Zoochlorella is a genus of alga comprising one species, Z. parasitica. The term Zoochlorella (plural zoochlorellae) is sometimes used to refer to any green alga that lives symbiotically

Symbiosis

Symbiosis is close and often long-term interaction between different biological species. In 1877 Bennett used the word symbiosis to describe the mutualistic relationship in lichens...

 within the body of a freshwater

Freshwater

Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...

 or marine invertebrate

Invertebrate

An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...

 or protozoan. Zoochlorellae and zooxanthellae may both be found in the Pacific coast sea anemones Anthopleura elegantissima and Anthopleura xanthogrammica

Anthopleura xanthogrammica

Anthopleura xanthogrammica, or the Giant Green Anemone, is a species of intertidal sea anemones, of the family Actiniidae.Other common names: Green Surf Anemone, Giant Green Sea anemone, Green Anemone, Giant Tidepool Anemone, Solitary Anemone, and Rough Anemone...

.

The analogy between Zoochlorella and Chromatophores has been used by the botanist Konstantin Mereschkowski

Konstantin Mereschkowski

Konstantin Mereschcowsky was a prominent Russian biologist, botanist and advocate of eugenics active mainly around Kazan, whose research on lichens led him to propose the theory of symbiogenesis - that larger, more complex cells evolved from the symbiotic relationship between less complex ones...

 in 1905 to argue about the symbiotic origin of the chromatophores.

Zoochlorellae are responsible for the green

Green

Green is a color, the perception of which is evoked by light having a spectrum dominated by energy with a wavelength of roughly 520–570 nanometres. In the subtractive color system, it is not a primary color, but is created out of a mixture of yellow and blue, or yellow and cyan; it is considered...

ish color

Color

Color or colour is the visual perceptual property corresponding in humans to the categories called red, green, blue and others. Color derives from the spectrum of light interacting in the eye with the spectral sensitivities of the light receptors...

 of sea anemone

Sea anemone

Sea anemones are a group of water-dwelling, predatory animals of the order Actiniaria; they are named after the anemone, a terrestrial flower. Sea anemones are classified in the phylum Cnidaria, class Anthozoa, subclass Zoantharia. Anthozoa often have large polyps that allow for digestion of larger...

 tentacle

Tentacle

A tentacle or bothrium is one of usually two or more elongated flexible organs present in animals, especially invertebrates. The term may also refer to the hairs of the leaves of some insectivorous plants. Usually, tentacles are used for feeding, feeling and grasping. Anatomically, they work like...

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