Researchers are currently facing difficulties completely differentiating the numerous species under the genus "Trichuris". When different whipworm species were discovered, the main factor used to differentiate species was the length of the spicule sheath. However, many species were eventually discovered to have similar spicule sheath lengths. Therefore, researchers began to compare other morphologies, such as the structure or orientation surrounding female sex organs of species suspected to be similar, but different. Relatively recently, studies have been conducted to differentiate similar "Trichuris" species based on mitochondrial DNA differences, a much more accurate method of distinction. However, currently a paucity of research devoted to encoding the DNA of each and every species exists. As a result, "Trichuris" species distinction is still largely based on morphological differences.