Dolphins do not eat phytoplankton. As carnivorous marine mammals, their diet consists entirely of other animals. Phytoplankton, conversely, are microscopic, plant-like organisms forming the base of marine food webs.
What Dolphins Really Eat
Dolphins are active predators with a diverse diet consisting of fish and squid. The specific prey items vary significantly depending on the dolphin species and its habitat. For instance, common bottlenose dolphins in oceanic environments frequently consume fish such as mackerel, herring, and cod. Some larger dolphin species, like orcas, expand their diet to include marine mammals and birds. River dolphins, living in freshwater environments, typically feed on crustaceans and small river fish.
Dolphins employ hunting techniques to locate and capture their prey. They often use echolocation, a biological sonar system, to emit sound waves and interpret the returning echoes, detecting object size, shape, and distance, even in dark or murky waters. Many dolphin species also engage in cooperative hunting, where pods work together to herd schools of fish into tight “bait balls” or trap them against shorelines or sandbars. Once prey is concentrated, dolphins take turns swimming through the dense schools to feed. Dolphins possess conical teeth suited for grasping their prey, which they typically swallow whole rather than chewing.
The Role of Phytoplankton in the Ocean
Phytoplankton are microscopic organisms, including single-celled algae and bacteria, that inhabit watery environments. These tiny entities float in the upper, sunlit layers of the ocean because they require sunlight to produce their own energy. Similar to plants on land, phytoplankton contain chlorophyll and perform photosynthesis, converting sunlight, carbon dioxide, and nutrients into chemical energy.
Phytoplankton are the ocean’s primary producers, forming the foundation for nearly all marine food webs. They play a significant role in Earth’s oxygen cycle, collectively producing an estimated 50% of the oxygen in the atmosphere. Beyond oxygen production, these organisms are crucial for the global carbon cycle, absorbing carbon dioxide from the atmosphere and transferring it through the food web or to the deep ocean when they die.
Dolphins’ Place in the Marine Food Web
Marine ecosystems are structured by trophic levels, which describe the feeding positions of organisms. Organisms that consume phytoplankton are known as primary consumers, forming the second trophic level. Zooplankton, which are tiny marine animals, are a notable example of primary consumers that graze on phytoplankton. Small fish then feed on these zooplankton, which are then consumed by larger fish.
Dolphins, as carnivores, occupy higher trophic levels, typically ranging from 3 to 5 depending on species and diet. They feed on various fish, squid, and sometimes crustaceans, several steps removed from the microscopic phytoplankton. Dolphins do not directly consume phytoplankton; they rely on a chain of energy transfer that originates with these microscopic producers.