Pond life / by Edward C. Ash.

  • Edward C. Ash
Date:
[1913]
Catalogue details

Licence: In copyright

Credit: Pond life / by Edward C. Ash. Source: Wellcome Collection.

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    mouth opens, and the little creature now feeds on water- plants. The external gills become less evident, and even- tually vanish. In the meanwhile internal gills have been formed, and these gill slits are covered by a thin skin. In appearance the creature has made great changes. The tail is now “ a thing to be proud of,” very different to that of the young tadpole, and during this period, which is roughly six weeks, the internal arrangements are very similar to those of a fish. Up to this time the tadpoles seldom trouble to come to the surface; the blood in the gills and the water containing air meet, except for fine membranes, and thus an interchange of gases takes place. But now the tadpole’s habits alter ; it will be seen to frequently swim to the surface in order to breathe, for the lungs are being formed, and although the gills still remain yet they no longer function as previously. Gradually the gills atrophy, the eyes become larger, the lungs more powerful, the digestive organs completely changed, the tail becomes shorter and shorter, the feet webbed, and the little creature with a stump of a tail evinces great eagerness to escape out of the water. Occasionally tadpoles grow very large before forming their limbs, or it may happen that the creature remains small although maturing. Tadpoles are queer little creatures. They are very gre- garious, loving to crowd together for no obvious reason. Sometimes they are only too pleased to swim singly, but occasionally nothing can be too crowded. Then they behave in a similar manner to a crowd attempting to board a tramcar, on the way to a football match. In fact, they rush and push until one wonders that they do not injure themselves in their violent struggles. Tadpoles evince some intelligence, and are most expert dodgers when occasion needs. The poor little creatures are always in trouble. Firstly, the enormous num- bers means a possible shortage of food, and, in addition, they have many enemies ; water-beetles, even the smallest, destroy large numbers, the larva of Dytiscus will kill a score or more a day. Even leeches will seize them, and more than one Nema- tode worm passes part of its life history within the body of the tadpole. The adult Rana becomes active early in the morning and towards evening. During the day it hides away either in the water, beneath stones, or under banks. Its food consists of insects, which it captures by means of its tongue, used with great rapidity. The body is enclothed in a loose skin, which
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