Male Sperm Whales Emit Loudest Known Animal Signal, Reaching 43 Miles

Q: Could the loudest sound in the animal kingdom be a secret weapon for deep-sea dominance rather than just a mating call?

Possibly, but the evidence so far points more strongly to long-range social signaling than to a literal weapon. The newly measured “clang” or slow click is the loudest known animal communication sound, produced only by male sperm whales and potentially audible up to 70 kilometers away. Its low frequency, extreme power and regular 5- to 10-second rhythm fit well with functions such as attracting females, advertising body size, or warning off rival males. Researchers at Aarhus University have specifically suggested it may serve as an “honest advertisement” of a male’s size, because bigger males with larger nasal organs can produce deeper, more powerful sounds. That does make it a kind of dominance tool in a behavioral sense. In the deep sea, where vision is limited and sound carries far, a signal that says “a very large male is here” could shape access to mates and reduce direct fights. Playback experiments are planned to test whether males retreat, approach or answer back, and whether females respond differently. But there is no evidence that these male clangs are used as a physical weapon. The more weapon-like idea belongs to sperm whales’ even louder, highly focused echolocation clicks, which some scientists have long suspected might help stun squid at close range. That remains unproven in the wild. So the best reading of the current science is that the clang is likely a tool for social or sexual dominance, not a confirmed acoustic weapon for controlling the deep sea.

Q: How do these massive predators use bouncing ocean floor echoes as a metronome for the loudest calls on Earth?

Male sperm whales appear to use the seafloor like an acoustic stopwatch: they emit an extremely loud “clang,” then wait for the echo returning from the bottom before producing the next one. That would explain the strikingly regular 5- to 10-second gaps researchers measured between calls, without requiring the whales to “count” internally over long intervals. The idea comes from recordings analyzed by Simone Videsen, Peter Teglberg Madsen and colleagues from Aarhus University. Using hydrophones in the Seychelles and comparing those data with recordings from Sri Lanka, Norway and Scotland, they found the clangs were the loudest known communication sounds from any animal, with source levels above 200 dB re 1 µPa. In deep water, those signals may travel as far as 70 kilometers. The whales produce the calls by forcing pressurized air through structures known as phonic lips in their large nasal complex, creating a deep metallic sound distinct from the shorter clicks used for echolocation and social codas. Because males make these clangs alone, scientists suspect they may function in mating or male-male competition, possibly as an honest signal of size or condition. The echo-metronome idea remains a hypothesis, but it fits the rhythm of the calls and the whales’ reliance on sound in dark ocean depths. Researchers now want playback experiments to see how other sperm whales respond, which could clarify whether the clangs attract females, deter rivals, or do both.

2 articles · Updated · Yahoo! Voices · Aug 11

Hydrophone measurements off the Seychelles found male sperm whales' low-frequency clangs are the loudest known communication signal in any animal, potentially carrying about 43 miles.
Recordings from Sri Lanka, Norway and Scotland showed the whales space each clang 5 to 10 seconds apart, a much slower rhythm than social clicks or hunting echolocation.
Researchers think the males may keep that timing by using echoes from the seafloor, while producing the metallic sounds with pressurized air through phonic lips in their huge noses.
The study still cannot explain the clangs' purpose, though scientists suggest they may attract mates or deter rival males and plan playback tests to see how nearby whales respond.