Daphnia magna
Daphnia magna
Daphnia magna is presented at species resolution, with explicit limits on what can be inferred from appearance alone. It occurs in freshwater, brackish water contexts and may act as grazer, live food. The card separates biological identity, observation, ecological role and aquarium meaning from clinical diagnosis, so a visual resemblance never becomes automatic proof of cause, risk or treatment.
Water type
Freshwater / Brackish
Biological group
Branchiopoda
Record type
Species
Recognition confidence
Medium
Ecological functions
Grazer, Live food
Aquarium impact
Beneficial
Culture and management
Dedicated starter culture
Typical size
2,000 µm – 5,000 µm
Visible to the naked eye
Yes, as an individual
Useful starting magnification
10× to begin observation
Identity, habitat, and ecological role
Identity and taxonomic resolution: Daphnia magna is treated at species level. The accepted name, synonyms and biological group are search aids, not permission to identify an unknown sample from color alone. A defensible identification combines sample origin, intact diagnostic characters, life stage and, where morphology overlaps, validated laboratory methods. The confidence label describes the resolution supported by the evidence and must not be silently promoted to species certainty.
Morphology and dimensions: The relevant form must be observed with a scale and without excessive compression or deterioration. Size, movement, attachment, cellular organization and reproductive structures can narrow the possibilities, but each varies with stage and preparation. Similar-looking debris, biofilm members or unrelated organisms remain part of the differential. Photographs should preserve magnification, orientation and the exact structure measured so another observer can evaluate the same evidence.
Habitat and microhabitat: Documented aquatic scope is freshwater, brackish water. Water column, substrate pores, filter media, plant surfaces and host tissue are different microhabitats even inside one aquarium. Flow, oxygen, light, organic load, salinity and host condition select different populations. A record from one location therefore cannot be generalized to the whole tank, and populations from different salinity regimes are not automatically interchangeable.
Role in the food web: The ecological roles recorded here are grazer, live food. Their actual expression depends on abundance, resources, stage and interactions with bacteria, protists, grazers, predators or hosts. Presence may be beneficial, neutral, contextual or harmful without changing the organism's taxonomy. Clinical relevance requires compatible signs and confirmation; an environmental detection alone does not establish infection or causal responsibility.
Observation, culture, and ecological relationships
Where to look and how to sample: Sample the exact water, surface, sediment or host site where the observation occurred and record date, aquarium, location, volume or area, recent changes and water parameters. Use separate clean tools and preserve an uncontaminated comparison when possible. A concentrated net sample, scrape and free-water drop select different fractions, so the method must travel with the result and absence must not be claimed for organisms the method could not retain.
How to observe and identify: Begin with live behavior and low magnification, then move to the magnification and preparation needed for the discriminating character. Compare several fields, stages and look-alikes rather than one striking image. Microscopy can orient identification, while histology, culture, staining, molecular assays or professional examination may be required for a causal diagnosis. Stop at genus, group or functional level whenever the available character does not support a more precise name.
Presence and meaning in the aquarium: Read the finding together with its abundance, trend, location, animal behavior and ammonia, nitrite, temperature, pH and oxygenation. A stable low-density population may be normal whereas a sudden bloom may indicate newly available resources or system instability. The same visual phenomenon can have several causes, so safe immediate husbandry and documentation come before aggressive control or medication.
Culture, maintenance or use: Management concerns the microhabitat and contamination controls; parameters from one strain are not universal culture limits. Never transfer unknown material between aquariums, aerosolize it or expose wounds and mucosa. Dedicated tools, backups and disposal appropriate to the biological risk prevent an observation exercise from becoming a route of spread.
Documented ecological relationships: Each cross-link distinguishes causative agent, contributor, look-alike, indicator and ecological context, and carries an explicit confidence. These relations describe evidence and direction: who consumes, colonizes, transforms or resembles whom. They are not stocking recommendations. A contributor can be common without being sufficient, and a look-alike warning exists precisely because visual similarity is not a diagnosis.
Risks, biosecurity and limits: Do not infer species, contagion or therapy from a photograph alone. Protect people and animals by isolating suspect hosts when appropriate, using gloves over broken skin, disinfecting dedicated tools and consulting an aquatic veterinarian or qualified laboratory for progressive disease or mortality. Scientific names are retained only at the supported resolution, and uncertain or syndrome-level associations remain explicitly conditional.
Geographic Origin and Distribution
Origin
North America
Identification and observation data
- Record type
- Species
- Il nome scientifico indica una specie precisa. Per usarlo su un organismo trovato in vasca devono però coincidere i caratteri diagnostici, non soltanto il colore o la forma generale. Specie precisa del genere Daphnia; non va usata come sinonimo di tutte le 'pulci d'acqua'.
- Recognition confidence
- Medium
- L'aspetto consente di orientarsi verso il gruppo indicato, ma per arrivare alla specie o al ceppo servono caratteri più fini, preparazioni specifiche o analisi molecolari. Valore nutritivo e taglia dipendono da dieta, clone e stadio. Non trasferire organismi selvatici senza biosecurity.
- Biological group
- Branchiopoda
- Dal punto di vista biologico appartiene a Branchiopoda; per comprenderne il ruolo viene osservato nel contesto di zooplancton e alimento vivo. Per lo zooplancton vanno distinti adulto, stadio larvale, uovo di resistenza e coltura commerciale: possono avere morfologie e funzioni molto diverse. Nomi come copepode o rotifero sono spesso risoluzioni di gruppo, non identificazioni di specie. È stato documentato in acqua dolce, acqua salmastra, ma popolazioni provenienti da salinità diverse non sono automaticamente intercambiabili.
- Ecological functions
- Grazer, Live food
- Nella rete microscopica può agire come pascolatore microbico, risorsa alimentare viva. Filtra alghe, batteri e detrito, può usare il periphyton ed è preda di pesci e invertebrati. Il ruolo effettivo cambia con stadio, densità, risorse disponibili e identità dell'organismo osservato.
- Aquarium impact
- Beneficial
- Utile come preda viva in acqua dolce, ma non adatta a tutte le bocche o a tutti gli ambienti; può essere consumata rapidamente. Il profilo è generalmente utile al funzionamento del sistema, ma beneficio e intensità dipendono da sede, densità e condizioni.
- Culture and management
- Dedicated starter culture
- Coltivabile separatamente con microalghe o alimenti controllati. Densità troppo alta e scarsa ossigenazione favoriscono collassi. Una coltura starter è possibile con protocolli controllati, contenitori di riserva e verifiche di contaminazione.
- Typical size
- 2,000 µm – 5,000 µm
- Adulti spesso nell'ordine di 2–5 mm, corpo trasparente racchiuso nel carapace e movimento a scatti delle antenne. Le dimensioni più comuni si collocano fra 2000 e 5000 µm; stadio vitale, ceppo e preparazione del campione possono però spostare questo intervallo.
- Visible to the naked eye
- Yes, as an individual
- L'individuo o lo stadio descritto può essere percepito a occhio nudo come punto, filo o corpo mobile; i caratteri che ne confermano l'identità richiedono comunque ingrandimento.
- Useful starting magnification
- 10× to begin observation
- Visibile a occhio; 10–40× mostra cuore, tubo digerente, camera di covata ed epibionti. 10× è un buon punto di partenza per trovare l'organismo o la struttura; l'identificazione può richiedere obiettivi più potenti, preparazioni specifiche o confronto molecolare.
Image gallery
Licensed images linked to the species or, when marked, to the closest representative taxon.
Microworld ecological network
Links based on documented kinship, food webs, biofilms, and ecological functions.
