Referring to Growth Rate(r) versus Carrying Capacity(k) of a particular species. Growth Rate is how efficiently a species grows in population, versus Carrying Capacity, the number of said species able to coexist in one habitat. Organisms practicing r selection strategy tend to have shorter life spans, gestation and growth periods, producing many offspring which they care for little. An example would be most insects, fish and reptiles (often smaller and/or simpler animals). Organisms practicing k selection strategy tend to have longer life spans, gestation and growth periods, producing few offspring and caring for them for a long time. Examples include: most mammals, such as humans, whales, elephants, and some birds.
In Sponges
Sponges are predominately r selected. There is essentially no interaction with a Porifera's offspring or even their mate. This is due to the fact that Porifera can produce both zygotes, meaning they can perform asexual reproduction. But even in the sexual reproduction of Porifera, they merely pump zygotes into the current and let them randomly fertilize other Porifera, similar to plants and pollination. This form of random fertilization requires sponges to release so many zygotes so densely that the sponge may appear to be smoking. This is a perfect example of a strategy for exponential population growth in species with no need for parental care.