Chapter 1: Understanding Barnacle Life

Typically, we envision animals as beings that exhibit movement. Unlike plants, which are stationary, animals are generally seen as dynamic. However, this perception has exceptions. There are sessile creatures, such as mussels, corals, and barnacles, that remain fixed in one location. But what if these organisms have the ability to move, albeit at a pace too slow for us to notice?

Barnacles are fascinating, unique marine organisms. Once their larvae find a suitable surface to inhabit, they settle and grow into adults without relocating. They attach themselves quite firmly, making it difficult to remove them without special tools. At first glance, it seems improbable that they could ever move, even slightly.

However, barnacles do possess the ability to relocate, and they engage in this behavior regularly. Research has revealed that barnacles on the backs of turtles shift positions over time. Scientists observed this through photographs, noting that these barnacles migrated at rates between 0.27 and 1.4 mm daily, often leaving behind traces of "cement."

In light of these findings, a collaborative effort among scientists worldwide examined both captive and wild turtles. A study published in October 2021 detailed various experiments conducted on barnacles residing on turtles as well as in laboratory settings. They found that barnacle movement seemed to correlate with water currents. The researchers proposed that barnacles shift locations to enhance feeding opportunities from passing plankton. Notably, this movement was found to be independent of the barnacles' reproductive cycles, suggesting that it was not influenced by neighboring barnacles on the same turtle.

It stands to reason that barnacles would have evolved this ability to optimize their feeding in areas with stronger water flow, despite their slow pace. Otherwise, their chances of settling in a beneficial position would be purely coincidental. In fact, the likelihood of a barnacle attaching itself in a high-flow area may be diminished due to the challenges of securing itself there.

So, let's add barnacles to our list of mobile creatures! If you want to make a humorous comment about the slow delivery times of the US Postal Service, perhaps we should refer to it as "barnacle mail" instead of the usual "snail mail."

Fun fact: Barnacles hold the record for having the longest penis relative to their body size among all animals!

Chapter 2: Insights from Marine Research