---
title: "What the sources say about the Water Flea | AnimalTracks.wiki"
description: "48 claims from the Water Flea profile, each beside the words of the source that backs it."
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canonical: "https://animaltracks.wiki/animals/water-flea/sources/"
---

# What the sources say about the Water Flea (*Daphnia pulex*)

> 48 claims from the Water Flea profile, each beside the words of the source that backs it. A "..." marks a cut in a quote and [brackets] an insertion.

Profile: [Water Flea](https://animaltracks.wiki/animals/water-flea/)

## Daphnia pulex. Animal Diversity Web, University of Michigan.

https://animaldiversity.org/accounts/Daphnia_pulex/

| The page says | The source says |
| :--- | :--- |
| A mostly see-through | most of its outer covering is clear, showing most of the internal organs at work (note: tagline; the account's sentence on D. pulex anatomy) |
| pond crustacean | the highest concentrations of Daphnia populations are found in the vegetation in most lakes and ponds (note: tagline) |
| Almost every permanent, nutrient-rich water body, mostly fresh water | can be found in almost every permanent, eutrophic (nutrient-rich) water body (note: stats.habitat; ADW also says Daphnia are generally freshwater organisms) |
| Phytoplankton and fine detritus filtered from the water | most species of Daphnia, including D. pulex, are herbivorous or detritivorous (feeding on phytoplankton) (note: stats.diet; genus scope in ADW's food-habits paragraph, which also gives the detritus and filtering) |
| Not Evaluated | IUCN Red List [Link] Not Evaluated (note: conservationStatus; ADW lists the IUCN Red List status as Not Evaluated, and GBIF's copy of the Red List has no category for this name (prefetch 2026-10-11). Nothing quoted from an API.) |
| Water fleas as a group are generally 0.2 to 3.0 mm long | They are, in reality, a type of small crustacean and are generally 0.2-3.0 mm long (note: scope: water fleas as a group, as the account words it) |
| Most of its outer covering is clear, showing most of the internal organs at work, including the heart. | most of its outer covering is clear, showing most of the internal organs at work, including the heart |
| They got their name from their general appearance and their jerky swimming, which resemble a land flea's. | Their common name was given because of their general appearance and jerky swimming motions which resembles that of the land flea |
| the most common water flea, a group found in almost every permanent, nutrient-rich water body | Daphnia pulex is the most common species of the water flea, an organism which can be found in almost every permanent, eutrophic (nutrient-rich) water body |
| lists it as native to the Nearctic, Palearctic, Oriental, Ethiopian, Neotropical and Australian regions, biologists' names for land from North America to Australia | nearctic nearctic native native palearctic palearctic native native oriental oriental native native ethiopian ethiopian native native neotropical neotropical native native australian australian native native (note: range list as extracted from the ADW map table; the gloss is geography) |
| Daphnia are filter feeders that do not usually seek out food: their legs keep water moving through the shell, and bristles called setae filter out food particles. | They are filter feeders meaning they do not usually actively seek food; they merely create a constant movement of water using their thoraic legs through their carapace where they are able to filter out any food particles with the setae (note: genus scope) |
| Like most Daphnia, it eats phytoplankton, tiny drifting algae, and detritus, bits of decaying matter. | most species of Daphnia, including D. pulex, are herbivorous or detritivorous (feeding on phytoplankton) |
| Animal Diversity Web puts water fleas at generally 0.2 to 3.0 mm long. | generally 0.2-3.0 mm long (note: FAQ) |

