Full Description

"Spectrographic analyses of these sounds indicate a behavioral change in feeding habit with age among the species studied. Juveniles and small adults, 127-254 mm in length, feed rather superficially by rasping algae from hard substrates producing a SCRAPE sound in the process. Individuals, 305 mm or greater in length, characteristically bite the hard substrates while feeding producing a CRUNCH which differs from the SCRAPE temporal and frequency structure."

"The CRUNCH is a feeding sound generated by the more leisurely bitting activities of parrotfishes 305-356 mm in length or larger. The SCRAPE is characteristically repeated in rhythmic sequence during the rasping type of feeding activity of parrot- fishes in the 127-254-mm size category. Acoustic properties important in dif- ferentiating the CRUNCH and SCRAPE in- clude the temporal spacing of repeated sounds, total frequency range spanned, the frequency range of maximum con- centration of acoustic energy (predomi- nant frequency range) and the number of component pulses making up the entire sound. Pulse, as used here, refers to the smallest unitary homogenous parcel of sound waves that can be defined through oscillographic or sound spectrum analysis. Table 1 is a compilation of the spectral analyses of field-recorded sounds pro- duced by several different species of feed- ing parrotfishes. All individuals repre- sented are within the 305-356-mm-and- above size range, and therefore feed by biting at hard substrates. Although the temporal and frequency characteristics of feeding sounds in Table 1 differ only slightly, there are several instances in which a loosely defined pat- tern seems to be present. For example, a predominant frequency level of 2000 Hz for the female Sparisoma viride and a 1000-4000 Hz level for the slightly larger male may represent a degree of frequency discrimination based on differences of sex or more likely size. In addition, a slightly higher frequency range of 0-8000 Hz is exhibited by Scarus coclestinus as com- pared with the 0-6000 Hz range of most other species, and a predominant fre- quency level of 2000-3000 Hz appears to be peculiar for Scarus guacamaia."

"The CRUNCH ts a long-duration soun with a variable number of pulses having a mean duration of 0.31 sec for the sounds analyzed. Most acoustical energy is contained in the range of 0-6000 Hz, with predominant frequencies below 4000 Hz. When this sound is repeated by one fish several times in succession, it is usually at irregular intervals but with a temporal spacing of generally not less than 1.0 sec. The larger CRUNCH-producing parrot- fishes leisurely take rather big deliberate bites from the algae-covered reef surface while hovering in the water just above. Each forward biting action is followed by a brief “recovery” maneuver of variable duration in which the fish draws back a short distance from the substrate before making another feeding lunge. The result, from one fish, is a series of CRUNCH sounds that occur irregularly spaced in time but are typically separated by no less than 1.0 sec. The SCRAPE is a high-frequency sound (up to 12,000 Hz) composed of from one to four pulses, characteristically repeated by one small fish in quick rhythmic se- quence. Individual SCRAPES in such a se- quence have a mean duration of 0.05 sec and are quite regularly spaced on the average at 0.5 sec from each preceding and following sound. The temporal spac- ing here again is directly related to the pattern of feeding behavior in the rhyth- mical rasping of algae-covered substrates. The methodical feeding manner of small parrotfishes in contrast with the variable and essentially irregular feeding ap- proaches of larger parrotfishes is a basic behavioral difference that accounts for differentiation between the two types of feeding sounds. The SCRAPE occasionally exhibits a predominant frequency range of 3000-5000 Hz. However, more com- monly the acoustic energy is spread rather uniformly over the total range of fre- quencies spanned. This property of the SCRAPE is readily identifiable in Figs. 6-9."

"To investigate the possibility that ob- served differences in feeding sounds were the result of variations in the physical properties of different coral substrates, a 457-mm_ Scarus guacamaia was isolated and monitored in a tank with several known species of coral—Diploria stri- gosa, Porites astreoides, Montastrea an- nularis, Colpophyllia natans and = Acro- pora palmata."

"It appears, therefore, that the species of coral itself is not a significant cause of frequency structure variations among par- rotfish feeding sounds. Whatever distinc- tions do exist are due to different species or sizes of feeding fishes or to other conditions that affect the fishes’ feeding behavior."

"Again, we find a gener- ally high level of acoustic activity associ- ated with parrotfish grazing throughout most of the afternoon hours and a total absence of such sound production during the early morning and late evening."

