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What the sources say

Immortal JellyfishTurritopsis dohrnii

Every figure, record and mechanism on the Immortal Jellyfish profile was written from a source, and this is the working table behind it: 41 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

Hasegawa et al. 2022

Hasegawa et al. (2022). Genome assembly and transcriptomic analyses of the repeatedly rejuvenating jellyfish Turritopsis dohrnii. DNA Research.

The page saysUnlike almost all animals, including most jellyfish, some cnidarian species can turn a medusa back into a polyp.
The source saysUnlike almost all multicellular animals, including most jellyfish species, some cnidarian species show life cycle reversion, 1–8 in which mature and young medusae transform directly into an earlier developmental stage namely, the polyp stageNote: footnote numbers inside quote; verify may need ... cut
The page saysAnother 2022 genome paper counted just two species of hydrozoan jellyfish, T. dohrnii and a second, unidentified Turritopsis, that had shown repeated reversal in the laboratory.
The source saysOnly two hydromedusan species, Turritopsis dohrnii and T . sp., have exhibited experimental multiple-repeat life cycle reversion in the laboratoryNote: Hasegawa et al. 2022 (DNA Research). Hydromedusan = hydrozoan jellyfish; T. sp. = unidentified species. Past tense: a count as of 2022; the 2024 Mnemiopsis report is a ctenophore, outside the hydromedusan scope
The page saysThe unidentified one went through as many as 10 reversals in response to severe damage with needles.
The source saysTurritopsis sp. showed as many as 10 repeated cycles of rejuvenation in response to severe mechanical damage with needles.
The page saysThe repeats have been watched in the laboratory.
The source sayshave exhibited experimental multiple-repeat life cycle reversion in the laboratory

Source
02

Pascual-Torner et al. 2022

Pascual-Torner et al. (2022). Comparative genomics of mortal and immortal cnidarians unveils novel keys behind rejuvenation. Proceedings of the National Academy of Sciences.

The page saysA 2022 genome paper calls T. dohrnii immortal because the chance of a sexually mature medusa rejuvenating goes up to 100%, with no apparent limit on the number of cycles for one individual.
The source sayswe define T. dohrnii as “immortal” because the probability of sexually mature medusae to rejuvenate goes up to 100%, with no apparent limit in the number of ontogeny reversal cycles for a given individualNote: 2022 is the reference's year field (Pascual-Torner 2022)
The page saysA medusa that is hurt, starved or old can switch back to a polyp, and a 2022 genome study reports no apparent limit to how many times one individual can do it.
The source sayswith no apparent limit in the number of ontogeny reversal cycles for a given individualNote: 2022 is the reference's year field (Pascual-Torner 2022)

Source
03

Matsumoto, Piraino & Miglietta 2019

Matsumoto, Piraino & Miglietta (2019). Transcriptome Characterization of Reverse Development in Turritopsis dohrnii (Hydrozoa, Cnidaria). G3 Genes|Genomes|Genetics.

