Ixodida
Enable an AI agent to recognise a tick within Ixodida, assess its developmental and feeding state, and select justified identification, handling or exposure-response actions.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
Researched by: Codex + Grok
Purpose and description
Enable an AI agent to recognise a tick within Ixodida, assess its developmental and feeding state, and select justified identification, handling or exposure-response actions.
Ixodida is the order of obligately blood-feeding parasitiform mites (ticks) diagnosed by a toothed, eversible hypostome used to anchor in vertebrate skin and by Haller's organ on tarsus I, and currently comprising the extant families Ixodidae, Argasidae and Nuttalliellidae.
It can be Compare documented anatomy with an applicable tick identification key and retain the narrowest supported determination.; Record repeated observations of attachment, feeding, detachment and development without filling gaps with assumed transitions.; Route an attached-tick observation to an appropriate human or veterinary removal and exposure-response protocol.; Collect, contain, label and preserve a specimen according to its intended identification or testing use.; Request expert identification or justified laboratory examination when existing evidence cannot support a decision.; Link specimen findings to host-exposure and surveillance records while preserving their different evidential limits..
Distinguishing features
Against other mites, seek the combination of a toothed hypostome and Haller's organ on the first pair of legs using suitable magnification; document whether these structures are actually visible. [Ectoparasite identification guidance](https://www.rcpath.org/static/2a85a3a1-abdc-4a44-926b66b13c0432ea/UK-SMI-B-61i21-Investigation-of-specimens-for-ectoparasites-October-2018.pdf)
Against insects such as fleas or lice, examine body organisation and appendages together: tick larvae have six legs, whereas nymphs and adults have eight, so six legs alone cannot exclude a tick. [CDC tick identification](https://www.cdc.gov/dpdx/ticks/index.html)
Against the narrower category Ixodidae, assess the dorsal scutum and mouthpart position: Ixodida must accommodate soft ticks as well as hard ticks, with characters interpreted for the observed stage. [CDC tick identification](https://www.cdc.gov/dpdx/ticks/index.html)
Against a scab, seed or detached skin fragment, establish organised arthropod anatomy through visible jointed appendages and mouthparts; apparent attachment or movement alone is insufficient.
Scope
+ Identification as Ixodida and evidence supporting finer taxonomic assignments.
+ Tick morphology interpreted against life stage, damage and engorgement.
+ Developmental, feeding, reproductive and viability states.
+ Observed attachment to hosts and occurrence in off-host microhabitats.
+ Specimen-level pathogen evidence and its limits.
+ Tick collection, containment, preservation and referral decisions.
- Diagnosis and treatment of disease in a bitten human or animal.
- The independent biology and classification of pathogens detected in ticks.
- Complete models of host organisms and their immune responses.
- Area-wide infestation estimates and surveillance programme design.
- Pesticide product specifications, dosing and regulatory authorisations.
Characteristics
- Taxonomic determination
- Ixodida unresolved; family, genus or species with identification authority, method and confidence Controls which identification characters and biological expectations may be applied.
- Developmental stage
- egg; larva; nymph with instar if established; adult; unresolved Prevents stage-dependent anatomy and behaviour from being misread as identification errors.
- Sex determination
- female; male; unresolved; not determinable at recorded stage Supports interpretation of adult morphology and reproductive potential without forcing assignments.
- Diagnostic morphology
- Observed states of scutum, capitulum, hypostome, first-leg sensory structures and key-specific characters; not visible; damaged Makes identification reviewable and distinguishes absent structures from unobserved ones.
- Body dimensions
- Length and width in mm with measurement landmarks, stage and feeding state Supports comparison without treating engorgement-related size changes as species differences.
- Feeding condition
- apparently unfed; feeding; partially engorged; fully engorged; indeterminate Informs state assessment while keeping visual feeding estimates distinct from elapsed attachment time.
- Host association
- Host identity and body site; crawling on host; attached; detached from host; association uncertain Separates a host encounter from demonstrated attachment or feeding.
- Attachment interval
- Observed or bounded start and end times; duration in hours; estimation method; unknown Preserves exposure evidence without converting an uncertain encounter into an exact duration.
- Off-host occurrence
- Location, date, substrate or microhabitat, collection method and possible transport history Supports ecological interpretation without assuming the collection location is the place of origin.
- Viability and integrity
- alive; dead; uncertain; intact; damaged; preserved, with observed evidence Determines containment needs and which identification or laboratory methods remain feasible.
- Pathogen examination
- Linked assay, target, specimen or pool, result, date and laboratory interpretation; not tested Keeps laboratory detection separate from demonstrated transmission or disease in a host.
Where this came from
wikidata · CC0 1.0
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 6 bundles · 11 layers · 18 findings · 28 questions.
Tick identity Establish whether the observed organism is a tick and how precisely it can be identified.