Observation Environment Quotes

"Hydro-Lab served as our base of opera- tions during a 7-day saturation dive (July 20 - July 27, 1971). Recordings of grazing sounds were made from within the habitat using a Sony TC 630 D tape deck and two 24 V DC amplifiers coupled with two Atlantic Research LC-10 hydrophones."

Sound Name Quotes

"Spectrographic analyses of these sounds indicate a behavioral change in feeding habit with age among the species studied. Juveniles and small adults, 127-254 mm in length, feed rather superficially by rasping algae from hard substrates producing a SCRAPE sound in the process. Individuals, 305 mm or greater in length, characteristically bite the hard substrates while feeding producing a CRUNCH which differs from the SCRAPE temporal and frequency structure."

Full Description

"Spectrographic analyses of these sounds indicate a behavioral change in feeding habit with age among the species studied. Juveniles and small adults, 127-254 mm in length, feed rather superficially by rasping algae from hard substrates producing a SCRAPE sound in the process. Individuals, 305 mm or greater in length, characteristically bite the hard substrates while feeding producing a CRUNCH which differs from the SCRAPE temporal and frequency structure."

"The CRUNCH is a feeding sound generated by the more leisurely bitting activities of parrotfishes 305-356 mm in length or larger. The SCRAPE is characteristically repeated in rhythmic sequence during the rasping type of feeding activity of parrot- fishes in the 127-254-mm size category. Acoustic properties important in dif- ferentiating the CRUNCH and SCRAPE in- clude the temporal spacing of repeated sounds, total frequency range spanned, the frequency range of maximum con- centration of acoustic energy (predomi- nant frequency range) and the number of component pulses making up the entire sound. Pulse, as used here, refers to the smallest unitary homogenous parcel of sound waves that can be defined through oscillographic or sound spectrum analysis. Table 1 is a compilation of the spectral analyses of field-recorded sounds pro- duced by several different species of feed- ing parrotfishes. All individuals repre- sented are within the 305-356-mm-and- above size range, and therefore feed by biting at hard substrates. Although the temporal and frequency characteristics of feeding sounds in Table 1 differ only slightly, there are several instances in which a loosely defined pat- tern seems to be present. For example, a predominant frequency level of 2000 Hz for the female Sparisoma viride and a 1000-4000 Hz level for the slightly larger male may represent a degree of frequency discrimination based on differences of sex or more likely size. In addition, a slightly higher frequency range of 0-8000 Hz is exhibited by Scarus coclestinus as com- pared with the 0-6000 Hz range of most other species, and a predominant fre- quency level of 2000-3000 Hz appears to be peculiar for Scarus guacamaia."

"The CRUNCH ts a long-duration soun with a variable number of pulses having a mean duration of 0.31 sec for the sounds analyzed. Most acoustical energy is contained in the range of 0-6000 Hz, with predominant frequencies below 4000 Hz. When this sound is repeated by one fish several times in succession, it is usually at irregular intervals but with a temporal spacing of generally not less than 1.0 sec. The larger CRUNCH-producing parrot- fishes leisurely take rather big deliberate bites from the algae-covered reef surface while hovering in the water just above. Each forward biting action is followed by a brief “recovery” maneuver of variable duration in which the fish draws back a short distance from the substrate before making another feeding lunge. The result, from one fish, is a series of CRUNCH sounds that occur irregularly spaced in time but are typically separated by no less than 1.0 sec. The SCRAPE is a high-frequency sound (up to 12,000 Hz) composed of from one to four pulses, characteristically repeated by one small fish in quick rhythmic se- quence. Individual SCRAPES in such a se- quence have a mean duration of 0.05 sec and are quite regularly spaced on the average at 0.5 sec from each preceding and following sound. The temporal spac- ing here again is directly related to the pattern of feeding behavior in the rhyth- mical rasping of algae-covered substrates. The methodical feeding manner of small parrotfishes in contrast with the variable and essentially irregular feeding ap- proaches of larger parrotfishes is a basic behavioral difference that accounts for differentiation between the two types of feeding sounds. The SCRAPE occasionally exhibits a predominant frequency range of 3000-5000 Hz. However, more com- monly the acoustic energy is spread rather uniformly over the total range of fre- quencies spanned. This property of the SCRAPE is readily identifiable in Figs. 6-9."

