why are there a huge amount of different insect varieties, like in ants, but only a small amount of different varieties in animals such as crocodiles?

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why are there a huge amount of different insect varieties, like in ants, but only a small amount of different varieties in animals such as crocodiles?

In: Biology

Tiny changes in those small animals allow them to fulfill different niches and avoid competition. A tiny change in a crocodiles morphology wouldn’t do as much the separate it from the other croc species.

Ex. A slight change in the size of a birds beak (I know I changed examples but still) will change its primary food source. A small change in a crocs mouth.. will still make it be a top predator.

Because there are different levels of taxonomic ranks in biology – domain, kingdom, phylum, class, order, family, genus and finally species. There are lots of insects and in the same time there are lots of reptiles. Crocodiles are just a part of Reptilia class. Crocodiles have roughly the same variety as mosquitoes, comparing a family to a class is wrong in the first place.

I think a more relevant answer:

There actually used to be hundreds if not thousands of crocodilans (species) in the past and todays crocs/alligator are just the last survivors of an ancient lineage that was just outcompeted by other more evolved competition. They survived by being a niche animal that survives by filling a very very specific role (passive ambush predator in shallow water) that they fit very well. Outside of this role they are easily out-competed by other animals more evolved, this is why even if a larger variation of crocodile evolved it would die out because say wolves or lions would just be better at the role of land hunter.

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Many insects like ants however are generalists that dominate in the insect world, because of this when they evolve into new variations those variations are able to compete with other animals already in that field. Another good example is cats and dogs, there used to be a lot of other large predators like Terror birds, but eventually these two species alone came to dominate the field worldwide (bears being the only real exception) and from their gradually evolve new variations like small fox’s and giant tigers etc.

I think its about the size of animals, there aren’t as many possible niches for large animals like a tree browser like a giraffe, also bugs can be specialized for a very small area like a specific tree

I read somewhere that beetles have an unusually wide distribution, and a variation in species that is quote numerous…

There’s lots of great answers here. I’d also like to add that short life cycles and large quantities off offspring offer a large pool for desirable mutations coupled with more opportunities to perpetuate those mutations.