. An introduction to zoology, with directions for practical work (invertebrates). 114 INTRODUCTION TO ZOOLOGY Hiberna- tion. Enemies. Limnaea seems to spend the greater part of the winter in a state of torpor, buried in the mud at the bottom of the pond and breathing probably through its skin; it does not hibernate completely, however, and has been seen even on a day when the pond was frozen over, crawling about on the under side of the transparent ice. The water snail is preyed upon by a good many other creatures; ducks and water-shrews devour it, the carnivorous water beetle {Dyticus margina
. An introduction to zoology, with directions for practical work (invertebrates). 114 INTRODUCTION TO ZOOLOGY Hiberna- tion. Enemies. Limnaea seems to spend the greater part of the winter in a state of torpor, buried in the mud at the bottom of the pond and breathing probably through its skin; it does not hibernate completely, however, and has been seen even on a day when the pond was frozen over, crawling about on the under side of the transparent ice. The water snail is preyed upon by a good many other creatures; ducks and water-shrews devour it, the carnivorous water beetle {Dyticus marginalis)â the " shark " of the pondâfeeds on it, frogs and toads will snap it'up when small, and sticklebacks and other fish eat a great quantity of the eggs before they hatch and of the recently hatched fry. Other Common Air-breathing Water Snails. There are four chief genera of lung-breathing water snails, and there are several species of eacli genus that are very common in our ponds ; these will be now briefly enumerated and shortly characterised, so that they may be recognised when found. Belonging to the Lfmnaea. Sâ¢'^^ Livmaea are all waters nails with thin, horn - coloured, sjjirally - coiled, conical shells, and having two triangular, non-retractile ten- tacles, with an eye at the base of each. Limnaea stagnalis {the Common Pond Snail) (Figs. 61 and 65). âThis is the species fully de- scribed above. Size 1^ to 2 inches. Whorls 6 to 8, the last one relatively very large. Mouth of shell rather more than half the whole length of the Fig. 65.âThe Shells of some common species of Limnaea. L. stag., Limnaea stagnalis ; L. pal., L. palnstris; L. â par,, L. peregra ; L. aur., L. auricnlaria; L. tmnc, L. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Lulham, Rosalie B
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Keywords: ., bookcentury1900, bookdecade1910, bookpublisherlondo, bookyear1913