"To investigate the possibility that ob- served differences in feeding sounds were the result of variations in the physical properties of different coral substrates, a 457-mm_ Scarus guacamaia was isolated and monitored in a tank with several known species of coral—Diploria stri- gosa, Porites astreoides, Montastrea an- nularis, Colpophyllia natans and = Acro- pora palmata."

"It appears, therefore, that the species of coral itself is not a significant cause of frequency structure variations among par- rotfish feeding sounds. Whatever distinc- tions do exist are due to different species or sizes of feeding fishes or to other conditions that affect the fishes’ feeding behavior."

"Again, we find a gener- ally high level of acoustic activity associ- ated with parrotfish grazing throughout most of the afternoon hours and a total absence of such sound production during the early morning and late evening."

Observation Environment Quotes

"Hydro-Lab served as our base of opera- tions during a 7-day saturation dive (July 20 - July 27, 1971). Recordings of grazing sounds were made from within the habitat using a Sony TC 630 D tape deck and two 24 V DC amplifiers coupled with two Atlantic Research LC-10 hydrophones."

Sound Name Quotes

"Spectrographic analyses of these sounds indicate a behavioral change in feeding habit with age among the species studied. Juveniles and small adults, 127-254 mm in length, feed rather superficially by rasping algae from hard substrates producing a SCRAPE sound in the process. Individuals, 305 mm or greater in length, characteristically bite the hard substrates while feeding producing a CRUNCH which differs from the SCRAPE temporal and frequency structure."

Full Description

"Spectrographic analyses of these sounds indicate a behavioral change in feeding habit with age among the species studied. Juveniles and small adults, 127-254 mm in length, feed rather superficially by rasping algae from hard substrates producing a SCRAPE sound in the process. Individuals, 305 mm or greater in length, characteristically bite the hard substrates while feeding producing a CRUNCH which differs from the SCRAPE temporal and frequency structure."

"The CRUNCH is a feeding sound generated by the more leisurely bitting activities of parrotfishes 305-356 mm in length or larger. The SCRAPE is characteristically repeated in rhythmic sequence during the rasping type of feeding activity of parrot- fishes in the 127-254-mm size category. Acoustic properties important in dif- ferentiating the CRUNCH and SCRAPE in- clude the temporal spacing of repeated sounds, total frequency range spanned, the frequency range of maximum con- centration of acoustic energy (predomi- nant frequency range) and the number of component pulses making up the entire sound. Pulse, as used here, refers to the smallest unitary homogenous parcel of sound waves that can be defined through oscillographic or sound spectrum analysis. Table 1 is a compilation of the spectral analyses of field-recorded sounds pro- duced by several different species of feed- ing parrotfishes. All individuals repre- sented are within the 305-356-mm-and- above size range, and therefore feed by biting at hard substrates. Although the temporal and frequency characteristics of feeding sounds in Table 1 differ only slightly, there are several instances in which a loosely defined pat- tern seems to be present. For example, a predominant frequency level of 2000 Hz for the female Sparisoma viride and a 1000-4000 Hz level for the slightly larger male may represent a degree of frequency discrimination based on differences of sex or more likely size. In addition, a slightly higher frequency range of 0-8000 Hz is exhibited by Scarus coclestinus as com- pared with the 0-6000 Hz range of most other species, and a predominant fre- quency level of 2000-3000 Hz appears to be peculiar for Scarus guacamaia."

"The CRUNCH ts a long-duration soun with a variable number of pulses having a mean duration of 0.31 sec for the sounds analyzed. Most acoustical energy is contained in the range of 0-6000 Hz, with predominant frequencies below 4000 Hz. When this sound is repeated by one fish several times in succession, it is usually at irregular intervals but with a temporal spacing of generally not less than 1.0 sec. The larger CRUNCH-producing parrot- fishes leisurely take rather big deliberate bites from the algae-covered reef surface while hovering in the water just above. Each forward biting action is followed by a brief “recovery” maneuver of variable duration in which the fish draws back a short distance from the substrate before making another feeding lunge. The result, from one fish, is a series of CRUNCH sounds that occur irregularly spaced in time but are typically separated by no less than 1.0 sec. The SCRAPE is a high-frequency sound (up to 12,000 Hz) composed of from one to four pulses, characteristically repeated by one small fish in quick rhythmic se- quence. Individual SCRAPES in such a se- quence have a mean duration of 0.05 sec and are quite regularly spaced on the average at 0.5 sec from each preceding and following sound. The temporal spac- ing here again is directly related to the pattern of feeding behavior in the rhyth- mical rasping of algae-covered substrates. The methodical feeding manner of small parrotfishes in contrast with the variable and essentially irregular feeding ap- proaches of larger parrotfishes is a basic behavioral difference that accounts for differentiation between the two types of feeding sounds. The SCRAPE occasionally exhibits a predominant frequency range of 3000-5000 Hz. However, more com- monly the acoustic energy is spread rather uniformly over the total range of fre- quencies spanned. This property of the SCRAPE is readily identifiable in Figs. 6-9."

