By Harriet Harris
When it comes to honey bees, there is an alluring complexity to their structure and function as organisms that are often overlooked, instead, the focus lies on their crucial role in the ecosystem and global economy. However, this last week, I had the pleasure of attending an anatomy and dissection lecture by Dr. Dennis vanEngelsdorp and Dr. Anthony Nearman, where the complexity of these insects was brought to life. The marvels of how these insects achieve so much were explained thoroughly, with students dissecting honey bees for a truly hands-on experience by the end of class.
While many things amazed me during this lecture, one theme remained true: chitin and its role as a vital component that not only shapes the adaptability of honey bees but also plays a significant role in the evolutionary development of numerous organisms. And because I found this fascinating, I’d like to pass on what I learned: what chitin is, its evolutionary importance, and the role it plays for our dearly beloved honey bees.
Chitin is an aminopolysaccharide polymer, and the most abundant one occurring in nature at that.[1] In simple terms, chitin gives strength to the exoskeletons of various organisms like insects, fungi, and crustaceans.[1] Nearly 85% of animal species are arthropods, which means 85% of animal species are composed of chitin![2]
While many things amazed me during this lecture, one theme remained true: chitin and its role as a vital component that not only shapes the adaptability of honey bees but also plays a significant role in the evolutionary development of numerous organisms. And because I found this fascinating, I’d like to pass on what I learned: what chitin is, its evolutionary importance, and the role it plays for our dearly beloved honey bees.
Chitin is an aminopolysaccharide polymer, and the most abundant one occurring in nature at that.[1] In simple terms, chitin gives strength to the exoskeletons of various organisms like insects, fungi, and crustaceans.[1] Nearly 85% of animal species are arthropods, which means 85% of animal species are composed of chitin![2]
However, insects and eukaryotic organisms (organisms with cells that contain a nucleus) have not always roamed this earth. Around 520 to 535 million years ago, marine picocyanobacteria appeared in the ocean.[3] These picocyanobacteria acquired a trait that allowed them to utilize chitin, which gave them the ability to attach to chitin particles and create their mat-based existence in the water column.[3] These mats, also known as stromatolites, were able to photosynthesize, thus pumping waterways with oxygen.[4] Stromatolites expanded into the ocean, essentially creating underwater forests before trees ever existed.[3] Once oxygen was saturated in the waters it was then released into the air, allowing for life to flourish and evolve.[4] These mats are commonly regarded as the first form of life on earth.[4] What once began as planktonic life evolved into more complex living organisms and genomic streamlining, which resulted in the evolutionary boom responsible for life as we know it today.[3] So while many may think of insects and fungi as gross, we owe our existence to one of their major components – chitin.
When it comes to honey bees, chitin is responsible for a myriad of things. Chitin acts as a means of protection. The chitinous cuticle in both the exoskeleton’s outer layers, but also the inner layers of the honey bees, acts as a barrier to disease and deters consumption from pests like mites. This is why the Varroa mite is a major concern, as it has figured out a way to break the bees’ exoskeleton to feed, resulting in the feeding of the fat body, but also creating a passageway for secondary diseases.
A new and surprising fact for me was that when bees go through molting, they not only shed their outer layer of exoskeleton but must rip out their internal organs as well. I could not help but think of this one quote from Cynthia Occelli, “For a seed to achieve its greatest expression, it must come completely undone. The shell cracks, its insides come out and everything changes. To someone who doesn’t understand growth, it would look like complete destruction.” I think there is a lesson here for all of us, that growth can be painful and hard, and at times feel like you’re being ripped apart. But sometimes that is a temporary necessity. I find that once again, honey bees have bestowed a beautiful life lesson for me through simply being.
