Final answer:
Phytoplankton and zooplankton are the most abundant forms of marine life in aquatic ecosystems. They play a crucial role as food sources and in the carbon cycle.
Step-by-step explanation:
The most abundant forms of marine life in aquatic ecosystems are phytoplankton and zooplankton. Phytoplankton are tiny, single-celled organisms that perform photosynthesis and produce half of the world's oxygen. Zooplankton, on the other hand, are small animals that feed on phytoplankton.
These organisms play a crucial role in marine ecosystems. Phytoplankton are the main producers of food and energy, forming the base of the marine food chain. Zooplankton, in turn, are an important food source for higher trophic levels, such as small fish and whales.
The abundance of phytoplankton and zooplankton not only supports the entire marine food web, but also contributes to the global carbon cycle, helping regulate the Earth's climate.