Allometric growth of the proglottids and strobila of the tapeworm, Hymenolepis diminuta

Abstract

Hymenolepis diminuta adults were killed and fixed in fully extended positions, and the total lengths of the strobilae, numbers of proglottids, and distances of proglottids along the strobilae were determined. The relationship of proglottid number to distance along the strobila was exponential. Beginning at proglottid 100 (P100), the lengths and widths of proglottids at 100 proglottid intervals were determined, and the surfaces areas were calculated. The relationships of proglottid length and width to proglottid number were linear, but the relationship of proglottid number to surface area (SA) was exponential. The volumes of proglottids were calculated, and the relationship of volume (V) to proglottid number was exponential. The relationship of surface area to volume ratio (SAVR) to proglottid number was exponential; at the anterior end of the worm (P100), the SAVR was 14.6, while at the posterior end of the worm (P1300) the ratio was 4.2. A single exponential equation describing the relationships among proglottid number, SA, and V was derived.