This is not where chitin’s usefulness ends though. I also learned that chitin waterproofs the bees’ bodies preventing dehydration, and also allows for flight. Honey bees use a method of flying called indirect flight, meaning their wings fuse with the use of hooks called the hamuli and the muscles attached to the thoracic wall contract horizontally and vertically to drive the wings in flight. These muscles are attached to chitin and rely on it for stability and strength. Bees are avid communicators. They dance and waggle to communicate with one another, but also use hairs, also known as setae, that cover their body to perceive the world around them. These setae are composed of you guessed it, chitin. The setae allow for proprioception, meaning a sense of position, movement, and force.
When it comes to honey bees, chitin is responsible for a myriad of things. Chitin acts as a means of protection. The chitinous cuticle in both the exoskeleton’s outer layers, but also the inner layers of the honey bees, acts as a barrier to disease and deters consumption from pests like mites. This is why the Varroa mite is a major concern, as it has figured out a way to break the bees’ exoskeleton to feed, resulting in the feeding of the fat body, but also creating a passageway for secondary diseases.
A new and surprising fact for me was that when bees go through molting, they not only shed their outer layer of exoskeleton but must rip out their internal organs as well. I could not help but think of this one quote from Cynthia Occelli, “For a seed to achieve its greatest expression, it must come completely undone. The shell cracks, its insides come out and everything changes. To someone who doesn’t understand growth, it would look like complete destruction.” I think there is a lesson here for all of us, that growth can be painful and hard, and at times feel like you’re being ripped apart. But sometimes that is a temporary necessity. I find that once again, honey bees have bestowed a beautiful life lesson for me through simply being.
This is not where chitin’s usefulness ends though. I also learned that chitin waterproofs the bees’ bodies preventing dehydration, and also allows for flight. Honey bees use a method of flying called indirect flight, meaning their wings fuse with the use of hooks called the hamuli and the muscles attached to the thoracic wall contract horizontally and vertically to drive the wings in flight. These muscles are attached to chitin and rely on it for stability and strength. Bees are avid communicators. They dance and waggle to communicate with one another, but also use hairs, also known as setae, that cover their body to perceive the world around them. These setae are composed of you guessed it, chitin. The setae allow for proprioception, meaning a sense of position, movement, and force.
The importance of chitin, as explored through the lens of honey bee anatomy and dissection under the guidance of Dr. vanEngelsdorp and Dr. Nearman, acts as a foundational evolutionary development. Its presence in bees not only provides structural integrity and protection but has assisted in the adaptation and evolution of these insects to thrive for millions of years. From the indispensable role it plays in survival and efficiency to the complex role it plays in communication; chitin is an indispensable component to the long-term survival of not only honey bees but all life on earth. All of this information was incredibly exciting for me as a beekeeper. So often I look at bees and focus on the future: how do we keep them healthy, what is our honey flow going to look like, will they make it through the winter? This constant barrage of questions, anxieties, and forward-thinking often leaves little room for thinking of the past. Through taking the time to understand the significance of chitin, both past and present, I gained a deeper insight into the processes that shaped life as we know it and am reminded of the delicate balance within all ecosystems that allows us and other organisms to continue to thrive and endure over time.
Works Cited
Works Cited
- Elieh-Ali-Komi, D., and M. R. Hamblin. 2016. Chitin and Chitosan: Production and Application of Versatile Biomedical Nanomaterials. International journal of advanced research 4:411–427.
- Phylum Arthropoda. (n.d.). Manoa Hawaii. https://manoa.hawaii.edu/exploringourfluidearth/biological/invertebrates/phylum-arthropoda
- Capovilla, G., R. Braakman, G. P. Fournier, T. Hackl, J. Schwartzman, X. Lu, A. Yelton, K. Longnecker, M. C. K. Soule, E. Thomas, G. Swarr, A. Mongera, J. G. Payette, K. G. Castro, J. R. Waldbauer, E. B. Kujawinski, O. X. Cordero, and S. W. Chisholm. 2023. Chitin utilization by marine picocyanobacteria and the evolution of a planktonic lifestyle. Proceedings of the National Academy of Sciences of the United States of America 120:e2213271120.
- Awramik, S. M. 1992. The oldest records of photosynthesis. Photosynthesis Research 33:75–89.
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