[貼圖] World's Loudest Animals

"Singing" Penis
Although not the loudest animal in terms of sheer decibels, the 0.07-inch (2-millimeter) water boatman species Micronecta scholtzi, pictured, does make the loudest sounds relative to its body size, scientists announced in June in the journal PLoS ONE.

Engineers  and evolutionary biologists in Scotland and France recorded the  boatman—which is roughly the size of a grain of rice—"singing" in a  tank. The aquatic insect's songs peaked at 105 decibels, roughly  equivalent to the volume of a pounding jackhammer within arm's reach.
The  chirps are loud enough that humans can hear the sounds while standing  at the edge of a boatman's pond. Fortunately for nature lovers, though,  nearly all the sound is lost when the noises cross from water to air.

Remarkably,  the boatman creates his songs by rubbing his penis against his belly,  in a process similar to how crickets chirp. Sound-producing genitalia  are relatively rare within the animal kingdom, but animals have evolved  hundreds of other ways to boost their hoots, howls, and snaps.

Heck of a Howl
The  howler monkey is the loudest land animal. Its calls, which some say are  actually more like growls, can be heard up to three miles (five  kilometers) away.

The  monkey's volume comes from its enlarged hyoid bone, a U-shaped bone in  the howler's throat that "isn't actually hooked to any of the [other]  bones, so it kind of just hangs there," said Dell Guglielmo, caretaker  for two howler monkeys at the National Zoo in Washington, D.C. The enlarged bone creates a throat sac in which the monkey's calls resonate before booming out.

The  monkeys have a variety of calls, likely for communicating location,  protecting territory, and guarding mates, but their vocabulary is yet  unknown to humans.

Loud as a Lawnmower
Only  the males of the common coqui frog sing, but their calls, recorded at  peaks of a hundred decibels from three feet (a meter) away, make them  the loudest known amphibians.

The  nocturnal frog's two-part "co-qui" call has a two-part meaning: Other  male frogs respond to the territorial "co" part of the call, while  females are attracted to the "qui."

In  the coqui's native habitat of Puerto Rico, the frogs are considered  part of the island's natural heritage. But in Hawaii, where the frogs  are quickly establishing themselves as an invasive species, residents  have spent many sleepless nights due to the noisy frogs, which, in  aggregate, are comparable to a lawnmower running all night, according to  the Hawaii Department of Agriculture.

Deep Singer
The blue whale is the loudest mammal of them all, with vocalizations that reach 188 decibels.
Blue  whales don't have songs as complex as those of humpback whales, but  their low-frequency "pulses"— some below the range of human hearing—have  been recorded more than 500 miles (805 kilometers) away.

A  few years ago researchers found that the whales had been lowering the  frequencies of their songs even more—by up to 30 percent since the 1960s  in some populations. One theory suggests that the whales no longer need  to sing at "high" pitches to be heard at a distance, because the  species, while still endangered, has rebounded since whale hunting was  banned in 1966.

Snap of Doom
The  snapping shrimp doesn't sing, chirp, wail, or hoot, but it just might  be responsible for the loudest noise produced by any living being.
These shrimp  stun prey by closing their specialized claws quickly enough to shoot  jets of water out at 62 miles (100 kilometers) an hour,  forming a low-pressure bubble of vapor behind the jet. When that bubble  collapses, it produces a hot, loud mini-explosion of 200 decibels,  which stuns or even kills the shrimp's dinner.
In colonies, the shrimps' noise is enough to hide submarines from sonar.

Cave Squawkers
You  wouldn't want to be around when oilbirds come home to roost—these cave  dwellers, the loudest known birds, can be deafening when gathered in  large groups.

Oilbirds  use echolocation to navigate in completely dark caves. But, unlike the  calls of most bats, the birdcalls are within the range of human hearing.  Each bird can produce squawks and clicks up to a hundred decibels at  close range, and colonies can contain thousands of birds.
The  oilbirds appear to use echolocation only within their cave homes and  not during their nocturnal foraging. This could be because their  sensitivity isn't very high: In one experiment, oilbirds flew straight  into plastic discs that were 4 inches (10 centimeters) wide, but they  were able to avoid 8-inch (20-centimeter) disks and larger.

Amplified Cricket
The mole cricket species Gryllotalpa vinae is the loudest of the insects. The critter uses its specialized front  legs to dig a megaphone-shaped burrow. Standing inside that dugout, a  cricket can chirp loudly enough that humans can hear it nearly 2,000  feet (600 meters) away.
Microphones  placed three feet (a meter) from a cricket's burrow entrance have  recorded peak sound levels of 92 decibels, or about the volume of a lawn  mower.
In fact, using the burrow, G. vinae is able to turn an astonishing 30 percent of its energy into sound.

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