External Apertures of Pheretima
There are many apertures present in earthworm which have their own functions. Some of them are given below:
- Mouth: is a crescentic aperture, located on the ventral surface of the body, just below the prostomium and surrounded by peristomium. It is used for feeding.
- Anus: is slit-like aperture, situated in the last segment called anal segment through which undigested food and mud are pass out.
- Genital opening: Earthworm are hermaphrodites so male and female genital aperture are found in same individual.
i. Male genital aperture: A pair of male genital aperture is found on the ventrolateral side of the 18th segment through which male reproductive bodies (sperm) are discharged during copulation.
ii. Female genital aperture: A single medium female genital aperture is found on the ventral side of the 14th segment through which female reproductive bodies (ova) are discharged during copulation.
- Genital papillae or copulatory papillae: Two-pairs of circular, small and conical genital papillae are found on the ventrolateral side of each 17th and 19th They act as suckers and helps in holding the two worm during copulation.
- Spermathecal opening: Opening of spermathecal are called spermathecal pore. Four pairs of spermathecal pores are found ventrolaterally and intersegmentally between the grooves of segment 5/6, 6/7, 7/8, 8/9 respectively. They store sperm during copulation.
- Nephridiopores: Large number of very minute nephridiopores are found in all segments except first 3 segment. Metabolic waste products are released out through this pore. Clitellar region contains 2000-2500 nephridiophores while other contain 200-250.
These pores are the aperture of integumentary nephridia.
- Dorsal pores: Minute dorsal pores are present one in each intersegmental groove in the mid-dorsal surface after the 12th segment (12/13th segment) to last 2nd segment. Coelomic fluid release out through this pores to kill-harmful bacteria.
External Apertures of Earthworm
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