Vampire Shark

Vampire sharks are a group of whale shark descendants that had diversified into many different shapes and sizes. Vampire sharks are unlike any shark in Earth's history, they evolved into true blood-sucking creatures. Their filter-feeding mouth of its whale shark ancestors has been modified into a suction cup-like tool with lots of small but sharp teeth to cut the skin of larger animals. They range from the size of a neon tetra to the size of a remora, depending on a species. But the most famous species, Dracula shark (Draculcarcharus vampirii), is the size of a common carp and is widely distributed across the Pacific ocean, where it can suck the blood off of baleen whale sharks, surviving baleen whale species (humpback whales, etc), shriggers, and among others.

Evolution
In the Late Holocene, man has vanished to extinction, thus ending the greatest mass extinction since the Late Permian era. Fortunately, whale sharks have survived due to humans who successfully protected whale sharks from the brink of extinction from human fishermen and poachers. Over time, the descendants of whale sharks start to diversify into many different shapes and sizes, with some evolving into parasitic blood-sucking vampire sharks to the gentle giant baleen whale sharks.