speaking of bad-ass arthropods, how about coconut crabs? they are the largest land-dwelling arthros (spiders, crawfish, etc are arthropods too), they weigh in at nearly 10lbs, and they are hilariously strange.
they are strong enough to break coconut shells–as their name suggests, their main food source is coconuts that have fallen off the tree.. their claws are sharp enough to cut off a human finger, and some people believe they killed amelia earhart (i could not make this shit up). . they are compulsive thieves, earning the nickname ‘robber crab’. basically, this crab would totally fuck you up.
these gigantic sea-bugs have evolved to live on land; they will drown if immersed in water for too long! coconut crabs have evolved a kind of gill-lung called a branchiostegal lung. all crabs have a sense of smell, but coco-crabs have scent organs that look more like the scent organs of insects, because the process of scent-detection is very different in air or underwater. c.crabs even wiggle their antennae (where their smellers are located) to smell, just like insects! kiiiind of cute.they can live up to sixty years, which seems unfair, because they are just giant bugs, and cats are way better but they only live for like fifteen years. WELL. that’s neither here nor there. but, let it be known that coconut crabs have amazing longevity, considering they don’t even have an internal skeleton. they start out life hiding in shells, like regular hermit crabs, but as they age their abdomens harden and become a true exoskeleton. this exoskeleton has to be moulted periodically, so the crab will dig a hole and hide out there while it’s vulnerable. some crabs eat moulted exoskeletons, which is kind of disgusting.
these crabs live all over the pacific & indian oceans: basically, everywhere there are coconut palms. they are fairly rare on islands where humans live, because their meat is supposedly delicious and an aphrodisac. although i am suspicious of both these claims. their rarity means there is a good likelihood you will not find them in your garbage can or stealing your stuff (what do they even steal that they are called ‘robber crabs’? your stash of coconuts, bananas, or rotten meat?). apparently, once a coconut crab pinches down, it pincers can only be deactivated by tickling its under-abdomen. JUST ANOTHER REASON TO AVOID A SHOWDOWN. who is going to have the presence of mind to tickle a crab mid-fight? yes, i know, it’s just a giant crab, humans eat these guys all the time, but they’re still somewhat terrifying!
to summarise: giant land-crab. habitual thief. potentially tasty. may outlive you. will totally fuck you up if given the chance.