"To investigate the possibility that ob- served differences in feeding sounds were the result of variations in the physical properties of different coral substrates, a 457-mm_ Scarus guacamaia was isolated and monitored in a tank with several known species of coral—Diploria stri- gosa, Porites astreoides, Montastrea an- nularis, Colpophyllia natans and = Acro- pora palmata."

"It appears, therefore, that the species of coral itself is not a significant cause of frequency structure variations among par- rotfish feeding sounds. Whatever distinc- tions do exist are due to different species or sizes of feeding fishes or to other conditions that affect the fishes’ feeding behavior."

"Again, we find a gener- ally high level of acoustic activity associ- ated with parrotfish grazing throughout most of the afternoon hours and a total absence of such sound production during the early morning and late evening."

Observation Environment Quotes

"Hydro-Lab served as our base of opera- tions during a 7-day saturation dive (July 20 - July 27, 1971). Recordings of grazing sounds were made from within the habitat using a Sony TC 630 D tape deck and two 24 V DC amplifiers coupled with two Atlantic Research LC-10 hydrophones."

Sound Name Quotes

"Spectrographic analyses of these sounds indicate a behavioral change in feeding habit with age among the species studied. Juveniles and small adults, 127-254 mm in length, feed rather superficially by rasping algae from hard substrates producing a SCRAPE sound in the process. Individuals, 305 mm or greater in length, characteristically bite the hard substrates while feeding producing a CRUNCH which differs from the SCRAPE temporal and frequency structure."

Full Description

"Spectrographic analyses of these sounds indicate a behavioral change in feeding habit with age among the species studied. Juveniles and small adults, 127-254 mm in length, feed rather superficially by rasping algae from hard substrates producing a SCRAPE sound in the process. Individuals, 305 mm or greater in length, characteristically bite the hard substrates while feeding producing a CRUNCH which differs from the SCRAPE temporal and frequency structure."

"The CRUNCH is a feeding sound generated by the more leisurely bitting activities of parrotfishes 305-356 mm in length or larger. The SCRAPE is characteristically repeated in rhythmic sequence during the rasping type of feeding activity of parrot- fishes in the 127-254-mm size category. Acoustic properties important in dif- ferentiating the CRUNCH and SCRAPE in- clude the temporal spacing of repeated sounds, total frequency range spanned, the frequency range of maximum con- centration of acoustic energy (predomi- nant frequency range) and the number of component pulses making up the entire sound. Pulse, as used here, refers to the smallest unitary homogenous parcel of sound waves that can be defined through oscillographic or sound spectrum analysis. Table 1 is a compilation of the spectral analyses of field-recorded sounds pro- duced by several different species of feed- ing parrotfishes. All individuals repre- sented are within the 305-356-mm-and- above size range, and therefore feed by biting at hard substrates. Although the temporal and frequency characteristics of feeding sounds in Table 1 differ only slightly, there are several instances in which a loosely defined pat- tern seems to be present. For example, a predominant frequency level of 2000 Hz for the female Sparisoma viride and a 1000-4000 Hz level for the slightly larger male may represent a degree of frequency discrimination based on differences of sex or more likely size. In addition, a slightly higher frequency range of 0-8000 Hz is exhibited by Scarus coclestinus as com- pared with the 0-6000 Hz range of most other species, and a predominant fre- quency level of 2000-3000 Hz appears to be peculiar for Scarus guacamaia."

