Marine biology questions help

please answer the following questions with 2 paragraphs each

Many species of animals in the sea have larval forms. These include diverse organisms such as fish, mussels, barnacles, and crabs. Speculate what some of the evolutionary advantages might be to a species that spends part of its life in a larval stage. What could be some of the risks?

What are some of the possible explanations for the adaptive significance of diurnal vertical migration? In your own words, propose at least one hypothesis that could explain these movements and how you might test it. (Don’t hesitate to re-read the commentaries for this module, the assigned text chapters, and see page 368 in your text for the importance of technology such as sonar in the discovery of the deep scattering layer.)