notes from DANIEL KNOPLETTER
hen we peer
into our aquar-
iums, there is
almost always
someone looking back. Af-
ter all, each of our fishes and
shrimps have a pair of eyes.
But it is not just fishes and
shrimps that look at us—there are countless eyes and
light-sensory organs in the aquarium. From rock crev-
ices and every nook and niche in the tank, we are being
observed as we stand in front of the aquarium. Lens eyes,
pit eyes, compound eyes—they are all watching us. And
we don’t even see them unless we know what to look for.
The construction of these many eyes in our aquariums
gives us an insight into evolution, because our marine ani-
mals have many different types of eyes. This is not true of
any other organ of the body. The visual organs of all the
animals in the aquarium serve pretty much the same pur-
poses, but their design and function differ wildly.Sensory organs for the
perception of light stimuli
are always an evolutionary
result of the living conditions
and requirements of the spe-
cies in question. They reflect
the principle of adaptation by
selection: any organism that,
due to a mutation, invests too much in its vision without
a reproductive advantage disappears from the gene pool.
Evolution finds ingenious solutions to problems, but at the
same time is mercilessly economical and efficient.
In this way, about 40 different eye types have emerged
over the course of the millennia. Many of them can be
studied not only in fossils, but also in the living habitat of
an aquarium, where we can see these amazing organs in
action. A little evolutionary history is demonstrated every
day in our living rooms.
Eyes open? Happy reading!KORALLE editor-in-chief Daniel KnopW
FOCUS: Photo Model
Particularly beautiful and rare coral fishes are usually very fast and
elusive, so it is difficult to take photographs of them. Photographing this
young and very pretty Longfin Anthias, Pseudanthias ventralis, which
was about 1.6 inches (40 mm) long, was a different story. I found it in the
huge Interzoo exhibition aquarium of De Jong Marinelife. Several times
during the exhibition I returned to this impressive show tank,
and each time this little fish spontaneously appeared
and posed patiently while I took its picture.D. KNOP