4. CHEMORECEPTION
109
strongest response was always obtained with the alarm substance from
the same species. Interspecific reactions bear a definite relation to the
taxonomic position of the species ( Pfeiffer, 1963a).
Skinner et al. (1962) isolated the alarm substance of the top smelt
Atherinops afinis by extraction with methanol or ether from suffocated
top smelt. These extracts, when introduced into an aquarium containing
top smelt, induced a strong alarm reaction in the fish. Reaction was
species-specific. Later, however, this was denied by Rosenblatt and Losey
( 1967). Two functions, that is, warning against predators and prevention
of intraspecific predation, have been postulated to attribute to the alarm
substance, though these have been questioned recently ( Verheijen,
1962).
E. Repellents
Brett and MacKinnon (1952) found that striking reduction in the
rate of upstream migration of adult sockeye Oncorhynchus nerka, coho
0. kisutch, and spring 0. tschawytscha salmon occurred when human
hands were rinsed in the salmon ladder. Later this phenomenon was
demonstrated in all five species of migrating Pacific salmon. Of various
substances tested only dilute water rinses of mammalian skins had distinct
repellent action (Brett and MacKinnon, 1954; Alderdice et al., 1954).
Upon detecting the repellent odors, salmon swam excitedly moving in a
circle in the enclosed area, exhibiting an alarm reaction. Chemical
analysis of the properties of a repellent from human skin indicated that
only L-serine elicited a strong repellent action at extremely high dilution
(8 x lO-'O); however, the effects were neither so dramatic nor for so long
a duration as the response obtained by a hand rise (Idler et al., 1956,
Recently it has been observed that rainbow trout respond to handdipped water and to L-serine at concentrations as low as
M by recording electroencephalographic responses from the olfactory bulb
(T. J. Hara, unpublished data).
1961).
F. Orientation by Chemical Senses
Numerous investigations have attested the high acuity of the chemosensory organs in most fishes. Olfactory cues are important in the orientation of migrating fish (eels, Anguilla anguilla, and salmon, Oncorhynchus
sp.) and in the localization of spawning grounds; gustatory cues are
important in the location of distant chemical stimuli (bullheads,
109
strongest response was always obtained with the alarm substance from
the same species. Interspecific reactions bear a definite relation to the
taxonomic position of the species ( Pfeiffer, 1963a).
Skinner et al. (1962) isolated the alarm substance of the top smelt
Atherinops afinis by extraction with methanol or ether from suffocated
top smelt. These extracts, when introduced into an aquarium containing
top smelt, induced a strong alarm reaction in the fish. Reaction was
species-specific. Later, however, this was denied by Rosenblatt and Losey
( 1967). Two functions, that is, warning against predators and prevention
of intraspecific predation, have been postulated to attribute to the alarm
substance, though these have been questioned recently ( Verheijen,
1962).
E. Repellents
Brett and MacKinnon (1952) found that striking reduction in the
rate of upstream migration of adult sockeye Oncorhynchus nerka, coho
0. kisutch, and spring 0. tschawytscha salmon occurred when human
hands were rinsed in the salmon ladder. Later this phenomenon was
demonstrated in all five species of migrating Pacific salmon. Of various
substances tested only dilute water rinses of mammalian skins had distinct
repellent action (Brett and MacKinnon, 1954; Alderdice et al., 1954).
Upon detecting the repellent odors, salmon swam excitedly moving in a
circle in the enclosed area, exhibiting an alarm reaction. Chemical
analysis of the properties of a repellent from human skin indicated that
only L-serine elicited a strong repellent action at extremely high dilution
(8 x lO-'O); however, the effects were neither so dramatic nor for so long
a duration as the response obtained by a hand rise (Idler et al., 1956,
Recently it has been observed that rainbow trout respond to handdipped water and to L-serine at concentrations as low as
M by recording electroencephalographic responses from the olfactory bulb
(T. J. Hara, unpublished data).
1961).
F. Orientation by Chemical Senses
Numerous investigations have attested the high acuity of the chemosensory organs in most fishes. Olfactory cues are important in the orientation of migrating fish (eels, Anguilla anguilla, and salmon, Oncorhynchus
sp.) and in the localization of spawning grounds; gustatory cues are
important in the location of distant chemical stimuli (bullheads,