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Arugulus sure know how to get under a fish's skin, literally.
Fish will actually throw themselves out of the water to get an Aruglus off of their side.

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The first 1,000 people to click the link in the description can get a free trial of Skillshare’s Premium Membership. Do you ever wonder what it might take to make a fish mad?

Not just like a little irritated or cranky, but fully leaping-out-of-the-water mad? Like maybe you’ve done that thing you shouldn’t be doing where you tap your fingers impatiently at the glass of an aquarium just to get a bit of a rise out of its residents. But they just glide on by like you don’t even matter.

You’re just a creature on the other side of the glass, more provoked by a fish than it is by you. But let us suppose you wake up tomorrow, as Kafka might say, from uneasy dreams, transformed in your bed into a monstrous vermin. Instead of the soft, malleable casing of your skin, you are now armored with a rigid exoskeleton made of chitin that you will periodically shed and regrow.

Your body is now an oval, with four pairs of legs attached to the middle, thoracic region. And what does your head look like? It looks weird.

Almost a bit like a butt, right? Except that structure at one end of you is neither head nor butt. It is, for males, the testes.

And for the females, it is the spermathecae, a place to store sperm. This is your actual head. Much cuter, if you can call a head equipped with suction cups and a needle cute.

But it is a head, similar to your streamlined body, that is built for one purpose. Because you are a fish louse, and you are about to provoke a fish. Now despite what the name suggests, you are not actually a louse.

You aren’t even an insect. You are one of more than 100 freshwater crustacean species called Argulus. While you and your kind are found throughout the world, some of your relatives likely got their start long ago in Asia.

They spread around the world as the trade of carp and goldfish spread not only the fish but their closest friends as well. Well, perhaps friends is not the right word. Parasite.

That one that fits better. Of course, the name doesn’t matter to you. Nor does your historical background.

Why track some origin that’s ancient compared to your lifespan when you probably don’t even remember your own origins? The mucus-coated egg laid in a white mass. Perhaps the weather was warm, and you spent only a few days amongst the other eggs.

Or maybe it was colder, and you waited weeks. And then when you hatched, you had many siblings—anywhere from tens to hundreds of them. But you’ve gone your separate ways now, in search of your next meal, and your next home.

Two things that are, for you, the same thing. And if you find them, you have the chance to live to the ripe old age of 60 days. But if your search turns up empty, then survival becomes impossible.

And that means the situation is urgent, but you do have a bit of time. Several days, potentially even up to two weeks, to swim through the water and find the right fish. Fortunately, you are not particularly picky.

Sure, you have your preferences. Who doesn’t? But at the end of the day, a meal is a meal, and a fish is a fish.

Sometimes, if you can’t find a fish, you’ll even make do with a frog. To get there first, though, you have to swim, paddling with your legs, and catapulting yourself from predators using lobes that attach to your belly to launch yourself away. But when the opportunity—or fish—presents itself, the main appendages at work are the suction cups, or suckers, that you keep stuck to your target.

And should you need to move, the suckers on their own are movable stalks, meaning that you can direct them independently to scurry across your meal. Once you have suctioned yourself appropriately, it’s time to feed. Your head comes equipped with a retractable stylet, that thin tube poking out like a parasitic unicorn’s horn.

Through that stylet will travel whole blood cells, ready to feed you. This is a content moment for you. A fish louse needs only one fish in its whole lifetime to sustain itself.

And while this may not be the way everyone would choose to live their life, who can argue with being well-fed? The fish, however, takes notice. As you take up residence on its skin and start feeding on it, oh boy, does the fish take notice.

And it will try to shake you. It will scratch its flank up against whatever objects are around, whether that’s a plant or a stone. It will leap into the air.

It might even jump onto the concrete of a garden pond, risking predators and death as it tries to get you off its back and out of its skin. Perhaps it wouldn’t have made such a foolhardy decision under normal circumstances. But in the fish’s defense, you have managed to get just under its skin enough, poking away with your stylet and proboscis and possibly even secreting toxins and digestive enzymes that feed you and irritate the fish.

And no one is quite themselves when they’re irritated. But you? Well, you will just go on, unaware surely of the damage you have caused, of the response you have provoked.

Because after all, to you, it wasn’t damage. It wasn’t meant to provoke. It was just one creature in search of food, through whatever means were available to it.

Thank you for coming on this journey with us as we explore the unseen world that surrounds us. And we would like to also say thank you again to Skillshare for supporting this video. If you’re feeling like diving headfirst into some fish now, you should probably know how to prepare it properly because you are not actually a fish louse.

And Skillshare can help with that, with courses like “Simplifying Raw Fish”. Chef Ken Oringer will take you through a 40-minute culinary class where he breaks down the basics of preparing fish at home. You’ll learn what to look for when buying fish, essential knife skills, how to select ingredients, and finally, how to put your own creative twist on each dish.

Skillshare is an online learning community that offers membership with meaning. With so much to explore, real world projects to create, and the support of fellow-creatives, Skillshare empowers you to accomplish real growth. It’s curated specifically for learning, meaning there are no ads to distract you, and they’re always launching new premium classes, so you can stay focused and follow wherever your creativity takes you.

And if you’re one of the first 1,000 people to click the link in the description, you can get a free trial of Skillshare’s Premium Membership. The names you’re seeing on the screen right now. They are a bunch of fish louses, no doubt about that.

They all came on this journey with us because they love to look at the beautiful world of the micro. All of these wonderful organisms that we’re able to capture thanks to the hard work of our Master of Microscopes James and his really wonderful advanced equipment. If you want to see more from our Master of Microscopes, James Weiss, you can check out Jam and Germs on Instagram or also on TikTok.

And if you want to see more from us, there is always a subscribe button somewhere nearby.