Università degli Studi di Pavia

Centro Interdisciplinare di Bioacustica e Ricerche Ambientali

The voices of marine mammals of the Mediterranean Sea

Physeter macrocephalus

The vocalizations of the sperm whale (Physeter macrocephalus) are made by very brief impulsive sounds, called clicks, organized in variable length sequences. These clicks generally reach 30-35 kHz in frequency with repetition rates of 2-3 clicks per second.
Generally the clicks are organized in sequences of variable length and they are produced by the animals during the dives, that last on average 30-50 minutes, when principal activity is the hunting and the recognition of the environment. Every sequence of clicks is followed by brief periods of silence or by sequences of clicks repeated at high rates called creak or runs (Mullins et to the., 1988) with a probable echolocation function.

At the end of regular sequences, short series of clicks with a stereotyped pattern can be emitted; these are calleded "codas" and may have a total duration of 0,5-5 seconds. The meaning of the codas is still uncertain: the studies conducted until now consider them as social communication signals because often when these signals are heard more than one animal are present. According to some authors the existence of codas with different patterns, perhaps characteristic of geographical zones, may indicate that sperm whales could have evolved a sort of regional identifier that animals of a same area would use as a recognition signal.
In the Mediterranean Sea, codas with the pattern / / / / (3+1) have been recorded in 99% of the cases; thus the 3+1 pattern can be considered typical of the Mediterranean Sea although it has been found in other areas.
Recently, a new sound type called “trumpet” has been identified and recorded. It is a weak signal that was recorded several times in the past, though only recently it has been definitively linked to sperm whales. Produced at the beginning of the immersion, only in a small percentage of animals, it has an unknown meaning, and it is even perhaps due to physiological processes that are activated at the beginning of a deep dive.

The isolated animals are generally silent when in surface and they vocalize according to recognizable patterns during the dives. In the case of social aggregations with males, females and calves, a large variety of click patterns are also emitted while animals are at the surface.
In the early years of underwater acoustics, the military sonars operators listened to these sounds and attributed them to a nonexistent carpenter fish; listening to a recording gotten with military sonobuoys seems really to listen to the noises of a carpentry. P_macrocephalus_3animals_Difarbuoy.wav (5.4MB) P_macrocephalus_3animals_Difarbuoy.mp3 (980kB)

Typical series of clicks emitted by a sperm whale while diving.
P_macrocephalus_clicks.wav (7.9MB) P_macrocephalus_clicks_short.wav (860kB)
P_macrocephalus_clicks.mp3 (1.4MB) P_macrocephalus_clicks_short.mp3 (160kB)

In some recordings it is possible to hear echoes from the seafloor (arrows) and from the coast. P_macrocephalus_clicks_echoes.wav (2MB) P_macrocephalus_clicks_echoes.mp3 (354kB)

Clicks emitted by two diving sperm whales.
P_macrocephalus_3animals.wav (8MB) P_macrocephalus_3animals_short.wav (1MB)
P_macrocephalus_3animals.mp3 (1.3MB) P_macrocephalus_3animals_short.mp3 (170kB)

Recording of a sperm whale creak. The emission rate of regular clicks (on left side) increases up to hundreds per second; the amplitude of the clicks decreases accordingly with the the increase in the repetiotion rate.
P_macrocephalus_creak.wav (2.1MB) P_macrocephalus_creak.mp3 (392kB)

Series of two “codas” with the typical Mediterranean pattern (/// / also reported as 3+1).
P_macrocephalus_codas.wav (860kB) P_macrocephalus_codas.mp3 (156kB)

A rare recording of a “trumpet” recorded by CIBRA in 1996. It is a tonal sound weaker than clicks that can be recorded at short range only. It is emitted just after the fluke-up, normally before the animals starts clicking. P_macrocephalus_trumpet.wav (350kB) P_macrocephalus_trumpet.mp3 (65kB)

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Created June 2005, updated August 2005