Killer Jellyfish

Jelly “fish” are not actually fish, and don’t have a brain - implying they cannot feel pitty. They can become either male or female, depending on their mood. The species Turritopsis dohrnii is immortal, because when it becomes old,  it simply transforms to the child form. The Irukandji jellyfish can sting humans to death.  So you better respect their authority!