1902 Encyclopedia > The Alps > Invertebrates of the Alps

The Alps
(Part 31)


(g) Invertebrates in the Alps

In the classes hitherto noticed the number of species peculiar to Alps is very small. This rule is reversed among the Invertebrate, especially as regards the Articulata and Mollusca. The number of insects is very great, and a considerable proportion extends to the limit of perpetual snow. Oswald Heer has pointed out several peculiarities in the insect fauna of the higher Alps. In ascending from the mountain region the proportion of the carnivorous tribes rapidly increases, and the families that feed on living vegetation matter either disappear or are much reduced in numbers. Beetles and other insects either lose their wings in the upper region, or are represented by allied wingless speci4es. Along with the tendency to lose the power of flights, a diminution of brilliancy of color appears, the prevailing hues being black or dingy grey. These peculiarities are to be explained by the fact that in the upper Alpine zone insects live under stones, and the power of flight generally proves injurious to animals liable to be carried by the wind and upward air-currents over the snow-fields, whence they are unable to return. This is often seen to occur to butterflies and a few moths, which ascends as far as the highest flowering plants. The snow-fields and glaciers are not devoid of insect life. Several species of snow-flea have been detected; and further observation will probably bring to light other minute animals living in the pools that form on the surface of glaciers, or on the snow-beds, although their activity is often interrupted by the freezing of the surface.

The Arachnida are eminently characteristic of the fauna of the high Alps, where they abound both in species and individuals. Spiders ascends to the utmost limit of vegetation, and are even to be found on the bare rocks that rise out of the snow up to a height of 11,000 feet.

Although most of the orders of Articulata are represented in the Alps by numerous forms, these are far out-numbered by the total number of European species of that class; but among land and fresh-water Mollusca the proportion is reversed, and as many as seven-eights of all the species known in middle Europe, and a large proportion of those of the Mediterranean region, have been found in the Alps. Still more remarkable is the large proportion of endemic species. In the important group of the Heliceæ fully one hundred species, or four-tenths of the whole number, are peculiar to the Alps. Between thirty and forty species only have been found in the Alpine zone, and of these but five --- Vitrina diaphana, V. glacialis, Helix glacialis, H. fœtens, and Vertigo Charpentieri. --- attain the upper limit of vegetation.

The Annulosa and Radiata of the Alps, so far as they are known, do not offer any points of special interest; and the study of the minute organisms, which have been proved to exist as high as 12,000 feet above the sea, is still in its infancy.

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