A little wonder, every day

A sloth and its fur ecosystem

Концептуальна ілюстрація лінивця догори ногами з зеленкуватим хутром; не документальне фото. / Conceptual illustration of an upside-down sloth with greenish fur; not a documentary photograph.

Бурогорлий трипалий лінивець із видимими молями Cryptoses choloepi у шерсті. / Brown-throated three-toed sloth with Cryptoses choloepi moths visible in its fur. Photo: Kristof Zyskowski & Yulia Bereshpolova; [Wikimedia Commons file page](https://commons.wikimedia.org/wiki/File:Pyralidae-_Cryptoses_choloepi_on_Bradypus_variegatus.jpg); CC BY 2.0; downloaded 1920-pixel derivative without edits; checked 21 October 2026.

Наукова багатопанельна фігура з мікроскопічними зображеннями Trichophilus та водоростей на волосинах лінивців. / Scientific multipanel figure with micrographs of Trichophilus and algae growing on sloth hairs. Suutari et al., Figure 5 (2010), [BMC Evolutionary Biology](https://doi.org/10.1186/1471-2148-10-86); CC BY 2.0; unaltered; checked 21 October 2026.

Двопалий лінивець висить на гілці догори ногами; в описі архівного фото відзначено зеленкуватий відтінок шерсті від водоростей. / A two-toed sloth hangs upside down from a branch; the archival image description notes a greenish coat tint from algae. Photo: Warren Garst, Colorado State University Libraries via DPLA, CC BY-SA 4.0: https://creativecommons.org/licenses/by-sa/4.0/

Бурогорлий трипалий лінивець у хмарному тропічному лісі Коста-Рики. / A brown-throated three-toed sloth in Costa Rica’s cloud rainforest. Photo: Urak-Tou, CC BY 4.0: https://creativecommons.org/licenses/by/4.0/

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Концептуальна ілюстрація лінивця догори ногами з зеленкуватим хутром; не документальне фото. / Conceptual illustration of an upside-down sloth with greenish fur; not a documentary photograph.

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In many sloths, hair grows from a part along the belly toward the back—opposite the usual direction in most mammals and suited to an upside-down lifestyle; this arrangement also helps rain run off. Algae can live in grooves along the hairs, while fungi, bacteria, and small arthropods also inhabit the fur. Algae give the coat a greenish tint that may aid camouflage. The interactions in this “ecosystem” are complex and not all are well understood.

In a 2023 study, researchers sequenced short fungal DNA markers from the fur of ten two-toed and ten three-toed sloths living at the same site. The fungal communities differed between the species; in this sample, host species explained the differences better than sex, age, or body weight. This is a comparison from one site and a small sample, not proof that fungal species or their interactions with algae are the same everywhere.