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 researchers also conducted hardness tests, and found that despite the shark teeth being made of a naturally harder mineral, they were not harder than human teeth; this because the crystal structure of human teeth has a pattern arrangement more suited to hardness.ole rat dental structure similar to a shark. (PhysOrg.com) -- Sharks are capable of continually growing new teeth. As the teeth age, they fall out and new ones move forward similar to that of a tooth conveyor belt.