TOSHIAKI J. HARA
108
capacity, Little is known concerning the chemistry of the alarm substance.
It was suggested that the alarm substance was a pterine and close to
isoxanthopterine ( Huttel, 1941; Huttel and Sprengling, 1943). These
authors called it ichthiopterine. There is evidence, however, that ichthiopterine is not identical with alarm substance (Schutz, 1956; Pfeiffer,
1967). It was also pointed out that alarm substance was not volatile although very soluble in water. Several amino acids and amines perceived
by parasitic Petromyzon marinus were chemically separated from the
body odor of brook and brown trout (Kleerekoper and Mogensen, 1959,
1963). From histological observation, on the other hand, Pfeiffer (1960)
showed that the alarm substance is produced in specialized epidermal
cells (alarm substance cells), which do not open onto the surface but
only release their contents when the skin is injured. These cells are found
in all species which show a fright reaction. The fright reaction appears
at a certain stage of the growth of fishes regardless of their prior
experience and does not develop until some time after the alarm substance
is formed in the skin (Schutz, 1956; Pfeiffer, 1983a).
A predator odor capable of eliciting a fright reaction in local prey
species was found in three North American predatory fishes (Lepomis
macrochirus, Mkropterus punctulutus, and Esox niger) and in two South
American fishes ( Astronotus ocellatus and Cichhoma sezlerum) . No
damage to predator skin was necessary to release the substance which
caused the alarm response (Reed, 1!369).
Only the olfactory sense is involved in the detection of the alarm
substance. Minnows never responded to the alarm substance after the
olfactory nerve and olfactory bulb were removed (von Frisch, 1941).
Schutz (1956) observed that if the excited movements of fish showing
the fright reaction could be seen by other minnows, even though separated by glass walls, a typical reaction could be visually transferred
without the presence of the alarm substance. Thus, under certain conditions, the movements associated with the fright reaction could initiate
a reaction in fish which had not been exposed to the alarm substance.
From observations with 60 species of Ostariophysi and 91 species (44
families) of non-Ostariophysi ( von Frisch, 1941; Schutz, 1956; Pfeiffer,
1962, 1963a, 1967)) it may be concluded that the fright reaction exists
only in the Ostariophysi and is associated with this group of fish and not
with any particular habitat or type of social behavior. The reaction is
certainly absent in some species in Serrasalminae and Mylinae. The
Mexican blind cave fish, Anoptichythys jordani, does not react to its own
skin extract, although the fish does have the alarm substance. Furthermore, although the fright reaction is species specific, a marked interspecific reaction has been observed (Pfeiffer, 1963a). However, the
108
capacity, Little is known concerning the chemistry of the alarm substance.
It was suggested that the alarm substance was a pterine and close to
isoxanthopterine ( Huttel, 1941; Huttel and Sprengling, 1943). These
authors called it ichthiopterine. There is evidence, however, that ichthiopterine is not identical with alarm substance (Schutz, 1956; Pfeiffer,
1967). It was also pointed out that alarm substance was not volatile although very soluble in water. Several amino acids and amines perceived
by parasitic Petromyzon marinus were chemically separated from the
body odor of brook and brown trout (Kleerekoper and Mogensen, 1959,
1963). From histological observation, on the other hand, Pfeiffer (1960)
showed that the alarm substance is produced in specialized epidermal
cells (alarm substance cells), which do not open onto the surface but
only release their contents when the skin is injured. These cells are found
in all species which show a fright reaction. The fright reaction appears
at a certain stage of the growth of fishes regardless of their prior
experience and does not develop until some time after the alarm substance
is formed in the skin (Schutz, 1956; Pfeiffer, 1983a).
A predator odor capable of eliciting a fright reaction in local prey
species was found in three North American predatory fishes (Lepomis
macrochirus, Mkropterus punctulutus, and Esox niger) and in two South
American fishes ( Astronotus ocellatus and Cichhoma sezlerum) . No
damage to predator skin was necessary to release the substance which
caused the alarm response (Reed, 1!369).
Only the olfactory sense is involved in the detection of the alarm
substance. Minnows never responded to the alarm substance after the
olfactory nerve and olfactory bulb were removed (von Frisch, 1941).
Schutz (1956) observed that if the excited movements of fish showing
the fright reaction could be seen by other minnows, even though separated by glass walls, a typical reaction could be visually transferred
without the presence of the alarm substance. Thus, under certain conditions, the movements associated with the fright reaction could initiate
a reaction in fish which had not been exposed to the alarm substance.
From observations with 60 species of Ostariophysi and 91 species (44
families) of non-Ostariophysi ( von Frisch, 1941; Schutz, 1956; Pfeiffer,
1962, 1963a, 1967)) it may be concluded that the fright reaction exists
only in the Ostariophysi and is associated with this group of fish and not
with any particular habitat or type of social behavior. The reaction is
certainly absent in some species in Serrasalminae and Mylinae. The
Mexican blind cave fish, Anoptichythys jordani, does not react to its own
skin extract, although the fish does have the alarm substance. Furthermore, although the fright reaction is species specific, a marked interspecific reaction has been observed (Pfeiffer, 1963a). However, the