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Tardigrade (Water Bear)Hypsibius exemplaris

Every figure, record and mechanism on the Tardigrade (Water Bear) profile was written from a source, and this is the working table behind it: 54 claims checked word for word against these sources. The left column is what the page says. The right column is the source's own words, copied, not paraphrased; a ... marks a cut and[brackets] an insertion. Open any source and check it yourself.

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Source
01

Gąsiorek et al. 2018

Gąsiorek et al. (2018). An integrative redescription of Hypsibius dujardini (Doyère, 1840), the nominal taxon for Hypsibioidea (Tardigrada: Eutardigrada). Zootaxa.

The page saysbest known from a strain kept in many laboratories throughout the world
The source saysa commercially available strain that is maintained in many laboratories throughout the world
The page saysNot Evaluated
The source saysrepresents, in fact, a new species: H. exemplaris sp. nov.Note: stats.conservationStatus. No reference states a Red List status; this anchors the species name (described 2018) only. GBIF's copy of the Red List returns NOT_EVALUATED (code NE) for Hypsibius exemplaris Gasiorek, Stec, Morek & Michalczyk, 2018, usage key 9800250, checked 2026-09-28.
The page saysA commercially sold strain kept in many laboratories throughout the world was assumed to be Hypsibius dujardini.
The source saysa commercially available strain that is maintained in many laboratories throughout the world, and assumed to represent H. dujardini sensu stricto
The page saysWhen researchers redescribed the real H. dujardini from DNA markers and detailed anatomy in 2018, that lab strain turned out to represent "in fact, a new species": Hypsibius exemplaris
The source sayswe provide the first integrated taxonomic redescription of H. dujardini ... DNA sequences for three nuclear markers ... represents, in fact, a new species: H. exemplaris sp. nov.Note: the redescription was of H. dujardini itself, not of the lab strain; the writer's 'redescription of that strain' reversed it 2018 is the paper's publication year (gasiorek-2018).
The page saysThe strain sold commercially and kept in many labs worldwide had been assumed to be H. dujardini, but a 2018 study that redescribed the real H. dujardini, using DNA markers alongside detailed anatomy, showed the lab strain was a separate species. It was named Hypsibius exemplaris.
The source saysa commercially available strain that is maintained in many laboratories throughout the world, and assumed to represent H. dujardini sensu stricto, represents, in fact, a new species: H. exemplaris sp. nov.Note: 2018 is the paper's publication year (gasiorek-2018).

Source
02

Chavez et al. 2019

Chavez et al. (2019). The tardigrade damage suppressor protein binds to nucleosomes and protects DNA from hydroxyl radicals. eLife.

The page saysEight-legged micro-survivor
The source sayscomprise a head segment in addition to four body segments that each contains two legsNote: four body segments x two legs each = eight legs
The page saysthe wider tardigrade phylum also includes marine species
The source sayssmall invertebrate animals that are found in marine, freshwater, and terrestrial habitats throughout the Earth
The page saysAcross the phylum, tardigrades typically run about 0.1 to 1 millimeter long
The source saysThey are typically about 0.1 to 1 mm in length
The page saysLand-dwelling tardigrades need a thin film of water to stay active.
The source saysTerrestrial tardigrades require a thin film of water to remain active.
The page saysA second defense may sit in the nucleus.
The source saysThese findings suggest that Dsup promotes the survival of tardigrades under diverse conditionsNote: 'may' keeps the source's 'suggest'
The page saysDsup, a damage-suppressor protein first found in R. varieornatus, has a counterpart in H. exemplaris
The source saysDsup was initially not identified in H. exemplaris ( Yoshida et al., 2017 ), but further analysis revealed a Dsup-like protein in this organism
The page saysfirst found in R. varieornatus
The source saysIn R. varieornatus , the study of chromatin-associated factors revealed a tardigrade-specific protein, termed Dsup, for damage suppressor
The page saysIn lab tests that version also binds to nucleosomes in chromatin, the structure DNA is packaged into, and protects DNA from hydroxyl radicals
The source saysa Dsup ortholog from the tardigrade Hypsibius exemplaris similarly binds to nucleosomes and protects DNA from hydroxyl radicals
The page sayshydroxyl radicals, which ionizing radiation generates in cells
The source sayshydroxyl radicals, which are generated in cells by ionizing radiation
The page saysthe structure DNA is packaged into
The source saysDNA, which is packaged into a structure called chromatin
The page saysIts genome has been sequenced
The source saysthe sequencing of the genomes of Ramazzottius varieornatus ( Hashimoto et al., 2016 ) and Hypsibius exemplaris ( Yoshida et al., 2017 )
The page saysIn the dried, dormant state, tardigrades resist heat, cold, vacuum, pressure, radiation and chemical treatments, and they have been found to survive exposure to the vacuum and radiation of outer space.
The source saysIn the anhydrobiotic state, tardigrades are resistant to extreme conditions of heat, cold, vacuum, pressure, radiation, and chemical treatments. Remarkably, they have been found to survive exposure to the vacuum and radiation of outer
The page saysAdd water and the animal can be rehydrated to an active form.
The source saysthey undergo anhydrobiosis into a dormant dehydrated state from which they can be rehydrated to an active form
The page saysTardigrades, also called water bears or moss piglets
The source saysTardigrades, which are also known as water bears or moss piglets
The page sayshave four body segments that each carry two legs
The source saysfour body segments that each contains two legs

Source
03

Yoshida et al. 2017

Yoshida et al. (2017). Comparative genomics of the tardigrades Hypsibius dujardini and Ramazzottius varieornatus. PLOS Biology.

