[INTRO ♪].

When you picture the food chain, it probably goes a little something like this:. Plant gets eaten by bug;.Bug gets eaten by frog or some other small predator,. And frog gets eaten by a bird or whatever— something bigger. That’s just how things are done in nature, right? ... except it’s really, really not.

Natural selection can lead to some pretty weird situations. And sometimes, that means a spineless invertebrate—like a beetle— takes on a smarter, stronger, bony vertebrate, like a frog. Or a worm eats a fish, or a crab eats a bird … you get the idea.

Dragonfly larvae, or nymphs, are absolute terrors in the aquatic habitats they call home. They eat pretty much whatever they can catch, which includes things like tadpoles and fish. They usually hunt by ambush, sitting and waiting until the perfect snack comes close enough for them to grab with their sharp, powerful mouthparts.

But some are more active predators. In 2016, biologists observed three nymphs scaling underwater plants to line up with their targets and then leaping out of the water to grab onto full-grown frogs with their bitey bits. The nymphs—which were actually longer than the frogs— proceeded to eat the frogs alive while they tried desperately to escape. 15 to 20 minutes later, it was all over.

And the researchers found another 15 dead frogs at the bottom of the little lake, which all had cuts suggesting the nymphs had killed them, too. Luckily, they aren’t large enough to take out anything bigger than a frog— because if they were, they’d be on everyone’s nightmare list. Now, there’s no shortage of spider species that could make this list.

But when you think of spiders that eat vertebrates, you usually don’t think of jumping spiders. They’re the cute, charming spiders— you know, like those little peacock spiders with the colorful butt flaps ... they wave 'em around to woo females. But one species—the regal jumping spider—isn’t afraid of a few bones in its meals.

At about 2 centimeters long, they’re pretty small compared to most lizards and frogs. That does not keep the spiders from snacking on them, though. Like other carnivorous jumping spiders, they hunt by ... jumping on their prey.

To succeed at that, jumping spiders have amazing eyes that can accurately perceive depth and even see in color. Their eyesight is so good that they’re a favorite for vision researchers. They’re also relatively smart— they can learn to use different hunting strategies for different meals, for example, or even complete mazes.

But what’s most impressive is how bold regal jumping spiders are. They seem to have no concept of their size, and will eagerly take on prey much larger than themselves, including things like lizards and frogs. It probably helps that they’re armed with venom.

If you want to talk about frog-killers, though, beetles in the genus Epomis are the real experts. At least two Middle Eastern species of these fairly large, ground-dwelling beetles have evolved to prey upon amphibians both as adults and as larvae. The adults hunt frogs and salamanders pretty much how you’d expect a beetle to.

They’re not exclusive frog-eaters, but when the opportunity presents itself, they attack with precision, slicing at the animal’s lower back to paralyze it. Their hard, beetle-y exoskeletons make it tough for the frog to do any damage in return, even though they can be much larger than the beetles. But more impressively, they seem to have no issue with the potent bufotoxins in many poisonous frogs and toads.

Still, it’s the larvae that should get credit for being master frog hunters— they have to be, since their diet is exclusively amphibians that are much larger than they are. To snag their meals, they can wiggle their antennae and mouthparts as a lure. When a hungry frog tries to nab a larva with its tongue, the beetle leaps into action, biting down on whatever part of the frog it can reach—usually its face.

From there, they just start eating, and for whatever reason, the frogs can’t get them off. When scientists set up 382 larva/frog battles in the lab, the frogs never succeeded in consuming the larvae. They got them into their mouths seven times, but they soon spit them back out, and then somehow, unharmed larvae still killed and ate the frogs afterwards.

And eventually, they picked the bones clean. This is an example of role reversal, where the predator becomes the prey, and it likely started out as a defensive move on the beetles’ part. They developed a way to dodge the frogs’ lightning-fast tongue lash, and once that had happened, well, what else are you going to do with that juicy frog that’s right there in front of you?

It would probably be more accurate to call the more than 2,000 species of praying mantises preying mantises— like, with an E, because they are absolutely brutal predators. They’re gangly bugs with weird, triangular heads and big eyes, and they usually blend in well with their surroundings. So they just hunker down and sit unbelievably still until some unfortunate creature with the right size and shape happens to venture a little too close.

Their spiky appendages might seem thin or breakable but they’re tougher than they look, and they’re great for grabbing and subduing all sorts of prey … including birds. When ornithologists went back through public and scientific records in 2017, they found 147 cases of mantises attacking small birds like hummingbirds. In most, they succeeded in killing and eating the bird, and in two-thirds of cases, the bugs seemed to be going for the animal’s brains.

That may be because brains are super nutritious for them, or because brain damage quickly stops the birds from trying to fly away. Though it’s possible the bird’s heads were just the easiest part to grab onto. Mantises have been seen chomping on amphibians, reptiles, and even small mammals— anything they can grab and hold onto with their spiked legs long enough to start gnawing at flesh with their sharp mouthparts.

That generally means things the same size or smaller than they are, though some can grow as long as 10 centimeters or so. Can you imagine what these things would eat if they had, like, a super paralytic venom or something, too? Let's just all be happy that insects are small.

