress from a human societal perspective as well as from a biological perspective.

By this time in my career I had discovered the sweet love that dare not speak its, I'm not a lesbian...I'm talking about becoming a parasitophiliac.  The world doesn't always see parasites in the best of fact, the opposite is more often true.  However, I had begun to see the beauty in another group of creatures most people found disturbing and even disgusting.  I had fallen for stories of bizarre life cycles and unimaginable diversity.  Things that once seemed like creatures that rarely inundated hosts and caused problems for people and other animals started to seem much more ubiquitous and subsequently much more vital to a healthy ecosystem.  I started to learn that parasitism was an extremely common and successful way of life for a plethora of invertebrate creatures.  They lived in things, on things, and around things.  They seemed to be interwoven into every aspect of biology...genetics, immunology, ecology, you name it!  Being a parasitologist was more than understanding a single phylum or class of was about understanding biological principles in a broad sense as well as understanding specifics of whatever creature you specialized in working with. 

These creatures really do have a hand in every biological jar. One of the most fascinating aspects of parasitology is the insane intricacy of parasite evolution.  Parasites have been the driving force of adaptation in more species than I can count.  They have been the culprits behind many of the evolutionary arms races amongst a wide variety of host species.  As they become better at evading the immune systems of their hosts, hosts develop better means for detecting the presence of parasites and back and forth the battle rages.  They affect more than animal immune systems.  In many instances they affect animal morphologies, physiological processes, and even host behaviors.  Many parasites are master of host manipulation and behavioral modification.  They have developed an arsenal of clever ways to transfer themselves from one host to another. I think Carl Zimmer put it best in Parasite Rex when he said, "When it comes to the tapestry of life, parasites are the hand on the loom." How elegantly beautiful is that?

With such fascinating life styles, I don't understand how any knowledgeable person could not be fascinated or at the very least intrigued by natures most "terrifying" creatures.  From snakes, to wasps, to spiders and parasites...nature has shown me that choosing to stay fearful and ignorant keep you from ever seeing some of the really interesting and amazing things she has to offer.  Things that most people fear in nature or know very little about are often some of her best works of art. Her underground gallery is rife with stories and images that would evoke the most profound emotions and senses of wonder if only more people would take the time to find the exhibitions.  This is why I'm so passionate about the "disgusting"...this is why I love spiders and parasites.  Call me a biological hipster (the only form of "hipster" that I wouldn't punch someone in the face for calling me) but having access to mother nature's underground gallery makes me feel privy to the exclusive works of art that we all, in reality, possess the potential to see for ourselves in we just take the time to look.

Sunday, May 5, 2013

Dermatobia hominis: The Human Skin Bot

D. hominis larva
For those of you who haven't already heard, I made a journey across the state yesterday to my home for the summer.  I'll be spending the next three months working at a biological field station owned by the university I am attending.  Yesterday while sitting in the dining hall, I saw an adorable little rabbit hopping around the cedar trees.  The first thing I thought about was how I scared my roommate last week with a video of a bot fly emerging from a recently killed rabbit.  (You can view this video yourself here.)  When I awoke this morning and began thinking about what to write for today's post, I realized I had never really talked about bot flies.  So here we are! There were lots and lots to chose from, but I decided we would take a human perspective and look exclusively at the human skin bot (Dermatobia hominis) for this post.

As you probably already know, flies are animals belonging in phylum Arthropoda under the class Insecta. All flies belong to the order Diptera, meaning "two-wing"; this is in reference to the fact that these insects have only one pair of wings as opposed to two pairs like most other insects.  The second pair of wings in most flies have been reduced to vestigial structures called "halteres".  These structures now function mostly as balancing organs and have a knob-like appearance.  This order houses about 120,000 species representing 140 families.  The family that contains bot flies is the family Oestridae.  This family is split into four subfamilies: Cuterebrinae (skin bot flies), Oestrinae (head maggots), Hypodermatinae (cattle grubs, ox warbles, and heel flies), and Gasterophilinae (stomach bots flies infecting horses and their relatives, elephants, and rhinos).  Our D. hominis is found in subfamily Cuterebrinae and is common from Southeast Mexico down through the South American continent, extending to Argentina and Chile. Though we call it the "human skin bot", it will actually develop beneath the skin of just about any warm-blooded animal...mammals or even birds.

Adult human skin bot fly
Life Cycle,
The life cycle of this fly is similar to other flies in that it involves the laying of an egg what will hatch into a larva, which will go on to form a pupa from which an adult fly will eventually emerge.  Unlike most flies that infect their hosts (a condition known as "myiasis" which we will discuss in a moment), this fly does not lay eggs directly onto their hosts' bodies.  Nope, these guys are much more devious. An adult female fly will catch another parasitic insect, like maybe a mosquito, and glue her eggs onto the insect's body with the opercula (little flaps that open to release the eggs' contents) of the eggs facing downward.  It is unknown how many different types of insect carries are used by D. hominis, but there are at least 48 different types of flies and on tick species that have been known to be carriers.  Once one of these carriers lands on warm skin, the opercula open releasing the larvae onto their new hosts.  The larvae then burrow into unbroken skin and make a home in the dermal layers of the skin, where they stay for about 6 weeks before burrowing out of the skin and falling into the soil where they form a pupa and undergo metamorphosis, emerging as adult flies ready to mate and restart the cycle.

Bot fly larva being removed from a leg
This is the clinical term for an infection of fly maggots.  This can occur either opportunistically, as is the case in facultative myiasis...a condition in which  a non-parasitic maggot accidentally winds up in a host, or it can occur as part of a parasitic fly's life cycle, which is the case with obligatory myiasis.  If one becomes infected with D. hominis, that is obligatory myiasis.  Myiasis can occur just about anywhere there is exposed skin for a carrier to land on.  In fact, I even ran across a case of penile myiasis...that's right, some poor schmuck got infected with a bot fly on his penis.  No matter the site, these types of infections cause painful lesions, but almost never results in secondary infections.  In fact, there have been reports that fly maggots actually secrete antibacterial substances that are alkaline in nature, making wounds unfavorable environments for bacterial growth!  How cool is that??!!!

Human skin bot fly larva

No matter how awesome it is that these guys make antibacterials from their spit, they are not fun to have burrowing into your dermis.  The best way to remove a bot fly larva from yourself is to suffocate the little guy and then pull him out by squeezing or using tweezers.  There are several ways to suffocate the larva.  One way is to put tape over the wound, but this is not recommended as it can actually rip the larva causing problems with total removal.  Another, less damaging way is to apply several coats of nail polish to the wound, but this can be problematic when removing the nail polish and is easily applied incorrectly due to the nature of skin.  The best, most effective way with the easiest cleanup is to apply a generous coating of petroleum jelly to the wound.  Which ever method you use, leave the applied substance on the wound for about a day or more, then you can remove the substance and subsequently remove the fly.  Some sources say that a venom extractor (found in snake-bite first aid kits) can be very effective at removing these larvae.

Moral of the Story
I think if you get a bot fly,
someone should buy you this shirt.
If you travel south for research or for funzies, be sure to take both insect repellent and petroleum jelly.  A snake-bite kit wouldn't be a bad idea either! Also keep in mind that though these things seem scary, they have tremendous potential in the field of medicine.  Perhaps if we could isolate some of these secretions, we could get new forms of antibacterial medicines or even substances that can be used to treat necrosis (dying tissue).  Heck, maybe someone already has figured out how to do either or both of those things! The point is if you do get a bot fly, remember that it is easily treated and that you aren't likely to get any weird secondary infections. Easy enough to deal's all mind over being freaked out by a parasite! :p