## Colbourne et al. (2011). The Ecoresponsive Genome of Daphnia pulex. Science.

https://doi.org/10.1126/science.1197761

| The page says | The source says |
| :--- | :--- |
| 200-megabase genome holds at least 30,907 genes | which is only 200 megabases and contains at least 30,907 genes (note: tagline) |
| Some clones grow neckteeth in response to chemical cues from the predator Chaoborus | This clone was shown to respond to chemical cues from Chaoborus by producing distinct neckteeth (note: stats.superpower; one D. pulex clone (R9)) |
| is a microcrustacean, a tiny kind of crustacean | the microcrustacean Daphnia pulex |
| is only 200 megabases | which is only 200 megabases |
| Yet it holds at least 30,907 genes. | contains at least 30,907 genes |
| the animal has an elevated rate of gene duplication, which makes tandem gene clusters | The high gene count is a consequence of an elevated rate of gene duplication resulting in tandem gene clusters |
| More than a third of its genes have no detectable match in any other available proteome | More than a third of Daphnia's genes have no detectable homologs in any other available proteome |
| The animal that was sequenced was a natural isolate within the D. pulex species complex. | A natural isolate within the D. pulex species complex was picked for sequencing |
| Daphnia-specific genes, including many loci in stretches otherwise devoid of annotations, were the most responsive genes to ecological challenges. | Daphnia-specific genes, including many additional loci within sequenced regions that are otherwise devoid of annotations, are the most responsive genes to ecological challenges (note: blockquote; the unannotated-loci clause restored) |
| clone from arctic Canada, called R9 | Daphnia pulex clone R9 (isolated from arctic Canada by Dr. Larry Weider) |
| was shown to respond to chemical cues from the predator Chaoborus by producing distinct neckteeth | This clone was shown to respond to chemical cues from Chaoborus by producing distinct neckteeth |
| All juveniles in the induction treatment carried neckteeth. | All juveniles in the induction treatment carried neckteeth. |

## Schurko, Logsdon & Eads (2009). Meiosis genes in Daphnia pulex and the role of parthenogenesis in genome evolution. BMC Evolutionary Biology.

https://doi.org/10.1186/1471-2148-9-78

| The page says | The source says |
| :--- | :--- |
| reproduces by cyclical parthenogenesis, which alternates bouts of clonal and sexual reproduction | The microcrustacean Daphnia pulex reproduces by cyclical parthenogenesis |
| cyclical parthenogenesis, which alternates bouts of clonal and sexual reproduction | cyclical parthenogenesis, which alternates bouts of clonal and sexual reproduction (note: definition, from the paper's intro on animals generally) |
| females make summer eggs that develop right away in the mother's brood chamber, with no fertilization | Direct-developing eggs (also called subitaneous or summer eggs) are produced parthenogenetically and immediately develop in the female's brood chamber prior to hatching (note: 'with no fertilization' glosses parthenogenetically) |
| Females make direct-developing eggs that grow in the brood chamber and hatch without fertilization. | Direct-developing eggs (also called subitaneous or summer eggs) are produced parthenogenetically and immediately develop in the female's brood chamber prior to hatching (note: FAQ) |
| The resting eggs made in the sexual cycle do need fertilization, plus a long spell of dormancy. | haploid resting eggs (also called ephippial, diapause, or winter eggs) are produced by meiosis and require fertilization and a period of extended dormancy for development to complete (note: FAQ) |
| Some lineages reproduce by obligate parthenogenesis | genetic and phenotypic evidence has revealed D. pulex lineages that reproduce by obligate parthenogenesis |
| they have lost the requirement for meiosis and fertilization to produce viable resting eggs | obligate parthenogens have lost the requirement for meiosis and fertilization to produce viable resting eggs |
| In its clonal phase a female makes summer eggs with no fertilization | Direct-developing eggs (also called subitaneous or summer eggs) are produced parthenogenetically and immediately develop in the female's brood chamber prior to hatching (note: vibe.reason, same quote as the body) |

## Eads et al. (2007). Profiling sex-biased gene expression during parthenogenetic reproduction in Daphnia pulex. BMC Genomics.

https://doi.org/10.1186/1471-2164-8-464

| The page says | The source says |
| :--- | :--- |
| Crowding, lower temperatures or a food shortage can switch the program. | such as crowding, lowered temperature or food scarcity can induce either male production |
| They can bring on males, which are genetic copies of their mothers | males are genetically identical to their mothers |
| haploid eggs that are fertilized and overwinter in a dormant state called diapause | haploid gametes that are fertilized and overwinter in a state of diapause |
| crowding, cold or a food shortage switches the program | such as crowding, lowered temperature or food scarcity can induce either male production (note: vibe.reason, same quote as the body) |

