Members Reports and Photos
SATURDAY 1st march 2014
PRAEGER CENTRE, National botanic gardens
LEADERs: maria long & declan doogue
session: Maria Long: The Vertigo snail family
has some good legislation supporting the conservation of wildlife, and natural
habitats. Indeed complaints from landowners and developers would lead one to the
impression that the commercial development of the entire country is stymied by
those of us (do-gooders and tree-huggers) interested in the well-being of our
naturally-occurring plants and animals, and the places they need for survival.
fact it is a relatively rare occurrence for an infrastructural or commercial
project to be seriously affected by the enforcement of conservation legislation.
Two unconnected famous occasions when this did happen were when a major road
scheme through County Kildare and a commercial recreational development in
County Clare fell foul of tiny Whorl Snails of the family Vertigo.
Long has taken part in several studies and surveys of these and gave us a
‘Praeger Day’ morning introduction to them on March 1st 2014. We
have eight species of Vertigo in Ireland, and all but two are in real
danger of extinction, mostly due to draining of their habitat and all are
considered ‘rare’ though some are relatively widespread.
of these species are found in wetland habitats, some preferring wet flushes,
other swamps or fens. Some species are even found on shaded rocks and walls,
where they should not be confused with young Lauria or Leiostyla
species among others whose adults are much bigger. The fully-grown adult Vertigos
are usually about 2–3 mm in size, so they are not easy to see with the naked
eye unless you are lucky and come across one that is on the move. Sieving moss
and detritus from the margins of water-bodies and hand-searching at the base of
reed-beds are probably most effective methods of finding them. In Autumn Vertigo
moulinsiana climbs high up reeds and may be found there.
explained that naming these endearing little creatures to species level is
possible using a good handlens and a lot of experience and habitat knowledge,
but it is usually preferable to get them under the microscope
of the shell are used: whether they coil sinisterly or dextrally, the shape of
the opening or mouth, the number and positioning of ‘teeth’ around the
mouth, as well as the relative size of the whorls and the nature of any
sculpturing on the surface. Colour can also be used, but less reliably.
Afternoon Session: Declan Doogue: Capturing and identifying water-snails
explained how the recent flooding of river valleys following the very wet
winter, provide an opportunity to sample the fauna, especially the fresh-water
molluscan fauna of the rivers. Debris from the river margins and beds is washed
up and ‘beached’ at areas where the river bends or meanders or otherwise
loses its ability to carry debris. Among the deposits will be found a large
amount of ‘dead’ snail-shells which being light is carried well up onto dry
land. Samples can be gathered for later drying.
dried-out flotsam can be put through a series of different-sized sieves. The
material captured at each sieve is examined for snail-shells and other molluscs
which can be saved for later identification. The most interesting small snails
and bivalves are often found by examining the final, finest sample that makes it
all the way through the sieves. This should be examined using good light and
some sort of magnification.
and some members had brought along some samples and these were sieved and
examined to demonstrate the technique.
main disadvantages to this method are that although you can be reasonably sure
that all of your specimens lived in the river or its close environs, it is not
useful for mapping schemes based on a grid system as you cannot ascertain how
far any specimen has been swept along the river. This and sorting that occurs by
water-transport makes even relative studies in population values impossible to
a tool to collect samples of water molluscs to be used for teaching or learning,
however, it is a very easy to use method. But beware of land snails that might
have fallen in while alive, or been gathered by the flood along the
‘dry-land’ floor of the river valley!
Atlas of Molluscs Freshwater Bivalves Non-Marine Freshwater Bivalves
Aquatic Snails Planorbis carinatus Lymnaea stagnalis
Lymnaea peregra Royal Canal Land Snails
Discus rotundatus Vertigo shell nomenclature
Columella aspera (top) & C. edentula (bottom)
A. Vertigo substriata (left) & V. pygmaea (right) B. Vertigo moulinsiana (left) & V.antivertigo (right)
Leiostyla anglica (top) & Lauria cylindracea (bottom)
Photos © P Lenihan
Return to top