Mosquito
Mosquitoes of the genus "Toxorhynchites" never drink blood. This genus includes the largest extant mosquitoes, the larvae of which prey on the larvae of other mosquitoes. These mosquito eaters have been used in the past as mosquito control agents, with varying success.
Giant squid
The giant squid is the second-largest mollusc and one of the largest of all extant invertebrates. It is only exceeded by the colossal squid, "Mesonychoteuthis hamiltoni", which may have a mantle nearly twice as long. Several extinct cephalopods, such as the Cretaceous vampyromorphid "Tusoteuthis", the Cretaceous coleoid "Yezoteuthis", and the Ordovician nautiloid "Cameroceras" may have grown even larger.