The giant alpha rayzor, which comes into existence when hundreds of rayzors battle to become alpha and one wins, these triggers a mutation in them and lets them grow into alphas, when this happens, the alpha mutation gene is destroyed in all other rayzors of that generation, therefore every generation of Rayzors can only have one alpha.

The alphas usually stay in the ocean as prey is bigger and they have more room to swim, but will enter the water bubble from time to time, just to stir shit up and terrify the other creatures that live there.

As size comparison, you can see the silhouettes of the normal sized Rayzors in the image.

Rayzors & Art are mine