The page saysLimnoterrestrial (freshwater and land), and best known from a strain kept in many laboratories throughout the world
The source saysH . dujardini , a limnoterrestrial tardigrade that can undergo anhydrobiosis only after extensive pre-exposure to drying conditionsNote: Yoshida's 'H. dujardini' is H. exemplaris: chavez-2019 says 'the strain of tardigrades that was designated as Hypsibius dujardini in Yoshida et al. (2017) has since been found to be a new species that is now termed Hypsibius exemplaris'. Lab-strain clause from gasiorek-2018 below. 'Worldwide' was cut: gasiorek-2018 says the wide range belonged to misidentified H. dujardini records, and no source gives H. exemplaris a wild range.
The page saysIn lab culture, the green alga Chlorella vulgaris.
The source saystardigrades were fed Chlorella vulgaris (Chlorella Industry)Note: methods, culture of strain H. dujardini Z151 (= H. exemplaris, see chavez-2019 note). Wild diet unsourced, so 'Herbivorous' was cut.
The page saysUnlike its relative Ramazzottius varieornatus, which tolerates rapid desiccation
The source saysR . varieornatus , a related species with tolerance to rapid desiccation
The page saysH. exemplaris enters that dormant state only "after extensive pre-exposure to drying conditions."
The source sayscan undergo anhydrobiosis only after extensive pre-exposure to drying conditions
The page saysA 2017 genome study dried it slowly, at 85% relative humidity for 48 hours
The source saysplaced in a chamber maintained at 85% RH for 48 h for H . dujardiniNote: 2017 is the paper's publication year; the strain dried is Z151, named H. dujardini there and H. exemplaris since (chavez-2019)
The page sayscounted a batch as successfully dormant when more than 90% of the animals recovered after rehydration
The source saysSuccessful anhydrobiosis was assumed when >90% of the samples prepared in the same chamber recovered after rehydration.Note: a success threshold in the methods, not a measured survival rate; the writer's 'more than 90% of a lab batch survives' overstated it
The page saysLab colonies of H. exemplaris are fed the green alga Chlorella vulgaris.
The source saystardigrades were fed Chlorella vulgaris (Chlorella Industry)

Source
04

Richaud et al. 2020

Richaud et al. (2020). Ultrastructural analysis of the dehydrated tardigrade Hypsibius exemplaris unveils an anhydrobiotic-specific architecture. Scientific Reports.

The page saysDries into a dormant "tun" in which its cells and mitochondria shrink
The source saysreductions in the sizes of both cells and mitochondria were detected in dehydrated animals
The page saysin one lab study active H. exemplaris measured about 164 micrometers
The source sayshydrated tardigrades measured 164 +/− 32 µm, while tuns measured 101 +/− 12 µm
The page saysH. exemplaris contracts into a compact ball called a tun
The source saysThe contraction of the body in the tun was observed
The page saysthe shape tardigrades form to reduce their body surface area and rate of evaporation
The source saystardigrades and rotifers form a tun to reduce their body surface area and rate of evaporation
The page saysIn one study, tuns dried for six days
The source sayswe dehydrated Hypsibius exemplaris for 6 days
The page saystuns dried for six days measured about 101 micrometers
The source saystuns measured 101 +/− 12 µm
The page saysthe cells and mitochondria inside had shrunk too
The source saysreductions in the sizes of both cells and mitochondria were detected in dehydrated animals
The page saysIn one study, active Hypsibius exemplaris measured about 164 micrometers and tuns dried for six days about 101
The source sayswe dehydrated Hypsibius exemplaris for 6 days ... hydrated tardigrades measured 164 +/− 32 µm, while tuns measured 101 +/− 12 µm
The page saysand the cells and mitochondria inside had shrunk too
The source saysreductions in the sizes of both cells and mitochondria were detected in dehydrated animals
The page saysThe researchers read the shrunken mitochondria as a sign that metabolism in a tun is minimal, with limited breathing.
The source sayswe postulate that this decreased cristae size reflects the fact that the metabolism in tuns is minimal with limited breathingNote: the source's 'decreased cristae size' is the inner-membrane folds of the shrunken mitochondria; 'read as a sign' keeps 'postulate'

Source
05

Clark-Hachtel et al. 2024

Clark-Hachtel et al. (2024). The tardigrade Hypsibius exemplaris dramatically upregulates DNA repair pathway genes in response to ionizing radiation. Current Biology.

