. Evolution and animal life; an elementary discussion of facts, processes, laws and theories relating to the life and evolution of animals . ife fixed. Instead of go-ing on and developing intoa fishlike creature, it losesits notochord, its specialsense organs, and otherorgans; it loses its com-plexity and high organiza-tion, and becomes a mererooted bag with a doubleneck, a thoroughly de-generate animal. A barnacle is another example of degeneration through quiescence. The barnaclesare crustaceans related most nearly to the crabs and young barnacle just from the egg (Fig. 225, /) i
. Evolution and animal life; an elementary discussion of facts, processes, laws and theories relating to the life and evolution of animals . ife fixed. Instead of go-ing on and developing intoa fishlike creature, it losesits notochord, its specialsense organs, and otherorgans; it loses its com-plexity and high organiza-tion, and becomes a mererooted bag with a doubleneck, a thoroughly de-generate animal. A barnacle is another example of degeneration through quiescence. The barnaclesare crustaceans related most nearly to the crabs and young barnacle just from the egg (Fig. 225, /) is a six-legged, free-swimming nauplius, much like a young prawn orcrab, with single eye. In its next larval stage it has sixpairs of swimming feet, two compound eyes, and two largeantennaB or feelers, and still lives an independent, free-swim-ming life. When it makes its final change to the adult con-dition, it attaches itself to some stone or shell, or pile orships bottom, loses its compound eyes and feelers, developsa protecting shell, and gives up all power of locomotion. Itsswimming feet become changed into grasping organs, and it. FIG. 224.—The sea squirt or tunicate. PARASITISM AND DEGENERATION 365 loses most of its outward resemblances to the other membersof its class (Fig. 225, e}. Certain insects live sedentary or fixed lives. All the mem-bers of the family of scale insects (Coccida?), in one sex atleast, show degeneration that has been caused by of these coccids, called the red orange scale, is very
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