Reproductive strategies and patterns in marine invertebrates: diversity and evolution.

Aquatic and, in particular, marine invertebrates demonstrate a wide range of sexual reproduction traits, which is unsurprising given their enormous morphological and ecological diversity. The descriptive data published on their reproduction are massive. Providing an integrated picture of their evolution, however, remains difficult due to the large number, variability, and numerous combinations of reproductive traits, as well as due to the incomplete data on the reproduction of many groups. Nonetheless, the known diversity reveals the main directions and stages in the evolution of sexual reproduction within particular clades, an important step in outlining the general patterns in marine invertebrates. The present brief overview analyzes this issue based on our current level of knowledge.