Secretion is the process of elaborating, releasing, and oozing chemicals, or a secreted chemical substance from a cell or gland.In contrast to excretion, the substance may have a certain function, rather than being a waste product.ecretion is the process of elaborating, releasing, and oozing chemicals, or a secreted chemical substance from a cell or gland.
The oldest shark fossils. The oldest fossilized evidence of prehistoric sharks comes from shark-like scales that date to 455 million years ago during the Ordovician Period, in Colorado. Some paleontologists do not agree that these scales are sufficiently shark-like to pronounce them sharks.
15. Shark teeth were recently discovered to contain fluoride. 16. Sharks do not suffer from cavities. 17. The inside of shark and human teeth contains a soft mineral known as dentin. 18. The coating of shark teeth is acid resistant and less water soluble than our teeth. 19. Shark teeth and human teeth are equally as hard. 20. Even though many sharks have sharp teeth that could inflict a wound to humans, sharks should always be treated with respect.