Beginners' zoology . althoughthe brain is very all the blood goto the gills just afterleaving the Make a list of thedifferent species offish found in thewaters of your neigh- bourhood; in the markets of your town. Reproduction.— The female fish deposits the unfertilizedeggs, or ova, in a secluded spot on the bottom. Afterwardthe male fish deposits the sperms in the same place (seeFig. 225). The eggs, thus unprotected, and newly hatchedfish as well, are used for food by fish of the same and otherspecies. To compensate for this great destruction, mostfish lay (spawn) many thou
Beginners' zoology . althoughthe brain is very all the blood goto the gills just afterleaving the Make a list of thedifferent species offish found in thewaters of your neigh- bourhood; in the markets of your town. Reproduction.— The female fish deposits the unfertilizedeggs, or ova, in a secluded spot on the bottom. Afterwardthe male fish deposits the sperms in the same place (seeFig. 225). The eggs, thus unprotected, and newly hatchedfish as well, are used for food by fish of the same and otherspecies. To compensate for this great destruction, mostfish lay (spawn) many thousands of eggs, very few ofwhich reach maturity. Higher vertebrates { birds) have,by their superior in-telligence, risen abovethis wasteful methodof reproduction. Somekinds of marine fish,notably cod, herring,and salmon, go manymiles up fresh riversto spawn. It is possible that this is because they wereoriginaliy fresh-water species; yet they die if placed infresh water except during the spawning season. They go. Fig. 227. —Newly hatched Trout, withyolk-sac adhering, eyes large, and fins merefolds of the skin. (Enlarged.) FISHES 121 because of instinct, which is simply an inherited habitRivers may be safer than the ocean for their young. Theyare worn and exhausted by the journey, and never surviveto lay eggs the second time.
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectzoology, bookyear1921