"The CRUNCH ts a long-duration soun with a variable number of pulses having a mean duration of 0.31 sec for the sounds analyzed. Most acoustical energy is contained in the range of 0-6000 Hz, with predominant frequencies below 4000 Hz. When this sound is repeated by one fish several times in succession, it is usually at irregular intervals but with a temporal spacing of generally not less than 1.0 sec. The larger CRUNCH-producing parrot- fishes leisurely take rather big deliberate bites from the algae-covered reef surface while hovering in the water just above. Each forward biting action is followed by a brief “recovery” maneuver of variable duration in which the fish draws back a short distance from the substrate before making another feeding lunge. The result, from one fish, is a series of CRUNCH sounds that occur irregularly spaced in time but are typically separated by no less than 1.0 sec. The SCRAPE is a high-frequency sound (up to 12,000 Hz) composed of from one to four pulses, characteristically repeated by one small fish in quick rhythmic se- quence. Individual SCRAPES in such a se- quence have a mean duration of 0.05 sec and are quite regularly spaced on the average at 0.5 sec from each preceding and following sound. The temporal spac- ing here again is directly related to the pattern of feeding behavior in the rhyth- mical rasping of algae-covered substrates. The methodical feeding manner of small parrotfishes in contrast with the variable and essentially irregular feeding ap- proaches of larger parrotfishes is a basic behavioral difference that accounts for differentiation between the two types of feeding sounds. The SCRAPE occasionally exhibits a predominant frequency range of 3000-5000 Hz. However, more com- monly the acoustic energy is spread rather uniformly over the total range of fre- quencies spanned. This property of the SCRAPE is readily identifiable in Figs. 6-9."

"To investigate the possibility that ob- served differences in feeding sounds were the result of variations in the physical properties of different coral substrates, a 457-mm_ Scarus guacamaia was isolated and monitored in a tank with several known species of coral—Diploria stri- gosa, Porites astreoides, Montastrea an- nularis, Colpophyllia natans and = Acro- pora palmata."

"It appears, therefore, that the species of coral itself is not a significant cause of frequency structure variations among par- rotfish feeding sounds. Whatever distinc- tions do exist are due to different species or sizes of feeding fishes or to other conditions that affect the fishes’ feeding behavior."

"Again, we find a gener- ally high level of acoustic activity associ- ated with parrotfish grazing throughout most of the afternoon hours and a total absence of such sound production during the early morning and late evening."

Observation Environment Quotes

"Hydro-Lab served as our base of opera- tions during a 7-day saturation dive (July 20 - July 27, 1971). Recordings of grazing sounds were made from within the habitat using a Sony TC 630 D tape deck and two 24 V DC amplifiers coupled with two Atlantic Research LC-10 hydrophones."

Sound Name Quotes

"Spectrographic analyses of these sounds indicate a behavioral change in feeding habit with age among the species studied. Juveniles and small adults, 127-254 mm in length, feed rather superficially by rasping algae from hard substrates producing a SCRAPE sound in the process. Individuals, 305 mm or greater in length, characteristically bite the hard substrates while feeding producing a CRUNCH which differs from the SCRAPE temporal and frequency structure."

Full Description

"Spectrographic analyses of these sounds indicate a behavioral change in feeding habit with age among the species studied. Juveniles and small adults, 127-254 mm in length, feed rather superficially by rasping algae from hard substrates producing a SCRAPE sound in the process. Individuals, 305 mm or greater in length, characteristically bite the hard substrates while feeding producing a CRUNCH which differs from the SCRAPE temporal and frequency structure."

"The CRUNCH is a feeding sound generated by the more leisurely bitting activities of parrotfishes 305-356 mm in length or larger. The SCRAPE is characteristically repeated in rhythmic sequence during the rasping type of feeding activity of parrot- fishes in the 127-254-mm size category. Acoustic properties important in dif- ferentiating the CRUNCH and SCRAPE in- clude the temporal spacing of repeated sounds, total frequency range spanned, the frequency range of maximum con- centration of acoustic energy (predomi- nant frequency range) and the number of component pulses making up the entire sound. Pulse, as used here, refers to the smallest unitary homogenous parcel of sound waves that can be defined through oscillographic or sound spectrum analysis. Table 1 is a compilation of the spectral analyses of field-recorded sounds pro- duced by several different species of feed- ing parrotfishes. All individuals repre- sented are within the 305-356-mm-and- above size range, and therefore feed by biting at hard substrates. Although the temporal and frequency characteristics of feeding sounds in Table 1 differ only slightly, there are several instances in which a loosely defined pat- tern seems to be present. For example, a predominant frequency level of 2000 Hz for the female Sparisoma viride and a 1000-4000 Hz level for the slightly larger male may represent a degree of frequency discrimination based on differences of sex or more likely size. In addition, a slightly higher frequency range of 0-8000 Hz is exhibited by Scarus coclestinus as com- pared with the 0-6000 Hz range of most other species, and a predominant fre- quency level of 2000-3000 Hz appears to be peculiar for Scarus guacamaia."

