[5] In this species, the scolex is short and equipped with two suckers, and the proglottids develop in groups of three different sizes – small, medium and large – which are repeated throughout the length of the strobila (segmented body).

[4] In one study by the Russian zoologist A. Skryabin, who described T. calyptocephalus in 1961, the largest proglottids were 5 cm (2 in) wide and contained fourteen gonads.

When sufficiently mature, the terminal proglottids are shed, being expelled from the host with the whale's fæces.

[4][5] Compared with their free-living relatives, parasites tend to be more fecund, and the whale tapeworm is likely to produce billions of eggs during its lifetime.

[8] Considering why the worms should have evolved this enormous fecundity, Gerald D. Schmidt and Larry S. Roberts (1977) reflected that "There are few whales and the ocean is large".