The beautifully iridescent, segmented bobbit worms aren’t easy to spot because they live in burrows in the seafloor. But, that’s probably for the best because as pretty as their rainbow bodies are, their faces are terrifying. And they’re even scarier when you know what they do with them.

Each worm is armed with five antennae it can use to sense when a fish is lurking within striking distance. When a fish swims over the wrong patch of sand, the worm lunges up from its burrow, grabs on with its strong, sharp pincers, and drags its hapless meal down. Exactly what happens to the fish in the burrow is somewhat of a mystery, but one thing's for sure: they don't come out.

They’re basically real-life, marine versions of the graboids from Tremors. And these worms eat all sorts of fish, seemingly undeterred by usual defensive strategies like venomous spines or skin toxins. The only limit on their catch seems to be size— the worms can be 3 meters long, but their throats don’t get much bigger than a few centimeters across.

Still, they do a good job of consuming fish that are much thicker than that. Fire ants, meanwhile, have a more collaborative attack strategy. They get their name from their painful venom, which burns like the sun.

Trust me, I know. While one fire ant sting isn’t a huge deal, hundreds or thousands can be debilitating— and even lethal, if you’re a small animal. And since colonies can contain of hundreds of thousands of ants, where there’s one, there are usually many more.

Studies on cottontail rabbits in Alabama found that up to three-quarters of newborns were killed by fire ants, for example. They’re also known to raid lizard, alligator, and turtle nests, where they can kill 70% of the young reptiles at a time. And when there are a lot of ants in an area, entire generations of nesting birds can be wiped out.

The ants aren’t fast, which is why the animals they kill tend to be slow or helpless, like baby bunnies or fledgling birds. All this wouldn’t so bad if the ants were native to these areas, and therefore just doing their part as predators in the ecosystem. But the fire ants in places like the US and Australia don’t belong there— they originally came in from South America.

And the damage their attacks cause to these habitats makes them arguably one of the worst invasive species on the planet. Certainly one of the worst invasive species I’ve ever slid into while playing a game of soccer. Giant water bugs are pretty much exactly what they sound like: huge bugs that live in ponds, rivers, and streams.

They’re the largest true bugs, or Hemipterans, in the world— some species can be about as long as your hand, and that size allows them to take on some very big prey. They’re thought to dine on fish and frogs for the most part, but scientists have seen them snacking on turtles and snakes, too. There are even rumors they will attack and kill wading birds.

In one published report from 1907, an unlucky woodpecker was found with a large water bug wrapped around its neck, slurping blood and/or brains from its head. To take on such formidable prey, the bugs inject a potent venom with their needle-like rostrums while they hold onto their prey with their ginormous pincer-like arms. The tricky part is getting a hold of their meals in the first place.

They usually ambush their prey, but that means sitting around underwater and waiting for something to come by … and they can’t breathe water. So they have a built-in SCUBA system of sorts— they’re able to trap air under their wings and bring a bubble down with them. Some species can take this a step further and pump their wings in a special way so that the trapped air absorbs oxygen from the water.

And this lets them stay down for hours at a time—long enough for something tasty to show up. If you want to see one of these amazing critters for yourself, they’re actually not hard to find. They’re found on every continent except Antarctica, and they’re sometimes called “electric light bugs” because they’re attracted to lights at night.

But if you do see one, I’d recommend leaving it alone. They’re also called “toe biters,” for obvious reasons— and their bites are super painful. Last, but certainly not least, is a species that loves to defy expectations.

Not only are they invertebrates that can eat vertebrates, they’re huge land-dwelling crabs that can live for over half a century. I’m talking about coconut crabs, of course— the monstrous Indo-Pacific land crabs rumored to have eaten, and possibly killed, Amelia Earhart. Even calling them huge and monstrous does not really do them justice.

They can weigh up to 4 kilograms and measure a meter across, if you count their legs. And that name? It doesn’t come from them being the size of coconuts.

It comes from their ability to crack open coconuts. And if you can break open a coconut with your bare claws, breaking bird bones is nothing. That’s what one shocked biologist discovered in 2016.

No joke, he watched as a crab climbed a meter up into a tree to snap the wing of a sleeping adult red-footed booby. After the bird fell to the ground, the crab proceeded to snap its other wing, and then it and five other crabs spent the next few hours ripping the bird apart. Before that chilling observation, it was thought that these omnivorous crabs, like many other crabs, simply scavenged for the meat in their diets.

But, nope—they will hunt and kill for their food. So there you have it: from bird-killing crabs to frog-killing beetle larvae, the eight animals on this list prove that lacking a backbone does not make you spineless. Evolution can lead to predators in all shapes and sizes, even ones you’d least expect.

So let’s raise a glass to these fearsome inverts— and be glad that none of them are quite big enough to hunt us. Thanks for watching this episode of SciShow! If you like horrifying animals, you might like our list of seven animals with super weird teeth.

And as always, if you want to learn more about this weird, wild, and wonderful world, head over to YouTube.com/SciShow and subscribe! [OUTRO ♪].