Question

Spermathecal pores of Pheretima are present in
A. 5/6, 6/7, 7/8, 8/9
B. 6/7, 7/8, 8/9, 9/10
C. 1/2, 2/3, 3/4, 4/5
D. 14/15, 15/16, 16/17, 17/18

Answer 1

Hint: Pheretima is a terrestrial earthworm, which lives in burrows made in moist soil. The body of earthworms has around 100-120 small ring-like segments or metameres or somites. Earthworm exhibits true segmentation, i.e., the external segmentation corresponds with its internal segmentation.

Complete answer:
The body of earthworms is made up of distinct metameres or segments separated from each other by inter-segmental ring-like annuli or grooves. The body is made up of a series of 100-120 segments, and this external segmentation corresponds with the internal segmentation.

In Pheretima, the diverticula stores the spermatozoa and not the ampulla. As the spermatheca pores are situated inter-segmentally between segments 5/6, 6/7, 7/8 and 8/9, the spermatheca open externally by their small ducts. Each spermatheca has a flask-like shape, the main body is an ampulla which is continued into a narrow duct— the neck with a small diverticulum on its inner side. These are also known as the seminal receptacles as they store the spermatozoa from another worm during copulation. The ampulla stores nutritive substances produced by the prostate gland. But, the diverticulum stores the spermatozoa. Spermatheca are four pairs, each pair is present in the segments 6th, 7th, 8th, and 9th which are situated ventro-laterally.

Hence, the correct answer is option (A).

Note: The whole surface of the earthworm’s body is divided into many ring-like segments by a distinct series of annular furrows or grooves representing the external segmentation. The interior of the body of earthworm is divided by coelosepta or inter-segmental septa into tiny chambers representing internal segmentation. However, all the segments of its body are similar except the first and the last segments.