Zebra larva vision, brains and responses
Dallas E. Weaver, Ph.D.
dweaver at crl.com
Mon Sep 30 18:20:12 EST 1996
We have observed that our zebra larva at high density (>100/l) in 1000
liter tanks appear to try repelling each other and are attracted to
the surface. If they can't get away from their relatives they use up
their energy reserves faster that they eat, hence they die.
In thinking about this observation, it appears that they are
preprogramed to avoid other fish and that this program can interfer
with the feeding response. We were also thinking about the vision
system of these larva which should only have 2-D information. Without
knowledge of distance, there is no way that the larva can know whether
what he sees is another small fish (no threat) or a larger fish futher
away. If it is a larger fish and he moves on a food animal, he would
be eaten himself (creates an interesting choice). When he is older
with a more complicated brain, he could obtain information on size
from fin and gill movement rates on a target that he sees.
On some other larval fish, adding clay to the water improves survival.
Could the same vision problem be solved by the clay with will allow a
distance measurment, even with a simple brain. (water color doesn't
Is anyone working on larval brains and vision. This could be very
relevant to larval aquaculture on many species. Please contact if you
are playing with this class of problems.
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