Red kangaroo has the ability to freeze the development of an embryo until the previous joey is able to leave the pouch. This is known as diapause, and will occur in times of drought and in areas with poor food sources. The composition of the milk produced by the mother varies according to the needs of the joey. In addition, red kangaroo mothers may "have up to three generations of offspring simultaneously; a young-at-foot suckling from an elongated teat, a young in the pouch attached to a second teat and a blastula in arrested development in the uterus". The kangaroo has also
What Is This Thing Called Love? (short story) other, and wind up engaging in reproductive activities after all. What Is This Thing Called Love? (short story) "What Is This Thing Called Love?" is a science fiction short story by Isaac Asimov. The story was requested by Cele Goldsmith Lalli, editor of "Amazing Stories", as a satire of an article in "Playboy" called "Girls of the Slime God" which had suggested that pulp science fiction stories were concerned with aliens and sex. The story appeared in the March 1961 issue of "Amazing" as "Playboy and the Slime God", but Asimov later retitled it "What Is This Thing Called Love?"