Sounds of butterflyfishes discovered


Threadfin butterflyfish, Hawaii

From LiveScience:

Talking Fish: Wide Variety of Sounds Discovered

By Charles Q. Choi
Special to LiveScience

posted: 27 December 2006

Increasingly scientists are discovering unusual mechanisms by which fish make and hear secret whispers, grunts and thumps to attract mates and ward off the enemy.

In just one bizarre instance, seahorses create clicks by tossing their heads. They snap the rear edge of their skulls against their star-shaped bony crests.

This and other discoveries made in recent years come as the focus on the sounds that fish make is growing beyond “really loud sounds that last a long time,” fish behaviorist Timothy Tricas at the University of Hawaii at Manoa told LiveScience.

“Seahorse clicks are brief, only about five to 20 milliseconds,” he said.

1,000 voices

There are more than 25,000 species of fish living today, more kinds than any other animal form with a backbone in the history of the planet. A lot of them appeared to have done well in school.

“We know so far that at least 1,000 fish species make sounds, with a huge diversity of means by which they generate and listen to sounds,” Tricas said. “There’s only a handful we know well so far.”

Tricas and his colleagues studied butterflyfishes, a family that includes 126 species with bright colors and striking patterns found on just about every coral reef in the world.

One group within the butterflyfish family, comprising more than 80 species, are the only fish known so far to couple their swim bladders, which are organs that improve hearing, with their body’s lateral lines, organs running down their sides that help detect motion in the surrounding water.

This might be akin to a person hearing sounds by wiring their ears together with the little hairs on his or her skin.

This setup in butterflyfish seemed like a possible new hearing system, “but no one had ever heard butterflyfish make a sound. We discovered they do,” Tricas said.

Using underwater cameras and sound recorders known as hydrophones on Hawaiian coral reefs, Tricas and his colleagues discovered butterflyfish emitted several types of sounds only 10 to 150 milliseconds long using tail slaps, fin flicks, fin spine extensions, grunts and jumps.

“If you’re up close to them with a hydrophone, you can hear the sounds, but the total power in a single sound is miniscule compared to the loud and long sounds the toadfish and [fish known as] midshipman can make, which can last for seconds or minutes and can be heard 10 to 20 feet away,” Tricas said.

Invasive tropical fish near Florida: here.

Humphead wrasse here.

Evolution of Teleost fishes: here.

1 thought on “Sounds of butterflyfishes discovered

  1. Sep 9, 12:29 AM EDT

    Hawaii researchers explore previously unseen deep coral reef areas, find juvenile fish nursery

    By AUDREY McAVOY

    HONOLULU (AP) — Scientists over the past month explored coral reefs in the remote Northwestern Hawaiian Islands that until recently were considered too deep for scuba divers to reach.

    Divers swam among previously unseen reefs as deep as 250 feet during a monthlong research trip to the islands by the National Oceanic and Atmospheric Administration vessel Hiialakai.

    They unexpectedly found nursery grounds for juvenile reef fish like parrotfish and butterflyfish. They also were able to collect specimens that may help them identify new species.

    “We were seeing reefs that no human has ever laid eyes on before,” Randall Kosaki, the research mission’s lead scientist and diver, said Tuesday. “We literally have better maps of the moon than we do of coral reefs in the Hawaiian archipelago.”

    Eighty-four percent of all coral under U.S. jurisdiction lies in Hawaii’s waters. About 15 percent are in state waters around the main Hawaiian islands. Another 69 percent are in the Northwestern Hawaiian Islands – a stretch of mostly uninhabited atolls that President George W. Bush made a marine national monument in 2006.

    Most scuba divers are able to go only about 100 feet underwater. Submersible vehicles are able to take humans deeper, but have been exploring at areas around 600 to 700 feet below the surface, Kosaki said.

    Between the area where scuba divers and submersible vehicles have traveled is a “twilight zone” that has long been unexplored, he said. It includes large swaths of coral reefs that can grow up to 400 feet underwater.

    “The coral reef habitat goes four times deeper than where we’ve been working prior to this,” Kosaki told reporters.

    Kosaki’s team, which returned to Oahu on Sunday, used new technology that allows divers to descend deeper than was possible just a few years ago. For example, the juvenile fish nursery was spotted among algae 170 feet deep.

    Brian Bowen, a research professor at the Hawaii Institute of Marine Biology, said scientists would need to study whether nurseries like these replenish fish populations in shallow reefs. Answering this question will help those managing coral reefs, he said.

    “If you’re dumping trash at 170 feet of water, you might be dumping it on the nursery grounds that keep your fishery going,” Bowen said.

    He predicted the Hiialakai’s research would lead to similar dive studies at coral reefs elsewhere in the Pacific and in the Caribbean.

    Kosaki said the monument’s reefs were very healthy. Almost no fishing takes place in the protected zone, allowing fish populations to thrive.

    The only human settlements are at a research outpost on Midway Atoll, meaning the reefs aren’t damaged by runoff from housing developments and paved riverbeds like the main Hawaiian islands.

    “At one time we had 100 sharks around us. It’s just something you don’t see here on Oahu or any of the inhabited islands,” Kosaki said.

    The team saw small areas of bleached coral caused by a spike in sea surface temperatures in August. An annual coral reef monitoring expedition, which is due to leave in two weeks, will monitor these areas further, Kosaki said.

    The marine monument is called the Papahanaumokuakea Marine National Monument.

    On the Net:

    Papahanaumokuakea Marine National Monument: http://papahanaumokuakea.gov/

    Like

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