The page saysthat can turn back into a polyp instead of dying, in the lab at least
The source saysMedusae of Turritopsis dohrnii undergo reverse development in response to physical damage, adverse environmental conditions, or aging.Note: tagline; 'in the lab at least' hedges: the repeats were seen in the laboratory (hasegawa-2022 claim below)
The page saysLife cycle reversal: a damaged, starved or aging medusa becomes a cyst, then a polyp
The source saysSenescent, weakened or damaged medusae transform into a cluster of poorly differentiated cells (known as the cyst stage), which metamorphose back into a preceding life cycle stage, the polyp.Note: stats.superpower; starved is NEMESIS (claim below)
The page saysA senescent (old), weakened or damaged medusa can transform into a cluster of poorly differentiated cells called the cyst stage, and the cyst then metamorphoses back into a polyp.
The source saysSenescent, weakened or damaged medusae transform into a cluster of poorly differentiated cells (known as the cyst stage), which metamorphose back into a preceding life cycle stage, the polyp.
The page saysA 2019 study compared the three stages and found DNA repair genes more active in the cyst than in the polyp or the medusa.
The source saysin the Cyst stage, the category ‘DNA repair (GO:0006281)’ was also found to be over-expressed in all three comparative analysesNote: 2019 is the reference's year field; the three analyses were Cyst vs Polyp, Cyst vs Medusa, Cyst vs Polyp+Medusa; polyps and medusae came from Otranto, Italy and cysts from Bocas del Toro, Panama, so no place is named
The page saysThe authors say that may be part of how the reset works.
The source saysBiological processes that occur at the cyst stage such as telomerase activity, regulation of transposable elements and DNA repair systems, and suppression of cell signaling pathways, mitotic cell division and cellular differentiation and development may be involved in T. dohrnii ’s reverse development and transdifferentiation.
The page saysThe medusa shrinks, stops swimming and settles onto the bottom.
The source saysDuring its reverse development, medusae shrink and lose their swimming competence, settle onto the substrate
The page saysIt turns into a cyst-like stage with a thin outer envelope and no features you could call medusa or polyp.
The source saystransform into a cyst-like stage characterized by a thin chitinous external envelope with no recognizable morphological features that can be ascribed to either medusa or polyp
The page saysOver the next 24 to 36 hours it develops polyp features, including the structure new polyps arise from.
The source saysIn the following 24-36 hr, the cyst develops polyp-typical features, such as the stolonal hydrorhiza, where new polyps will arise from
The page saysThe switch involves transdifferentiation, in which specialised cells are reprogrammed into other cell types.
The source saysthe ontogeny reversal of T. dohrnii involves cell transdifferentiation, a reprogramming of structural and functional commitment and gene expression of well-differentiated, somatic cells into other cell typesNote: well-differentiated = specialised
The page saysa medusa that, when old, damaged or starved, can turn into a cyst of poorly differentiated cells and then back into a polyp
The source saysSenescent, weakened or damaged medusae transform into a cluster of poorly differentiated cells (known as the cyst stage), which metamorphose back into a preceding life cycle stage, the polyp.Note: vibe.reason, task #969

Source
04

Miglietta & Lessios 2008

Miglietta & Lessios (2008). A silent invasion. Biological Invasions.

The page saysA genetic study found the same species in Florida, Panama and Japan as in Spain and Italy
The source saysa clade of the mitochondrial 16S gene in Turritopsis which contains individuals collected from Japan, the Pacific and Atlantic coasts of Panama, Florida, Spain, and Italy
The page saysand called it a human-mediated introduction.
The source saysHere we identify a human mediated, worldwide introduction of the hydrozoan species Turritopsis dohrnii.
The page saysIts authors say Turritopsis medusae that revert when starved or damaged can easily survive long trips in cargo ships and ballast water.
The source saysMedusae of Turritopsis, however, when starved or damaged, are able to revert their life cycle, going back to the polyp stage through a process called transdifferentiation. They can thus easily survive through long journeys in cargo ships and ballast waters.

Source
05

NEMESIS, Smithsonian Environmental Research Center

Turritopsis dohrnii. NEMESIS, Smithsonian Environmental Research Center.

