Toadfish Love Song A Research Hit

The love song of the lonely toadfish is giving scientists new insight on fighting human muscular diseases.

Blessed with a face that only a mother could love, some males of a type of toadfish called the plainfin midshipman work hard for a date, hiding under rocks in shallow waters and humming to attract egg-laying females.

The toadfish, which can be found in the North Pacific from California all the way to Alaska, makes the humming sound by vibrating a set of sonic muscles on its air bladder 6,000 times a minute for more than an hour at a stretch, an amazing combination of speed and endurance. The human heart, by contrast, beats about 60-80 times a minute.

That kind of muscular capability could lead to clues on fighting human muscle diseases, such as the weakening disorder nemaline myopathy, says Kuan Wang of the National Institute of Arthritis and Musculoskeletal and Skin Diseases. Nemaline myopathy, or NM, is a rare genetic neuromuscular disorder that can be fatal, especially in infants. Symptoms include delayed motor development, and weakness of arm, leg, trunk, face and throat muscles.

"It turns out, it's built for high-performance and wired for high speed," says Wang, chief of the NAIMS's Laboratory of Muscle Biology. His research was presented this week at a meeting in San Francisco of the American Society for Cell Biology and reported in the San Francisco Chronicle on Thursday.

Eventually, Wang hopes to learn enough about how the toadfish sonic muscle works to reverse engineer those qualities in human tissue. The idea is to understand how to coach human muscles to work faster and longer.

The love lives of toadfish have proved fruitful for other research.

Cornell University neurobiologist Andrew Bass has been studying how the fish make and hear noises, research that could eventually be used to help treat human auditory problems.

He discovered in the late 1980s that there are two types of male plainfin midshipman, which he labeled Type 1 and Type 2. Type 1 males make the noise, staking out "nests" in shallow water, waiting for a female to approach and then, after the female lays individual eggs on the rocks above, fertilizing each one in a process that can take 20 hours. The Type 1 male then watches over the eggs until they hatch.

Type 2, or "sneaker" males are, to be blunt, cads. They don't hum but hang around Type 1 males until a female approaches. During fertilization, sneaker males try to fan some of their sperm onto the eggs before taking off.

Having two types of toadfish is a plus for researchers, Wang points out, because it provides a built-in control group.

Not everyone is enthused about toadfish tunes; during the summer mating season when the bottom-feeding toadfish move into shallow waters their nocturnal calls have been known to annoy houseboat owners.

"Besides whales and dolphins, they are the vocal champions," says Bass, who has heard the song of the toadfish in Tomales Bay, a scenic spot north of San Francisco. "It was a really quiet night, one of those nights when the water was like glass. You could hear the sound on shore, that's how loud it was."

Bass is interested in studying the toadfish brain as a model of how sounds are made and heard. He's also looking at how hormones affect the development and maintenance of those brain structures in the context of sound production.

Toadfish are specialists in this area, making it easier to study, he says. "They're not pretty fish, but they're incredibly good at what they do."