Yesterday, a curious Santa Cruz resident spotted a number of Sea lions under the wharf who were caught sleeping above the waves. A few of these had numbers branded onto them, such as the one in the picture which had ‘7726’ on its side. This got the photographer wondering about why this was the case, so like many people these days, they asked the internet.

The image below was shared on Reddit, and the curious photographer got a response. This may seem like an obvious answer to those who work with wildlife but to others, it may not be as clear and it certainly wasn’t done out of fashion.

It turns out that this is done for scientific purposes, as one user explained it: “They receive a cold brand for research purposes! Information on freeze branding can be found here. They get branded as pups, it helps researchers to track and identify these fellers!”

In short, scientists often mark numeric identifiers on the animal’s back or flank, aiming to monitor the creature throughout its entire lifespan. Unlike tags, which may detach or wear away and are often less conspicuous, branding offers greater reliability. The sustained scrutiny of these branded creatures can yield a wealth of insights into their range, behaviors, and life histories, not only benefiting individual analysis but also enhancing our understanding of the entire species.