Xenophyophora

Xenophyophora are a group of giant, single-celled organisms belonging to the protist kingdom, specifically classified within the class Xenophyophorea. These fascinating creatures are exclusively marine and are found in the deep sea, inhabiting the abyssal plains and trenches of oceans worldwide. They are notable for their immense size, with some individuals reaching several centimeters in diameter, making them among the largest known single-celled organisms.

These organisms are characterized by their complex test, a porous external shell made of agglutinated sediment particles, such as mineral grains and the remains of other organisms like foraminifera. The xenophyophore secretes an organic cement to bind these particles together. Inside the test, the cytoplasm is highly organized, containing numerous nuclei and specialized organelles.

Xenophyophores are deposit feeders, consuming organic matter that settles on the seafloor. They create trails or burrows as they move and feed, influencing the benthic environment. Their distribution is wide, but they are particularly abundant in areas with high organic flux, such as near hydrothermal vents or under productive surface waters. Despite their size and widespread presence in the deep sea, xenophyophores were historically poorly understood due to the challenges of studying deep-sea environments. Current research focuses on their ecology, reproduction, and the unique adaptations that allow them to thrive in the extreme conditions of the deep ocean.