Minoshiro are omnivores and mainly eat moss, lichen, fungus, various insects, and seeds. They are unaffected by poisons, separating it out of their food and storing it in their bodies. Because of this, minoshiro indirectly cleanse the soil. Their bodies also change colors depending on what they have recently eaten. This can be seen most obviously after a meal of mosses, when they turn bright green. This trait is also seen in sea slugs after eating sea anemones.
When a minoshiro is threatened, it will raise and rattle the quills on its back to intimidate predators. If the predator continues to advance, it will get hit with the quills, which are full of deadly venom. Something worth mentioning is that they never threaten humans in this way.
The minoshiro species includes giant minoshiro (a rare type with body length above two meters and covered in silver bristles), red minoshiro (with half-transparent red bodies), blue minoshiro (with blue-tipped feelers), rainbow minoshiro (covered in fine hairs similar to the powdery scales on a butterfly, and reflect light like jewel beetles), and various subspecies.
Their size and extremely unpleasant taste due to the poison in their bodies mean that minoshiro have almost no natural enemies. Their only predator is the tiger crab, which lurks under sandy beaches. Most cases of minoshiro being hunted by tiger crabs seem to occur around the time they make their annual migration to the beach in order to lay eggs.
Just to be completely clear, let me give a brief introduction about tiger crabs. They are ferocious carnivores descended from the swimming crab, with sharp, diamond-shaped shells forty-five to a hundred-twenty centimeters wide, colored to blend in with the sand, large pincers, three spikes on their heads, and serrated edges on the front of their shells. Their back legs are useful for swimming as well as for burrowing into the sand. Tiger crabs are capable of jumping up to two meters straight up out of the sand in order to catch their prey. They are common around Hasaki beach, but can also be found in meadows, forests, and mountains. They eat everything from frogs, lizards, snakes, and small mammals to sea birds, beached dolphins, whales and other sea creatures. Their heavy shells are nearly impenetrable, though when tiger crabs meet, they often fight to the death, and cannibalism is common. Despite their vicious nature, they are not considered a threat to humans.
It is said that minoshiro can autotomize parts of their bodies to escape from tiger crabs, as well as do other interesting things that I’ve not yet seen.