Chloe Abbasi
Out of all marine life, barnacles are one of the most overlooked species found in the ocean. Mostly because they are seen as an annoyance, sticking to everything and anything from ships and docks to whales and other sea creatures (Figure 1). However, barnacles’ super strong adhesion is exactly what makes them so unique, even if their sticking to everything can be a nuisance.
As seen in Figure 2, barnacles have a part of their life cycle where they choose where to settle down, called the cyprid stage (Fertyl & Newman 2018). During the cyprid stage, barnacle larvae can walk around while finding a place to settle. Once they find a place that’s just right, the cyprid larvae secretes a reversible adhesive called a footprint (Liang et al. 2019). The footprint allows for changes in location before settling down for good. Next, the larvae secretes another adhesive, this time permanent, called cement. Lastly, the barnacle secretes a second cement to maintain firm attachment (Fertl & Newman 2018). All of these layers combine to make the strongest biological glue that’s ever been seen!
Barnacle adhesive strength is something that has been of interest to scientists for a while now. The cements ability to stick to surfaces so strongly while also being able to work underwater is a feat that humans have not been able to replicate. Thus, the search for the components of this adhesive began. Scientists have been able to find traces of proteins and lipids in the glue from barnacles, and more recent research has shown a non-protein layer that is lipidaceous and is enclosed in phospho proteinaceous bulk glue (Liang et al. 2019). Since the lipid and protein phases are stored separately in alpha and beta cells, the amount of coordination needed to make this adhesive is astounding (Lian et al. 2019). As of now, no protein from the cyprid cement has been isolated yet, but proteins that adult barnacles use for adhesive were also found in cyprid cement glands, showing a possible connection. If, or when, scientists are able to isolate these proteins, they’ll also be able to study them more in-depth and determine how exactly they work for adhesion. Regardless, their super strength glue is a characteristic that is truly marvelous.
While barnacles also like to use their stickiness to attach to marine mammals, these mammals don’t particularly enjoy their company. Larger animals like whales don’t tend to notice the growth of multiple barnacles, however smaller mammals, such as dolphins, have been found to be hindered by barnacle attachment due to a decrease in mobility (Fertl & Newman 2018). And of course, humans don’t enjoy the presence of barnacles on the bottoms of ships, which decreases the speed of the vessel. Overall, barnacles are rather disliked by humans and marine life because of their stubborn settlement, but the cement they secrete is truly one of a kind, and one worth researching.
References
Fertl, D., & Newman, W. A. (2018). Barnacles. Encyclopedia of Marine Mammals, 2008, 75–78. https://doi.org/10.1016/b978-0-12-804327-1.00060-1
Liang, C., Strickland, J., Ye, Z., Wu, W., Hu, B., & Rittschof, D. (2019). Biochemistry of Barnacle Adhesion: An Updated Review. Frontiers in Marine Science, 6(September), 1–20. https://doi.org/10.3389/fmars.2019.00565
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