Are There Carnivorous Plants in the Sea?

Carnivorous or mixotrophic plants are well-known on land, adapted to specific environments with acidic soils, low nutrients, high humidity, and precise temperature ranges. However, in the sea, numerous mixotrophic microalgae, often unseen without a microscope, feed on live prey. These marine mixotrophs have a broad range of prey, including other algae, and employ mechanisms such as venomous spears or toxin release to immobilize and kill. In the marine ecosystem, there are also non-constitutive mixotrophs—organisms with plant-like characteristics acquired by capturing plant prey and incorporating chloroplasts for photosynthesis. While very few multicellular animals possess this ability, unicellular organisms like ciliates, dinoflagellates, foraminifera, and others are the primary kings of non-constitutive mixotrophy in the sea. Despite the widespread occurrence of mixotrophy, much remains unknown about the factors influencing it in the marine environment, and understanding its significance in trophic food webs is still a subject of ongoing research.