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.
The first reason there are so many fossilized teeth is that there are simply so many shark teeth, itâs bound to be one of the most common fossils. The reason for all those shark teeth is that sharks have multiple rows of teeth that are constantly being shed to maintain their razor sharp bite. EACH individual shark can shed more than 30,000 teeth in its lifetime.