## Tucker et al. (2013). Population-genomic insights into the evolutionary origin and fate of obligately asexual Daphnia pulex. Proceedings of the National Academy of Sciences.

https://doi.org/10.1073/pnas.1313388110

| The page says | The source says |
| :--- | :--- |
| A genome study of 11 sexual and 11 asexual genotypes indicates that today's asexual lineages are very young. | Whole-genome analysis of 11 sexual and 11 asexual genotypes of Daphnia pulex indicates that current asexual lineages are in fact very young |
| Genes passed in from a sister species, Daphnia pulicaria, underlie the origin of their asexuality | introgression from a sister species, Daphnia pulicaria, underlies the origin of the asexual phenotype (note: introgression glossed as genes passed in) |
| The spread of asexuality is as recent as 1,250 years | indicates that the spread of asexuality is as recent as 1,250 y |
| although the genetic element that suppresses meiosis could be substantially older | although the origin of the meiosis-suppressing element or elements could be substantially older (note: the source's own qualifier on the 1,250-year figure) |

## Leoni & Garibaldi (2009). Population dynamics of Chaoborus flavicans and Daphnia spp.: effects on a zooplankton community in a volcanic eutrophic lake with naturally high metal concentrations (L. Monticchio Grande, Southern Italy). Journal of Limnology.

https://doi.org/10.4081/jlimnol.2009.37

| The page says | The source says |
| :--- | :--- |
| Cues from invertebrate predators are known to induce longer tail spines, bigger helmet crests or neck teeth in Daphnia, a defence that makes the prey harder to handle or better at escaping. | kairomones of invertebrate predators are known to induce elongation of tail spines, enlarged helmet crests or the development of neck teeth in Daphnia spp. (Parejko 1991; Spitze 1992; Black 1993; Repka et al. 1995) as a defence mechanism that makes the handling of prey more difficult (Caramujo & Boavida 2000) and/or increases the prey's escape ability (note: genus scope, stated as such on the page) |

## Ukhueduan et al. (2022). Relationship between oxidative stress and lifespan in Daphnia pulex. Scientific Reports.

https://doi.org/10.1038/s41598-022-06279-4

| The page says | The source says |
| :--- | :--- |
| In a lab study of 11 clones kept under identical conditions, the median lifespan ran from about 15 to about 85 days. | The median lifespans in 11 clones of D. pulex were determined by life tables under identical conditions. As seen in Fig. 1 A, the median lifespans differ greatly (~ 15 to 85 days) among the clones. |
| When one lab raised 11 D. pulex clones under identical conditions, the clones' median lifespans differed greatly, from roughly 15 days to roughly 85. | The median lifespans in 11 clones of D. pulex were determined by life tables under identical conditions. As seen in Fig. 1 A, the median lifespans differ greatly (~ 15 to 85 days) among the clones. (note: FAQ) |
| Lifespan varies by clone. | the median lifespans differ greatly (~ 15 to 85 days) among the clones |
| It depends on the clone. | the median lifespans differ greatly (~ 15 to 85 days) among the clones (note: FAQ) |

## Liu et al. (2019). Polystyrene nanoplastic exposure induces immobilization, reproduction, and stress defense in the freshwater cladoceran Daphnia pulex. Chemosphere.

https://doi.org/10.1016/j.chemosphere.2018.09.176

| The page says | The source says |
| :--- | :--- |
| In a lab study, after exposure to polystyrene nanoplastic, the digestive organs glowed with the particles | the digestive organs of D. pulex were strongly fluorescent after exposure to the nanoplastic particles |
| every treatment group produced fewer offspring per female | total offspring per female and number of clutches were decreased in all the treatment groups |