Sarcastic fringehead: The angry little fish that engages in mouth-to-mouth combat

Name: Sarcastic fringehead (Neoclinus blanchardi)

Where it lives: From San Francisco, to Baja California, Mexico

What it eats: Small prey such as fish, crustaceans, and squid eggs

Why it's awesome: Sarcastic fringeheads are best known for their silly name, extreme aggression and unconventional fighting style — essentially, angrily yawning at each other.

Usually found on rocky reefs or sandy seabeds between around 9 and 240 feet (3 to 73 meters) below the water's surface, these solitary fish make their home inside shells, clam burrows, rock crevices, "or even in empty cans and bottles if there is pollution," according to a 2014 AAAS article. 

Despite being small — usually around 3 to 8 inches (7.5 to 20 centimeters) long, although they can grow to 12 inches (30 cm)  — they can be extremely aggressive and attack almost anything that strays too close, including divers, according to the Aquarium of the Pacific in California.

If a female chooses a male to be her mate, she lays her eggs in his den for him to fertilize. He's then responsible for protecting the eggs until the young hatch.