Fin Nippers

For a short period after the Time of Hunger the herring predators enjoyed a brief golden age; still looking similar enough to their prey to be able to hide in the shoals. As generations passed and their dinner grew wise to their tactics they were swiftly repelled. Now free from the constraints of blending in, fin nippers are rapidly speciating into a variety of forms.

Fin nippers are now noticeably larger than their common herring ancestors, though the size difference is not yet enough to completely overpower their prey. Instead, fin nippers use hit-and-run attacks. They will slowly approach a shoal, and then with a burst of speed dash forward, biting wildly as the shoal scatters around them. This is usually enough to secure multiple mouthfuls of flesh and (as the name suggests) a tail fin or two. A particularly lucky strike may see a herring mortally wounded or crippled to the extent it can’t keep up with the shoal; these are soon dispatched by the nipper, who will literally eat it alive piece by piece.

To facilitate their switch from invertebrate to vertebrate prey, the jaws of fin nippers have undergone significant changes. Herring have oval shaped teeth on the roof of their mouth; in fin nippers these teeth have grown significantly more pointy and are migrating towards the front of the jaws. Bony protuberances on the bottom jaw act as teeth substitutes. Due to the positioning of the upper teeth a fin nipper must extend its jaws further forward in order to actually hit its prey with something sharp. This limitation currently prevents fin nippers from being able to take down healthy fish, but due to evolutionary pressure the shape and function of their teeth and jaws is undergoing rapid development- much to the misfortune of the herring it eats.

Despite no longer being shoalers fin nippers will often form hunting groups. Although completely without pack tactics these hunting groups do increase the success rate of attacks, as a panicked herring fleeing from one predator may swim directly into the bite range of another. This has caused two very different selection pressures on the fin nippers: increasing size means more than a mouthful of food, but cooperative behaviour ensures more success. In time these two tactics will result in very different evolutionary pathways.