Apparently, some species of sharks have the ability to bark like dogs when threatened. Granted, the species that have been witnessed to bark—the swellshark and draughtsboard shark—aren't the most intimidating on their own.

What shark barks like a dog?

Like other Cephaloscyllium species, the draughtsboard shark has the ability to inflate its body dramatically in response to a predator; this defense mechanism may be behind reports of this species barking like a large dog.

Does a dog's bark mean anything?

Dogs don't just bark when they are excited, although it can seem that way when they are trying to get your attention. They bark when they are frightened, lonely, surprised, irritated, and more. That means there are different barks for different moods, as well.