File:Aquatic life (1916-1917) (19559105698).jpg

Title: Aquatic life
Identifier: aquaticlife219161917baus (find matches)
Year: 1916-1917 (1910s)
Authors: Bausman, Joseph E
Subjects: Aquariums; Fish culture
Publisher: Philadelphia : J. E. Bausman
Contributing Library: Harvard University, Museum of Comparative Zoology, Ernst Mayr Library
Digitizing Sponsor: Harvard University, Museum of Comparative Zoology, Ernst Mayr Library

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Minute InKabitants of Aquaria PERRY BRUCE CLARK, San Francisco Aquarium Society The rotifers, or wheel animalcules, are very interesting animals, very transpar- ent, and their structure is easily seen with a microscope. They are small, measuring one-thirtieth of an inch, but are highly organized. Circular discs at the anterior or mouth end, from which project a row of cilia which are in con- stant motion, greatly resemble revolving wheels. These cilia or hairs sweep the food into the mouth, and also serve as propellers for swimming. It may also move after the manner of the so-called measuring worm by loping, that is, at- taching the head and then moving the tail up to it. The rotifers multiply by means of eggs. It has been stated that these eggs are very resistant, and may under favorable conditions develop after hav- ing been in the dry state for a number of years. At times rotifers may be col- lected in quantity and form a valuable food f^^ fisli just out of the egg. Nearly all the live foods used for young fishes belong to the class Crust, acea, which contains some very small ani- mals, as well as some large ones. As the name implies, they are shell-bearing ani- mals. The body is segmented, though in some of the smaller species it is very in- distinct, in this class belong the lobster, crab, shrimp, crayfish, and smaller form such as Gaiuarus, Daphnia, Cyclops and Cyrpris. Of these the best for fish food is Daphnia, the body of which is flat- tened, indistinctly segmented, and en- closed in a bivalve carapace or shell. The prominent antennae give it a bizarre ap- pearance as it jerks its way through the water; they look like abnormally long arms waved above its head. It multi- plies rapidly in a very curious manner. During the summer the female produces eggs, which, without fertilization by the male, mature in the brood pouch into perfect animals in about four days. A
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/l/f/!otvs s/toiv J3/f<ecr/o/v of Daphnia pulex (greatly enlarged) Original Drawing by Frank J. Myers few days after leaving the mother they, too, reproduce in like manner. In the fall of the year the much smaller males appear, and then sexual reproduction takes place. The female now lays winter eggs, having a thick covering, which pro- tects them through the cold months until they hatch. Daphnia live upon decaying

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