CHECK IT OUT
The creatures living in puddles and ponds
live in all kinds of ways and in all kinds
of places. Algae usually float freely in
the water in order to get as close as
possible to the light. Water fleas paddle
themselves around and use their legs to
filter out algae and microorganisms.
Some animals can be seen with the naked
eye, while others are only visible under
the microscope.
A fearsome pond predator you might find
is a freshwater polyp called a hydra. It
has tentacles that it uses to fish for food,
and it also possesses tiny, poison-tipped
harpoons with which it shoots its prey
upon contact, wounding or killing it.
While some polyps are visible with the
naked eye — some are up to 2.5 cm long
— their prey can only be seen under the
microscope.
The World of Microbes
in Our Water Systems
Gateway to the Microcosm
TIP!
First study t
he water sa
mples
with your na
ked eye. A lo
t of
specimens, s
uch as wate
r fleas
and some di
atoms, can e
asily be
seen withou
t magnificat
ion. If
your water s
ample is ver
y cloudy,
just let it sit f
or a while. F
ine sand
or silt partic
les will sett
le to the
bottom of th
e sample ve
ssel. Then
you will be a
ble to see th
e freely
swimming c
reatures qui
te easily,
and you can s
uction them u
p with
the pipette a
nd place the
m on
your slide fo
r observatio
n.
29
“Hydra” freshwater polyp
