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Amphibia 3 - several weeks while increasing in size The...

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Amphibia 3 Life cycle Changes in the egg after fertilisation surface view vertical section (a) Single cell (b) Nucleus divides (c) Cytoplasm divides; 2-cell stage (d) 4-cell stage (e) 8 cells (f) 32+ cells (g) Many cells Side view Side view Side view Dorsal view Dorsal view Dorsal view Ventral view external gill mouth closed mucous gland 3 days old Attaches itself to jelly or weed with mucous gland. Inactive. 4 days old Periods of inactivity with vigorous bursts of swimming external gill tail muscles 6 days old External gills shrivelling; operculum beginning to grow over gills; actively swimming intestine visible through skin lips and jaws mucous gland operculum diagram to show operculum growing over gills 3 weeks old . External gills and mucous gland gone; swimming vigorously; stays like this for
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Unformatted text preview: several weeks while increasing in size The tadpole at first breathes through its external gills. After about 6 days a fold of skin (the operculum) grows over the gills and the internal gills take over. A small cleft (spiracle) in the operculum provides the exit for the breathing current The early tadpole adheres to pondweed with its mucous glands and rasps off the surface algae with its jaws. The long intestine is an adaptation to this herbivorous diet. Later the diet becomes carnivorous; the tadpole scavenges dead remains in the pond. They can be fed in aquaria with pieces of cooked meat (but tie the meat to a thread and remove it before its gets rotten) © D.G. Mackean operculum Blood circulation in external gill...
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