The name "sturgeon" refers to any fish in the family Acipenseridae. This family has existed since the upper Cretaceous Period and still continues to live today. Like other living fossils, these fish live long and mature late. With some species reaching lengths of seven meters, these bottom-feeders are quite large creatures. They mainly stick around river deltas and estuaries, but migrate upstream for spawning. Unlike other bony fishes, sturgeons have cartilaginous skeletons and are covered in skin adorned with bony scutes rather than scales. They have four barbels - sensory organs - preceding their mouths that they use to navigate by dragging them along the ground. Sturgeon feed upon shells, small fish, and crustaceans by using their mouths to suck the food up, but without teeth, they cannot seize prey. They often live to sixty years old (though some have been found over 100) and spawn for the first time around twenty; due to this, many species are under threat from overfishing and environmental pollution. As such, most of the sturgeon family is at risk of extinction, rendering them more endangered than any other family. Without ceasing illegal fishing, humans may see the end of the sturgeon come quicker than it should naturally.