"The CRUNCH ts a long-duration soun with a variable number of pulses having a mean duration of 0.31 sec for the sounds analyzed. Most acoustical energy is contained in the range of 0-6000 Hz, with predominant frequencies below 4000 Hz. When this sound is repeated by one fish several times in succession, it is usually at irregular intervals but with a temporal spacing of generally not less than 1.0 sec. The larger CRUNCH-producing parrot- fishes leisurely take rather big deliberate bites from the algae-covered reef surface while hovering in the water just above. Each forward biting action is followed by a brief “recovery” maneuver of variable duration in which the fish draws back a short distance from the substrate before making another feeding lunge. The result, from one fish, is a series of CRUNCH sounds that occur irregularly spaced in time but are typically separated by no less than 1.0 sec. The SCRAPE is a high-frequency sound (up to 12,000 Hz) composed of from one to four pulses, characteristically repeated by one small fish in quick rhythmic se- quence. Individual SCRAPES in such a se- quence have a mean duration of 0.05 sec and are quite regularly spaced on the average at 0.5 sec from each preceding and following sound. The temporal spac- ing here again is directly related to the pattern of feeding behavior in the rhyth- mical rasping of algae-covered substrates. The methodical feeding manner of small parrotfishes in contrast with the variable and essentially irregular feeding ap- proaches of larger parrotfishes is a basic behavioral difference that accounts for differentiation between the two types of feeding sounds. The SCRAPE occasionally exhibits a predominant frequency range of 3000-5000 Hz. However, more com- monly the acoustic energy is spread rather uniformly over the total range of fre- quencies spanned. This property of the SCRAPE is readily identifiable in Figs. 6-9."

"To investigate the possibility that ob- served differences in feeding sounds were the result of variations in the physical properties of different coral substrates, a 457-mm_ Scarus guacamaia was isolated and monitored in a tank with several known species of coral—Diploria stri- gosa, Porites astreoides, Montastrea an- nularis, Colpophyllia natans and = Acro- pora palmata."

"It appears, therefore, that the species of coral itself is not a significant cause of frequency structure variations among par- rotfish feeding sounds. Whatever distinc- tions do exist are due to different species or sizes of feeding fishes or to other conditions that affect the fishes’ feeding behavior."

"Again, we find a gener- ally high level of acoustic activity associ- ated with parrotfish grazing throughout most of the afternoon hours and a total absence of such sound production during the early morning and late evening."

Observation Environment Quotes

"Hydro-Lab served as our base of opera- tions during a 7-day saturation dive (July 20 - July 27, 1971). Recordings of grazing sounds were made from within the habitat using a Sony TC 630 D tape deck and two 24 V DC amplifiers coupled with two Atlantic Research LC-10 hydrophones."

Sound Name Quotes

"Spectrographic analyses of these sounds indicate a behavioral change in feeding habit with age among the species studied. Juveniles and small adults, 127-254 mm in length, feed rather superficially by rasping algae from hard substrates producing a SCRAPE sound in the process. Individuals, 305 mm or greater in length, characteristically bite the hard substrates while feeding producing a CRUNCH which differs from the SCRAPE temporal and frequency structure."

Full Description

"Spectrographic analyses of these sounds indicate a behavioral change in feeding habit with age among the species studied. Juveniles and small adults, 127-254 mm in length, feed rather superficially by rasping algae from hard substrates producing a SCRAPE sound in the process. Individuals, 305 mm or greater in length, characteristically bite the hard substrates while feeding producing a CRUNCH which differs from the SCRAPE temporal and frequency structure."

