Peatland wildlife
Snails and Crustaceans
Peatland pools are home to a diverse range of snails and crustaceans,
including:
| Pond snail |
 |
Pond snail
Pond snails have a distinctive shell that coils up to an apex
at its centre. This houses a soft muscular foot and an organ
filled sack which remains permanently inside the shell. Their
shells are usually a shade of brown with few external distinctions
between species. The behaviour of pond snails varies little
and all feed on plant matter and algae which they scrape away
using a special tongue embedded with teeth called a radula.
They lubricate their way with secreted mucus leaving a slime
trail wherever they go. They lay their eggs in a protective
mass of jelly and attach them to plants or any other underwater
structure. While they can tolerate the slight acidity of bog
pools snails are not present in very acidic ponds. The diversity
and numbers of pond snails increases in pollution free waters,
which are rich in plant life.
| Ramshorn
snail |
 |
Ramshorn snail
Ramshorn snails vary in size considerably with the largest
being the great ramshorn snail at up to 30mm in diameter. The
shell coils in a flat spiral, unlike the pond snail whose shell
spirals up to a point. Ramshorn snails are widespread and common,
inhabiting small, still, weedy ponds and drains.
The snail's digestive organs are housed permanently within
the shell, while it moves about using a large muscular foot
which contracts in waves to push it forward whilst secreting
the characteristic slime trail to ease its passage. They can
retract the foot if threatened. These snails graze on algae
by scraping rocks with a special tongue with embedded teeth
called a radula. Their shells are various shades of brown with
a reddish tinge caused by the presence of haemoglobin. This
chemical functions in the same way as it does in human blood,
where it absorbs oxygen from the surrounding liquid. This means
that ramshorn snails do not have to surface as often to breathe
but can absorb much of their oxygen from the water. The lay
their eggs in a protective mass of jelly on plants or any other
underwater structure.
| Water flea |
 |
Water flea
Water fleas are small crustaceans found in lakes ponds and
pools, usually between 0.5mm and 4mm long. The thorax, with
5 or 6 pairs of limbs, and the abdomen are enclosed inside a
shell-like carapace. The head has a single large eye and antennae
with many bristles that the water flea uses for swimming. They
swim with a characteristically jerky motion and it is because
of this they are known as fleas.
Water fleas eat microscopic plants and in turn act as a food
source for many other animals. Some species can be found throughout
the year whereas others are present only during the warmer months.
In the early part of the year only females are present, and
they reproduce without fertilisation to produce large numbers
of offspring. Only when winter is near or if the pond is in
danger of drying up do males appear and fertilise the thicker-shelled
winter eggs produced at this time. These eggs are resistant
to freezing during the winter months when the adults die off,
and can be carried by wind or floodwater.
| Water louse |
 |
Water louse
The water louse, or water slater, has a flattened body and
looks similar to their close relation, the terrestrial woodlouse.
They are bottom dwellers, crawling through and feeding on the
detritus and debris that collects there. The parallels with
the woodlouse are strong as it favours the dead leaves that
gather in stagnant or slow-moving water. They are up to 15mm
long, greyish-brown in colour and are unable to swim freely.
The male is much larger and often carries the female about clasped
to his front. The body is made up of seven distinct segments,
each with a fairly unspecialised pair of appendages, although
the front pair are more adapted for grasping. They are undoubtedly
primitive creatures but play an important role in the bog pool
ecosystem as a food source for the many predators that live
there.
| Freshwater
shrimp |
 |
Freshwater shrimp
Freshwater shrimps are crustaceans of the same class as common
shrimps, prawns, crabs and crayfish. They feed mainly on detritus
and use their legs either to walk or waft through the water.
Although they swim with a straightened posture, they are strongly
curved when hiding amongst the detritus and vegetation of their
home. They are typically between 15mm and 30mm long with the
male larger than the female. They are generally a pale olive
colour, although this can vary from grey to reddish-brown. They
can tolerate a wide range of aquatic conditions and therefore
are widespread and common.
