Vampyroteuthis infernalis, not because it sucks blood but "because they have the ability to ‘cape’ themselves up with their membrane, which is black underside, looking just like a vampire wearing a black cape!" More
Vampire squid have eight webbed arms, tipped with suckers and lined with fleshy spines (called cirri), and two retractable sensory filaments. When threatened, it inverts so that the cirri point outwards in a menacing fashion.
Example of bio-luminescence in Firefly squids. You can see the bottom of each squid that shine through the numerous Photospores like the starry sky. Like the firefly squids, this makes vampire squids to try and disguise themselves from predators. Vampire Squid Facts for Kids!