Which parasite has a "coccyx" or "tail-like" structure in the egg?

The correct answer is associated with Enterobius vermicularis, commonly known as the pinworm. The eggs of this parasite are characterized by their distinctive appearance, including the presence of a "coccyx" or "tail-like" structure at one end. This feature can be crucial for identification under the microscope, as it helps differentiate these eggs from those of other parasites.

Understanding the morphology of parasitic eggs is essential in parasitology as it assists in diagnosis and treatment. The eggs of Enterobius vermicularis are typically flat on one side and rounded on the other, with a prominent tail-like appendage, making them easily identifiable in stool samples or through tape testing in suspected cases of pinworm infection.

Other parasites mentioned have their own unique egg characteristics, but they lack the specific "tail-like" structure that pinworm eggs possess. This feature serves as a significant identifying trait in the context of parasitic infections and is a vital part of the diagnostic process.