But the colours which predominate in the whole mass of living creatures of all kinds are tints of green, brown, or reddish-yellow. Bright colours, such as blue, scarlet, crimson, gold, or silver are exceptional, and the colour blue is especially rare. The borrowed radiance of the inorganic world, in the form of metallic brightness, is especially a characteristic of those living gems, the humming birds; but not a few other animals also exhibit it. Thus, of birds more or less gifted with metallic radiance, though in a less degree than humming birds, may be mentioned the sunbirds, the trogons, and the beautiful family of pheasants; and many insects and many fishes shine with metallic tints. Brightness of this kind (though the leaves of a few plants have a coppery lustre) is unknown in the world of plants, in which shades of green are overwhelmingly predominant, and are universally present, except in a few exceptional forms, notably the fungi.[98] Various aquatic animals belonging to very different groups agree in possessing a perfectly glass-like transparency. Amongst them are fish which live in the ocean; for example, the Teleostean[99] fish (_Leptocephalus_), also mollusca of all kinds, including even perfectly transparent cuttle fishes.[100] There are also glass-like crustaceans,[101] and also planarians[102] and sea anemones.[103] Plants, however, never present this character, although by it they might, as well as animals, escape being preyed upon. Most fishes which inhabit the deep sea are of a dull black colour, though some are white, and the majority of all deep-sea animals, considered as a whole, are more or less decidedly coloured, many brightly so.[104] Luminosity is a character of many lowly animals, and it is the presence of minute creatures possessing this character which so often causes the spray dashed from the prow of an advancing ship to appear like a shower of sparks, while glowing bodies traverse the water beneath its surface. Many insects, such as fire-flies and glow-worms, are notoriously luminous. In the vegetable world, however, this character is very rarely present, being only so in certain fungi, some of which exhibit a wonderful luminosity. Humboldt relates that he found this to be especially splendid in mines.