The page saysmeets a dose of gamma rays by rapidly switching on many of its own DNA-repair genes
The source saysthe tardigrade Hypsibius exemplaris suffers DNA damage upon gamma irradiation, but the damage is repaired ... irradiation induces a rapid upregulation of many DNA repair genes
The page saysanswers gamma-ray damage by rapidly switching on many DNA-repair genes
The source saysirradiation induces a rapid upregulation of many DNA repair genes
The page saysTardigrades can survive doses of ionizing radiation up to about 1,000 times the lethal dose for humans.
The source saysTardigrades can survive remarkable doses of ionizing radiation, up to about 1,000 times the lethal dose for humans.Note: phylum scope, as the source states it; not measured for H. exemplaris in the abstract. Also covers the heading 'Radiation, a Thousand Times Over'.
The page saysH. exemplaris isn't immune: gamma rays still damage its DNA. What's different is the comeback: the damage is repaired.
The source saysthe tardigrade Hypsibius exemplaris suffers DNA damage upon gamma irradiation, but the damage is repaired
The page saysIrradiation rapidly switches on many DNA-repair genes in H. exemplaris, pushing some repair transcripts to among the most abundant in the animal.
The source saysirradiation induces a rapid upregulation of many DNA repair genes ... making some DNA repair transcripts among the most abundant transcripts in the animal
The page saysAt least one of those genes is important to radiation tolerance in the living animal.
The source saysWe show that at least one such gene is important in vivo for tardigrade radiation tolerance.
The page saysAs a group, up to about 1,000 times the dose of ionizing radiation that would kill a person. Hypsibius exemplaris still takes DNA damage from gamma rays.
The source saysTardigrades can survive remarkable doses of ionizing radiation, up to about 1,000 times the lethal dose for humans. ... the tardigrade Hypsibius exemplaris suffers DNA damage upon gamma irradiation, but the damage is repaired
The page saysin lab tests boosting some of its repair genes in bacteria was enough to raise the bacteria's radiation tolerance
The source saysBy expressing tardigrade genes in bacteria, we validate that increased expression of some repair genes can suffice to increase radiation tolerance.
The page saysRadiation, Up to a Thousand Times Over
The source saysup to about 1,000 times the lethal dose for humansNote: heading for the phylum-scope figure the section's first sentence states
The page saysan animal whose DNA is damaged by gamma rays and then repaired
The source saysthe tardigrade Hypsibius exemplaris suffers DNA damage upon gamma irradiation, but the damage is repairedNote: vibe.reason, settled in #913
The page saysit answers gamma-ray damage by rapidly switching on many DNA-repair genes
The source saysirradiation induces a rapid upregulation of many DNA repair genesNote: vibe.reason, settled in #913

Source
06

Malki et al. 2021

Malki et al. (2021). Intrinsically Disordered Tardigrade Proteins Self-Assemble into Fibrous Gels in Response to Environmental Stress. Angewandte Chemie International Edition.

The page saysDisordered proteins found only in tardigrades play an essential role in the shutdown.
The source saystardigrade‐unique intrinsically disordered proteins have been shown to play an essential role in tardigrade anhydrobiosisNote: 'found only in tardigrades' renders the source's 'tardigrade-unique'
The page saysIn the lab, one of this species' proteins, CAHS-8, formed long fibres and finally a gel as it grew more concentrated
The source saysCAHS‐8 from Hypsibius exemplaris ... Upon concentration, the protein is shown to successively form oligomers, long fibres, and finally gels constituted of fibres
The page sayssoluble proteins caught in the gel's cavities kept their functional form
The source saysSoluble proteins can be encapsulated within cavities in the gel, maintaining their functional form.

Source
07

Goldstein 2018

Goldstein (2018). The Emergence of the Tardigrade Hypsibius exemplaris as a Model System. Cold Spring Harbor Protocols.

The page saysThe species has a generation time under two weeks at room temperature, stocks can be frozen and revived, and its body and embryos are optically clear.
The source sayshas a generation time of <2 wk at room temperature. Stocks of animals can be stored frozen and revived. The animals and their embryos are optically clear
The page saysresearchers have built techniques for it that include microinjection and RNA interference
The source saysWe have developed techniques for laboratory study of this system, including methods for microinjection of animals, immunolocalization, in situ hybridization, RNA interference
The page saysA 2018 review describes it as an emerging model system, used to study how animal form evolves and how biological materials survive extreme environments.
The source saysI review the development of this animal as an emerging model system, as well as recent molecular studies aimed at understanding the evolution of developmental mechanisms that underpin the evolution of animal form and at understanding how biological materials can survive extreme environmentsNote: 2018 is the paper's publication year (goldstein-2018).

How the table was made: a writer drafted the profile from these sources and logged each claim with its quote, a reviewer with nothing but this table checked every sentence said no more than its quote, and a script confirmed each quote appears word for word in the source. The method is in the site'sAbout page.