Here's why:
* Vocal cords are for making sounds. Many animals communicate in other ways, like using scent markings, body language, or visual signals.
* Different animal groups have different vocalization systems. For example, insects produce sound by rubbing body parts together (stridulation), and some fish use their swim bladders to make sounds.
* Even within a species, there can be variation in vocalization. For example, some bird species use their syrinx (a voice box different from mammals) to make complex songs, while others have a simpler vocalization.
Here are some examples of animals that don't have vocal cords:
* Fish: Most fish communicate through vibrations and other non-vocal methods.
* Insects: Insects use stridulation, rubbing body parts together, to make sound.
* Reptiles: Some reptiles, like snakes, are completely silent. Others make hissing sounds using their lungs.
* Amphibians: Frogs and toads use their vocal sacs to make sounds, but these aren't technically vocal cords.
So, while many animals have vocal cords, it's not a universal feature across all species.