4. CHEMORECEPTION
107
volved in recognition was the integumentary mucus. A change in status
after fighting was chemically communicated to other bullheads.
Oshima et al. (1969b) reported that chinook salmon (Oncorhynchus
tshawytschu) showed olfactory bulbar responses to the water, which
had previously evoked only a slight response, by placing other individuals
of the same species in it. Keeping coho salmon under the same conditions
did not make the water as stimulatory.
It has been suggested that olfactory communication plays some part
in maintaining the coherence of schools. Keenleyside (1955) found that
blinded rudd, Scardinius erythrophthalmus, could detect and preferred
water that had contained other rudd but showed no such preference after
their olfactory epithelium was destroyed. Stevens (1959) observed in two
pelagic schooling fishes, Hepsitia stipes and Bathystoma rimator, that
during the day schools were maintained visually; the fish were more active and did not swim in schools at night; and their behavior was clearly
directed toward the investigation and sampling of potential food. It seems
reasonable to assume, therefore, that schools can be guided to their foods
from long distances by olfactory perception. Finally, it may be expected
that fishes swim up concentration gradients of substances excreted by their
food organisms and that schools of the same species may find each other
by this means (Stevens, 1959). Recently, Hemmings (1966a) studied the
schooling behavior of the roach, Rutilus rutilus, in relation to the role of
olfactory and visual senses; he suggested that school structure is maintained by balanced attractive and repulsive forces, the attraction
modalities involved are vision by day and olfaction by night, and the
repulsion modality is the lateral line sense.
D. Alarm Substances
Von Frisch (1938) discovered that a school of minnows, Phoxinus
laevis, showed a strong fright reaction when an injured minnow was
introduced into the school. Since then alarm substances, which communicate the presence of danger and which are produced by members
of the same species, have been extensively studied by von Frisch and his
students.
In a series of observations it was shown that the alarm substance is
released only from injured skin. Dead minnows with undamaged skin
were ineffective. Pieces of their stomach, gut, liver, spleen, and muscle
were equally ineffective. Although absolute values of the potency of the
extract could not be obtained, a solution of 0.1 g of fresh skin in 100 ml
of water was sufficient to induce fright reaction in aquaria of 25-150 liters
107
volved in recognition was the integumentary mucus. A change in status
after fighting was chemically communicated to other bullheads.
Oshima et al. (1969b) reported that chinook salmon (Oncorhynchus
tshawytschu) showed olfactory bulbar responses to the water, which
had previously evoked only a slight response, by placing other individuals
of the same species in it. Keeping coho salmon under the same conditions
did not make the water as stimulatory.
It has been suggested that olfactory communication plays some part
in maintaining the coherence of schools. Keenleyside (1955) found that
blinded rudd, Scardinius erythrophthalmus, could detect and preferred
water that had contained other rudd but showed no such preference after
their olfactory epithelium was destroyed. Stevens (1959) observed in two
pelagic schooling fishes, Hepsitia stipes and Bathystoma rimator, that
during the day schools were maintained visually; the fish were more active and did not swim in schools at night; and their behavior was clearly
directed toward the investigation and sampling of potential food. It seems
reasonable to assume, therefore, that schools can be guided to their foods
from long distances by olfactory perception. Finally, it may be expected
that fishes swim up concentration gradients of substances excreted by their
food organisms and that schools of the same species may find each other
by this means (Stevens, 1959). Recently, Hemmings (1966a) studied the
schooling behavior of the roach, Rutilus rutilus, in relation to the role of
olfactory and visual senses; he suggested that school structure is maintained by balanced attractive and repulsive forces, the attraction
modalities involved are vision by day and olfaction by night, and the
repulsion modality is the lateral line sense.
D. Alarm Substances
Von Frisch (1938) discovered that a school of minnows, Phoxinus
laevis, showed a strong fright reaction when an injured minnow was
introduced into the school. Since then alarm substances, which communicate the presence of danger and which are produced by members
of the same species, have been extensively studied by von Frisch and his
students.
In a series of observations it was shown that the alarm substance is
released only from injured skin. Dead minnows with undamaged skin
were ineffective. Pieces of their stomach, gut, liver, spleen, and muscle
were equally ineffective. Although absolute values of the potency of the
extract could not be obtained, a solution of 0.1 g of fresh skin in 100 ml
of water was sufficient to induce fright reaction in aquaria of 25-150 liters