Marvelous Maggot Sensila

Until a couple of months ago, I thought of maggots only as disgusting creatures. I would unexpectedly discover them somewhere odd, like a backpack where I had left an apple a couple of weeks ago. And ick! And then they’d turn into flies that are buzzing everywhere. It felt like a horror movie.

How Composting Maggots Changed My Mind

While that experience might ring true, once I learned about Composting Maggots, when I was in Bali earlier this year as part of the Digital Naturalism (Dinacon) conference, it was a whole different story.

The ones in question are the Black Soldier Fly, and unlike our American houseflies, these don’t land on our food and eat it. They are nourished mainly by what they ate as larvae (maggots). The composting maggots are far more efficient than earthworms, eating things that worms cannot digest, like fried chicken, and at a much faster rate. They are also more efficient than our houseflies and blowflies, which produce a much worse smell and can spread pathogens and disease. Humans are even producing black soldier fly larvae on an industrial scale as a viable food source for livestock, pets, and aquaculture. These composting maggots are genuinely amazing, and they have changed the way I view them forever. 

Data-Sonification of Composting Maggots

I even did a data-sonification of the composting maggots, which I featured on my new YouTube channel called BioSymphonic.

The Sensational Sensilia of Maggots

But now I want to get into the sensory organs of maggots, which are non-descriptively named Sensilia. They are tiny external sensory hairs and knobs found all over the body of maggots. 

 

Studies on fruit fly larvae found that the body contains numerous individual sensilia all over the body. The sensilia are often mechanosensory, looking at the physical movement of the hairs. Still, others possess chemical, thermal (heat), gustation (taste), and osmosensation — the ability to sense changes in osmotic pressure. 

 

However, the head of the fruit fly maggots (their pseudocephalon) contains four sense organs, each of which contains multiple different sensilla. This suggests cross-talk in detecting environmental cues because they contain different sensory inputs.

 

The individual sensilia then relay this information to the sense organs and nervous system, triggering the maggot or fly to react with the most appropriate physiological or behavioral response. This provides us with valuable insights into how the maggots perceive their surroundings and how they may respond. 

 

Maggot Sensila

Klann, M., Schacht, M. I., Benton, M. A., & Stollewerk, A. (2021). Distribution and morphology of selected external sensilla in T. castaneum larvae [Figure 1]. In Functional analysis of sense organ specification in the Tribolium castaneum larva reveals divergent mechanisms in insects. BMC Biology, 19:22. https://doi.org/10.1186/s12915-021-00948-y BioMed Central+1

Metamorphosis: The Maggot’s Second Act

Sensational sensilla are not the maggot’s only fascinating feature. Maggots first transform into pupae, a transformation between the immature and mature stage, which then transform into flies. Interestingly, these are technically the same organism — they have the exact same DNA — but they look completely different. Their bodies change, and their senses are completely different.

 

It’s the genetic expression of that DNA that changes, based on environmental factors. This is a stark reminder to us that we are not fixed beings, but rather a combination of our DNA and how it expresses itself in our particular environment. Like maggots, we are also not hard-coded creatures; we are flexible and we can be malleable.

 

It’s in that DNA that allows flies to have compound eyes, sophisticated odor sensors, and taste sensors. Even though they are tiny in comparison, they become more relatable in some sort of primitive way than a maggot can. I think about Jeff Goldblum slowly transforming into a fly. It appears in popular culture, like when Ric Ocasek’s head appears on a 1984 Cars video or lyrics to The Human Fly by the Cramps.

 

A Maggot’s World Is Not Our World

But maggots? No eyes, no feeling (at least as far as humans are concerned) of animal agency. They seem entirely other. There is also never just one maggot; always a squirming mass. This is actually because their writhing groupings help retain moisture and break down food more efficiently. Their modus operandi is to burrow into decaying matter, stay protected and moist in that squirming mass, and just eat away.

Perhaps this is where our feeling of disgust comes from; much like the bug-like insects of Starship Troopers, we have trouble relating to the physical form. They are tiny, moist, and squirmy. They feel alien and off-putting.

Yet, their simple senses bear examination. Imagine having such fine sensors for moving through matter, a rich world of decaying matter that surrounds your entire body. In that decay is your life, without true eyes or ears, just touch, taste, and the delicious pull of decay. Exposed air is secondary.  

We Don’t Know What We Can’t Sense

I think now of the fish joke, infamously told by the now deceased David Foster Wallace:

 

There are these two young fish swimming along, and they happen to meet an older fish swimming the other way, who nods at them and says, “Morning, boys. How’s the water?” And the two young fish swim on for a bit, and then eventually one of them looks over at the other and goes, “What the hell is water?”

 

The point is that we don’t know what we can’t sense. I’d like to be reincarnated as a maggot for just a day. My eyes and ears would wither away, and I could feel the rich world of decay through this sensilia. Just a day is all I’d want. I’d return with that experience of sensing moist decay as a delicious medium.