Vertebrate Classes


About four hundred million years ago, the primary bony fish appeared. Early bony fish advanced into trendy ray-finned and lobe-finned fish. The earliest vertebrates were jawless fish, just like residing hagfish.

The kingdoms divide up life into big groups like vegetation and animals. Under the kingdoms are extra divisions which would be like fiction, non-fiction, mystery, and so forth. Finally, you get to the species, which is type of like getting to the book in the library.

In mammals, males have two ducts related to every teste — the epididymis and ductus deferens. Snakes lack epidiymides and the sperm are simply transported from the teste by way of the ductus deferens to the cloaca. The male also has organs known as “hemipenes” which might be situated posterior to the cloacal opening. The hemipenes are paired copulatory organs, and they are both fully practical, though solely separately is used to switch … Read More

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