These three crabs didn't make an appearance in new horizons. The crab and coconut crab are exclusive to Animal Forest e+, while the horsehair crab is only in new leaf and pocket camp. Since the crab and coconut crab were around before the diving mechanic was introduced, you'd catch them with a net! The coconut crab had to be shaken out of trees while the crab would wander around on the beach. I think it would have been nice for them to show up in more recent games to add more variety to the ways that crabs can be caught. The hermit crab and bagworms can be caught in a similar fashion, so what's the problem, Nintendo? What did you do with the crabs?
the missing crabs in question, from left to right: crab, coconut crab, horsehair crab.
the missing crabs in question, from left to right: crab, coconut crab, horsehair crab.