What are four external features by which the ventral surface of an earthworm can be distinguished from the dorsal surface?
1 Answer
Earthworm has various openings and structures on ventral surface. Single median opening per segment is present towards the dorsal surface through which coelomic fluid oozes out.
Explanation:
Ventral side of earthworm could be identified by presence of locomotory structures, called setae . These are microscopic, present in rows.
Then there are paired openings of seminal receptacles , and male genital pores . Male genital pores are often associated with genital papillae on adjacent segments. Earthworm is hermaphroditic, so paired female genital pores are also present towards ventral side.
Number and location of ventral openings, etc may slightly vary depending on the species of earthworm. I have chosen a diagram that shows Indian species, Pheretima posthuma . It has single, median female pore in clitellar segment.
