3 hours ago
T049A4, or Templar, shows how tough killer whale skin needs to be. There is evidence of a number of scratches, likely from play with his/her family or hunting scars, from when prey get a bit snappy. The blotch on the fin tip is likely some sort of infection from bacteria which found their way into a lesion.
A recently published paper has done some illuminating work on killer whale skin. As with many animals, the skin makes up an ecosystem of its own, with communities of bacteria and other microbes (particularly algae in the marine environment) making a home there. This study used samples of killer whale skin from multiple populations - the Residents, Transients, and 3 of the Antarctic subpopulations - to look at the variation in the make up of these communities and what may cause it. Their work found that ecotypes had significantly different microbial communities living on their skin, even in populations that live in the same waters, such as the Residents and Transients. These differing communities were proposed to be formed through a number of diverging traits. I will use Residents and Transients as an example, but the ideas can be applied to the other studied subpopulations. Socially, Residents and Transients never come into contact. This means that microbes are never passed directly between them from skin contact with other individuals. However, the frequent contact between members of the close social groups within each ecotype reinforce the differing microbial communities. As well, different prey types will have different microbial communities on their bodies, so seals will pass on certain microbes to Transients while salmon contribute to the microbes on Residents. This interesting diversity is just one more difference to note between these populations which appear to naked eye nearly identical.
Source: Hooper et al. (2019) Host-derived population genomics data provides insights into bacterial and diatom composition of the Killer Whale Skin. Molecular Ecology 28, 484-502. at Victoria, British Columbia