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Are Toadfish and Frogfish the Same Creature?

7 September 1999

 

Toadfish and frogfish are members of two separate families and are not nearly as alike as are their respective amphibian namesakes.

 

For starters, these two unusual animals belong to different families of fish. The toadfish is part of the Family Batrachoididae while the frogfish is a member of the Antennariidae family. There are 69 species of toadfish and approximately 50 species of frogfish swimming in just about all of the world’s oceans.

 

Toadfish are small to medium size with large heads that are distinctly flattened. Their mouths are quite wide. In fact, if you are lucky enough to come upon a toadfish, you might think it is all mouth and head!

Its body is tapered so that it resembles a tadpole with fleshy fins. Off the coast of North Carolina, divers may sneak a peek at the oyster toadfish (Opsanus tau) perched in a piece of pipe or lying underneath other kinds of shipwreck debris.

Fish Song -- The toadfish gets its name from the sounds it makes when agitated, as this one is, or when guarding a nest of eggs.

 

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Masters of Disguise -- Like the toadfish, the frogfish blends in with its surroundings.

But a diver has to look hard to spot this master of disguise. Its camouflage allows the oyster toadfish to blend in perfectly with its surroundings, waiting for a meal of small fish or crustaceans to swim by its big mouth. This habit of not working hard for its living has earned it a reputation as a lazy fish by some scientists who have studied it.

 

Some researchers say the toadfish is a fish with an attitude – it’s been called belligerent, ill-tempered and aggressive. The toadfish’s name, and perhaps part of its reputation, comes from the grunting sounds it makes when it is caught. The male fish also makes the sound during spawning season -- possibly as a way to protect the nest of eggs it guards during the incubation period.

 

While it may sound like a truly disagreeable fish, Opsanus tau is actually very important to humans. The oyster toadfish has been used in studies of insulin and diabetes, drug metabolism, hearing, dizziness and motion sickness. In fact, two oyster toadfish were along for the ride when John Glenn made his famous return to space aboard the space shuttle last year. The fish were part of a continuing study to help scientists better understand the mechanisms that control our sense of balance.

 

There is one species of toadfish whose name sets it apart from its motley kin -- Sanopus splendidus, the splendid toadfish. Indeed, its striking, colorful appearance presents quite a contrast to the other members of the toadfish family. Found only on the reefs around Cozumel, Mexico, the splendid toadfish has a zebra-striped head and is accented with wide, yellow borders on almost all of its fins. Its ventral fin, located on the fish’s underside closest to its head, is entirely yellow.

 

Opsanus tau and the Atlantic midshipman (Porichthys plectrodon), which is a member of the toadfish family, are common to the North Carolina coast. The midshipman gets its name from the 600 or so button-like light organs that are arranged in rows along its body – like a midshipman’s coat!

 

The frogfish has a different shape than the toadfish and you might say it is a little more proactive in the way it hunts for food. The frogfish is round with a mouth that resembles a trapdoor. Above that trapdoor is a dorsal spine that, when wriggled over the mouth, acts as a fishing lure for small fish and crustaceans. The frogfish’s mouth can expand to 12 times its normal size in about eight milliseconds, enabling it to quickly gobble up prey mesmerized by the lure. Talk about fast food!

 

Frogfish species come in many different colors, including black and yellow. Like the toadfish, it is able to camouflage itself and blend in with its habitat. Some frogfish may look like sponges, complete with patterns in the skin that resemble the holes found in sponges. Others may look like clumps of seaweed or seaweed-covered rocks. In addition to its coloring, the frogfish’s gill openings are hidden behind its pectoral or side fins. That way, prey is not tipped off to its presence by outflowing water from the frogfish’s gills.

 

Three species of frogfish can be found off the North Carolina coast: the ocellated frogfish (Antennarius ocellatus); the singlespot frogfish (Antennarius radiosus); and the splitlure frogfish (Antennarius scaber). They range in size from three to 15 inches and can be found along the bottom in shallow waters.

 

Additional Resources

 

Marine Biological Laboratory, Woods Hole

Waikiki Aquarium: Marine Life Profile - Frogfish