Overall numbers
There is no accurate number of invertebrates found in Scotland and Scotland’s seas. There are thought to be around 14,000 insect species known from Scotland, other invertebrates, including marine species, may add another 10,000, making a total of around 24,000 invertebrate species.
Endemic species
There are currently four species, termed endemic species, that are known from Scotland and no where else in the world. These are:
Ceratophyllus fionnus – a parasitic flea found in Manx shearwaters nests on the island of Rum only.
Cixius caledonicus – a cixiid bug which is thought to live under rocks in grassland, possibly with a preference for calcareous areas. There are three records for this species from the Lothians and Tayside, all of which were made prior to 1960. It is possible that this species is now extinct.
Protapion ryei – a weevil found on the Western and Northern Isles where it is associated with grassland, machair and brownfield sites with red clover (Trifolium pratense). This species is likely to be adversely affected by development of brownfield sites and grasslands being invaded by scrub.
Anaspis septentrionalis – a scraptid beetle known from specimens collected in 1976 near Aviemore. It is thought that this species may now be extinct.
In addition, the February red stonefly (Brachyptera putata) is now only found in larger rivers in the north of Scotland. Historically it was also found in the River Wye in Herefordshire however there have been no recent records from here. This species is affected by poor water quality, the acidification of head waters and river management schemes.
Species for which Scotland is a stronghold
In addition to these endemic species, Scotland also represents a stronghold for many species. In 1997 it was estimated that approximately 1300 Scottish insect species are, within the British Isles, restricted to Scotland. These species include the Northern emerald dragonfly (Somatochlora arctica), the mason bee Osmia uncinata and the Chequered skipper butterfly (Carterocephalus palaemon). Recent work has also indicated that Scotland is the European stronghold for the red pine hoverfly (Callicera rufa).
Keystone species
Some invertebrate species can be classed as keystone species whose loss from an ecosystem would have a major effect on other species populations and ecological processes in that system. These include the Wood ants (Formica exsecta, Formica sanguinea, F. aquilonia and F. lugubris) which influence the distribution, abundance and community structure of many other species of invertebrates as well as dispersing large numbers of plant seeds.
Invertebrates such as the brown shrimp (Crangon crangon) and Krill (Meganyctiphanes norvegica) ‘power’ marine ecosystems. They provide food for fish and marine mammals such as the Basking shark. Marine invertebrates are also responsible for some of the most important marine habitats. Flameshell reefs are created by the mollusc Limaria hians, and the west coast of Scotland is home to the majority of this habitat in the United Kingdom. These spectacular reefs can support over 250 species of plants and animals including sponges, worms, molluscs and crustaceans.
