I think anyone who uses the internet on a regular basis can agree that, overall, YouTube is good stuff. It has its pitfalls for sure: bad karaoke, those stupid “jump scare” videos, and don’t even read the comments if any part of you actually likes people. That said, the democratization of video content allows us to see things that normally might not be accessible if our only outlets were TV and professional recordings. This is true in marine science. There are a ton of divers and fishermen out there taking video of what they see and posting it up on the internet, and from an ecological and scientific standpoint some of it is actually pretty interesting.
Basically, I wanted to procrastinate a little today, so I looked up videos of dogfish on YouTube.
Because a lot of these document interactions with divers and fishermen, they mostly concern feeding behavior. Plus feeding makes for great video, so there’s a disproportionate amount of that available. I’ll provide my “expert” commentary on what I think is going on in these videos.
This video taken in Norwegian waters shows a group of apparently unbaited dogfish partaking in pretty classic benthic foraging behavior. They prowl along the bottom, sweeping their noses back and forth through the algae to pick up the electrical fields produced by prey hidden within. At one point one of the dags actually grabs and gulps down something from the bottom. Interestingly, these little sharks seem to have no fear of the divers, swooping very close and even bumping into the divers. Whether these dogfish are acclimated to the presence of humans or are just genuinely fearless can’t really be told from this video.
All the description tells us for this video is that it’s testing “experimental fishing gear” in the Gulf of Maine. I don’t know what it’s attempting to accomplish since there seem to be no hooks present on this gear. What you do see quite well is the classic bite and shake behavior of feeding dogfish. I can’t tell what the line is made of, but whatever it is the first dogfish saws pretty neatly right through it. And that first dogfish appears to be some kind of vanguard; within seconds the bait is being mobbed by dozens of hungry little sharks. One of the theories of why predatory fish school is to take advantage of the senses of every member of the school in searching out prey. This might be what happened here: the first shark found the bait, and lead the rest of the pack in.
This might be one of the more intimidating dogfish videos I’ve seen. It’s maddeningly pixelated, which means we can’t see what those dogfish are mobbing. It could be bait, it could be a large fish, it could even be another dogfish in the school. Whatever it is, you get a real sense of how a school of dogfish could make short work of larger prey, which is something dogfish are blamed for quite often. Cool stuff.
Ah, YouTube, friend of science.