* Evolutionary Relationships: Crabs and limpets both belong to the phylum Mollusca. This means they share a common ancestor that lived millions of years ago. Humans, on the other hand, belong to the phylum Chordata, which diverged from the molluscan lineage much earlier.
* Shared Traits: While crabs and limpets look very different, they share some fundamental characteristics as mollusks. Both have soft bodies (though crabs have a hard exoskeleton), a muscular foot, and a mantle.
* Genetic Distance: The closer two species are on the evolutionary tree, the more similar their DNA will be. Since crabs and limpets are more closely related than either is to humans, their DNA will be more alike.
In summary: Even though crabs and limpets seem quite different, they share a closer evolutionary history than either does with humans. This means their DNA will be more similar.