"The CRUNCH is a feeding sound generated by the more leisurely bitting activities of parrotfishes 305-356 mm in length or larger. The SCRAPE is characteristically repeated in rhythmic sequence during the rasping type of feeding activity of parrot- fishes in the 127-254-mm size category. Acoustic properties important in dif- ferentiating the CRUNCH and SCRAPE in- clude the temporal spacing of repeated sounds, total frequency range spanned, the frequency range of maximum con- centration of acoustic energy (predomi- nant frequency range) and the number of component pulses making up the entire sound. Pulse, as used here, refers to the smallest unitary homogenous parcel of sound waves that can be defined through oscillographic or sound spectrum analysis. Table 1 is a compilation of the spectral analyses of field-recorded sounds pro- duced by several different species of feed- ing parrotfishes. All individuals repre- sented are within the 305-356-mm-and- above size range, and therefore feed by biting at hard substrates. Although the temporal and frequency characteristics of feeding sounds in Table 1 differ only slightly, there are several instances in which a loosely defined pat- tern seems to be present. For example, a predominant frequency level of 2000 Hz for the female Sparisoma viride and a 1000-4000 Hz level for the slightly larger male may represent a degree of frequency discrimination based on differences of sex or more likely size. In addition, a slightly higher frequency range of 0-8000 Hz is exhibited by Scarus coclestinus as com- pared with the 0-6000 Hz range of most other species, and a predominant fre- quency level of 2000-3000 Hz appears to be peculiar for Scarus guacamaia."

"The CRUNCH ts a long-duration soun with a variable number of pulses having a mean duration of 0.31 sec for the sounds analyzed. Most acoustical energy is contained in the range of 0-6000 Hz, with predominant frequencies below 4000 Hz. When this sound is repeated by one fish several times in succession, it is usually at irregular intervals but with a temporal spacing of generally not less than 1.0 sec. The larger CRUNCH-producing parrot- fishes leisurely take rather big deliberate bites from the algae-covered reef surface while hovering in the water just above. Each forward biting action is followed by a brief “recovery” maneuver of variable duration in which the fish draws back a short distance from the substrate before making another feeding lunge. The result, from one fish, is a series of CRUNCH sounds that occur irregularly spaced in time but are typically separated by no less than 1.0 sec. The SCRAPE is a high-frequency sound (up to 12,000 Hz) composed of from one to four pulses, characteristically repeated by one small fish in quick rhythmic se- quence. Individual SCRAPES in such a se- quence have a mean duration of 0.05 sec and are quite regularly spaced on the average at 0.5 sec from each preceding and following sound. The temporal spac- ing here again is directly related to the pattern of feeding behavior in the rhyth- mical rasping of algae-covered substrates. The methodical feeding manner of small parrotfishes in contrast with the variable and essentially irregular feeding ap- proaches of larger parrotfishes is a basic behavioral difference that accounts for differentiation between the two types of feeding sounds. The SCRAPE occasionally exhibits a predominant frequency range of 3000-5000 Hz. However, more com- monly the acoustic energy is spread rather uniformly over the total range of fre- quencies spanned. This property of the SCRAPE is readily identifiable in Figs. 6-9."

"To investigate the possibility that ob- served differences in feeding sounds were the result of variations in the physical properties of different coral substrates, a 457-mm_ Scarus guacamaia was isolated and monitored in a tank with several known species of coral—Diploria stri- gosa, Porites astreoides, Montastrea an- nularis, Colpophyllia natans and = Acro- pora palmata."

"It appears, therefore, that the species of coral itself is not a significant cause of frequency structure variations among par- rotfish feeding sounds. Whatever distinc- tions do exist are due to different species or sizes of feeding fishes or to other conditions that affect the fishes’ feeding behavior."

"Again, we find a gener- ally high level of acoustic activity associ- ated with parrotfish grazing throughout most of the afternoon hours and a total absence of such sound production during the early morning and late evening."

Observation Environment Quotes

"Hydro-Lab served as our base of opera- tions during a 7-day saturation dive (July 20 - July 27, 1971). Recordings of grazing sounds were made from within the habitat using a Sony TC 630 D tape deck and two 24 V DC amplifiers coupled with two Atlantic Research LC-10 hydrophones."

"To evaluate a technique for measuring the destructive effect of parrotfish grazing on various coral substrates, a 457-mm Rainbow parrotfish, Scarus guacamaia, was isolated in a 500-gal aquarium with several preweighed pieces of dead oven- dried coral."

Sound Name Quotes

"Spectrographic analyses of these sounds indicate a behavioral change in feeding habit with age among the species studied. Juveniles and small adults, 127-254 mm in length, feed rather superficially by rasping algae from hard substrates producing a SCRAPE sound in the process. Individuals, 305 mm or greater in length, characteristically bite the hard substrates while feeding producing a CRUNCH which differs from the SCRAPE temporal and frequency structure."