Marine phytoplankton come in different sizes, from tiny to large. Smaller ones may grow faster, but larger ones are better at surviving. It's debated whether small phytoplankton grow the fastest or if there's a peak at a medium size. Small ones are good at getting nutrients in low amounts, while big ones are better at using sudden nutrient boosts. Larger phytoplankton sink more easily. Small ones are eaten by tiny creatures, while big ones are eaten by larger ones. Different sizes of phytoplankton are found in marine and lake environments. Size is crucial for phytoplankton success, but being small doesn't always mean being better.