The page saysA bell up to 3.3 millimetres wide
The source saysThe adult medusae are up to 2.7 mm in height and 3.3 mm in diameter, with 14-32 tentacles.
The page saysRocks, docks and hulls as a polyp
The source saysThe hydroid stage of this species can be found attached to rocks, docks, pilings and ships' hulls.Note: stats.habitat; hydroid = polyp stage
The page saysopen water as a medusa
The source saysThe colonies grow medusa buds which release planktonic medusae.Note: stats.habitat
The page saysthe Western Mediterranean and Adriatic, plus introduced populations in Florida, Panama and Japan
The source saysis a common hydroid on rocky substrates in the Western Mediterranean and Adriatic ... Introduced populations are known from the Indian River Lagoon, Florida; both the Caribbean and Pacific coasts of Panama; and Japan.Note: stats.habitat
The page saysZooplankton
The source saysFood: ZooplanktonNote: stats.diet; GBIF has no IUCN category for this name (prefetch: no assessment), so conservationStatus stays Not Evaluated; no status claim on the page
The page saysThe polyp is a branching colony that sticks to rocks, docks, pilings and ships' hulls.
The source saysThe hydroid stage of this species can be found attached to rocks, docks, pilings and ships' hulls.
The page saysThe colony buds off medusae, the jellyfish form, which drift as plankton.
The source saysThe colonies grow medusa buds which release planktonic medusae.
The page saysAn adult medusa is up to 2.7 millimetres tall and 3.3 millimetres wide
The source saysThe adult medusae are up to 2.7 mm in height and 3.3 mm in diameter, with 14-32 tentacles.
The page saysThe species eats zooplankton
The source saysFood: Zooplankton
The page saysIt was first described from Naples, Italy, and its polyps are common on rocks in the Western Mediterranean and the Adriatic.
The source saysIt was first described from Naples, Italy, and is a common hydroid on rocky substrates in the Western Mediterranean and AdriaticNote: hydroid = polyp; rocky substrates = rocks
The page saysStarved medusae do the same, and a Smithsonian species database says the restart makes each individual "potentially immortal."
The source saysstarved medusae can settle to become an undifferentiated cyst, which grows into a new polyp, restartimg the life cycle. This process of transdifferentiation makes each individual organism potentially immortal
The page saysMedusae in this genus have been widely labelled T. nutricula around the world, and its look-alike species can only be identified by DNA.
The source saysMedusae of the genus Turritopsis have been widely identified as T. nutricula McCrady, 1857 (described from Charleston, South Carolina) around the world ... Identification of the cryptic species of Turritopsis is only possible by molecular meansNote: cryptic species = look-alike species; molecular means = DNA (paraphrase)
The page saysThe reversal restarts the life cycle, which researchers say makes each individual potentially immortal.
The source saysThis process of transdifferentiation restarts the life cycle, and makes each individual organism potentially immortal
The page saysthe polyp colonies grow up to 35 millimetres high.
The source saysmuch-branched, multiple-stemmed colonies up to 35 mm high
The page saysNewly released medusae carry 8 to 12 tentacles, and adults carry 14 to 32
The source saysNewly released medusae have 8-12 tentacles, and a conical manubrium ... The adult medusae are up to 2.7 mm in height and 3.3 mm in diameter, with 14-32 tentacles.Note: tentacle counts are not hedged; 'up to' in the quote belongs to the size sentence
The page says8 in Bocas del Toro, Panama, 12 to 24 in Italy and 14 to 24 in Japan
The source saysNumbers of tentacles in adult medusae vary regionally with: 8 in Bocas del Toro, Panama; 12-24 in Italy; and 14-24 in Japan
The page saysTurritopsis dohrnii is the one the press christened the "immortal jellyfish."
The source saysTurritopsis dohrnii has been christened 'Immortal Jellyfish' in the popular press
The page saysIt has two body forms.
The source saysTurritopsis dohrnii is a hydrozoan with both a polyp and medusa stage.
The page saysMedusae have separate sexes. Their eggs and sperm join to make larvae called planulae, which settle and grow into new polyps.
The source saysThe medusae have separate sexes, and release gametes which fuse to form planulae, which settle to form hydroids.Note: gametes = eggs and sperm; hydroids = polyps; 'larvae' is the definition of planula
The page saysAdult medusae measure up to 3.3 millimetres across
The source saysThe adult medusae are up to 2.7 mm in height and 3.3 mm in diameterNote: faq 3
The page saysstarved
The source saysstarved medusae can settle to become an undifferentiated cyst, which grows into a new polypNote: vibe.reason, task #969
The page saysthe stage medusae bud from
The source saysThe colonies grow medusa buds which release planktonic medusae.Note: vibe.reason, task #969

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.