Peatlands Wildlife
Leeches and Worms
Flatworms, which are often thought
of as terrestrial species, and leeches
are commonly found in peatland pools.
| Flatworm |
 |
Flatworm
Flatworms are extremely common and live in most permanent bodies
of water, often in large numbers. Their flattened bodies taper
towards the tail and are between 0.5mm and 35mm long. When threatened
they contract their bodies towards the head end and change direction.
They live among vegetation and feed mostly on small invertebrates,
although some of the smaller species are herbivores grazing
on algae and plant detritus. They are distinctive in appearance,
although they lack any interesting external features, apart
from some observable eyespots. They range in colour from translucent
to dark brown. While most reproduce by depositing eggs some
do so by asexual methods which include budding or routinely
tearing themselves into two pieces, each of which regenerates
into a new organism.
| Leech |
 |
Leech
Leeches are freshwater segmented worms with a distinct sucker
at each end. They can swim but spend long periods of time at
rest. Some behave as parasites sucking blood from a variety
of invertebrates and vertebrates such as fish. In these the
sucker contains a long tube which the leach extends and inserts
into the host during feeding. This injects a fluid containing
an anti-clotting factor that allows the leech to siphon off
blood. A leech may consume more than its own body weight during
a single feeding session, becoming gorged and much fatter than
a resting one. There are only two species of leech in the UK
that fed on human blood, both of which are very rare. Other
leeches use their biting and piercing mouth parts to feed on
worms, molluscs and insect larvae.
Even though leeches are hermaphrodites – that is they
have both male and female sex organs – the mating of two
individuals is necessary for fertilisation. They lay their eggs
in cocoons which they stick to stones and plant stems.
