Common lionfish (Stephen Masters / CC BY)
Lionfish (Pterois sp.) are members of the scorpionfish family. They are characterized by elongated, feather-like fin rays. Their coloring of red, white, or black bands warns potential predators against their venomous spines. Most species range from 12 centimeters (5 inches, pygmy lionfish) to 45 centimeters (18 inches, longspine lionfish) in length. Lionfish are infamous for their venomousness. A sting causes extreme pain and is sometimes fatal to humans. If provoked, the lionfish swims with erected dorsal spines toward its enemy.