Misidentification or confusion between Ixodida and Ixodidae changes which biological and exposure assumptions are justified.
Ixodida recognition
Assess anatomical evidence for membership in the registered group.
Tick character evidence
Record visible diagnostic structures, competing identifications and limits imposed by image quality, stage or damage.
- Which observed structures support Ixodida rather than another mite, an insect or non-animal material? definition
- Which diagnostic structures were examined but unresolved, and which were not examined? measurement
Taxonomic resolution
Constrain family, genus and species assignments to the evidence available.
Supported determination
Retain the identification method, authority, alternative determinations and the applicability of the key to this stage and locality.
- What is the narrowest taxon supported by the observed characters or molecular evidence? boundary
- Which key, reference sequence or expert determination supports that assignment, and does it cover this specimen? provenance
Development and condition Represent stage, viability and transitions without imposing one species' life history on all ticks.
Tick anatomy and feasible next actions depend on development, feeding history and specimen condition.
Stage and integrity
Interpret the specimen's current anatomy and condition.
Stage-aware assessment
Assess developmental stage, adult sex where determinable, viability and damage as separate observations.
- Which anatomical observations establish the stage and, where applicable, adult sex? definition
- What evidence establishes viability, and what damage or preservation limits further assessment? measurement
Developmental transitions
Track observed moulting, maturation and reproductive events.
Observed life history
Separate witnessed transitions from taxon-based expectations; tick life cycles include egg, larval, nymphal and adult stages. [CDC tick lifecycles](https://www.cdc.gov/ticks/about/tick-lifecycles.html)
- Which moults, feeding episodes or egg-laying events were directly observed, and when? provenance
- What taxon-specific evidence supports the expected next transition or number of remaining instars? boundary
Host contact and feeding Describe the tick's relationship to a host and the evidence for a blood meal.
Finding a tick on a host, observing attachment and estimating feeding progress support different decisions.
Attachment evidence
Establish the host contact event and its temporal bounds.
Documented host contact
Record host identity, body site, attachment evidence and observed or uncertain timing.
- Was the tick crawling, attached by its mouthparts or already detached, and on which host and body site? measurement
- Which observations bound attachment duration, and which parts of that interval remain unknown? provenance
Blood-meal state
Interpret engorgement and feeding history using stage-appropriate evidence.
Feeding progress
Record feeding observations and engorgement measures without treating body size as an exact clock.
- Which observations or measurements support the recorded engorgement state? measurement
- Is any proposed feeding-duration estimate validated for this taxon, stage and measurement method? boundary
Off-host context Represent where and how a tick was encountered outside a demonstrated feeding event.
Microhabitat, collection method and transport history affect interpretation of host-seeking activity and local occurrence.
Encounter microhabitat
Locate the organism in its immediate environmental and sampling context.
Collection context
Record substrate, shelter or vegetation, environmental observations and the method that produced the encounter.
- Where and when was the tick found, on what substrate, and by which collection method? provenance
- Was host-seeking, sheltering or another behaviour observed directly, or inferred from the collection setting? boundary
Origin and persistence
Distinguish the collection location from supported conclusions about origin or establishment.
Local occurrence interpretation
Link possible transport on hosts or materials and corroborating encounters without making one specimen prove a resident population.
- Could recent host travel or movement of bedding, equipment or other materials explain this occurrence? provenance
- What additional evidence would be needed to infer local reproduction or persistent infestation? boundary
Examination and response Connect identification and exposure evidence to appropriate specimen handling and referral.
The agent must preserve useful evidence and distinguish tick findings from conclusions about a host's health.
Pathogen evidence
Represent assay findings and the limits of their interpretation.
Detection versus transmission
Separate pathogen detection from vector competence and demonstrated host transmission. [CDC-hosted review of vector competence](https://stacks.cdc.gov/view/cdc/86404)
- Was the result obtained from this individual tick or a pool, using which assay and target? provenance
- What does the evidence establish about detection, and what remains unestablished about viable infection or transmission? boundary
Specimen and exposure routing
Select the next action according to attachment status, evidence needs and available expertise.
Justified next action
Record the intended examination, applicable handling protocol, containment requirements and any host-care referral.
- Which collection, containment or preservation method is compatible with the intended morphological or laboratory examination? action
- Does the observed attachment or host exposure require routing to a human or veterinary response protocol, and which applicable protocol governs that action? action
Evidence and external alignment What the world already says about this thing, gathered so the model can be checked against it.
A model that cannot be lined up against existing standards, identifiers and practice cannot be adopted by anyone who already uses them.
Reported evidence
Findings from the breadth pass, kept separate from the structural claims.
Kinds and varieties
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Ixodidae (hard ticks): scutate ticks with a dorsal shield and a capitulum visible from above; typically one long blood meal per stage
- Argasidae (soft ticks): leathery, non-scutate ticks with a ventral capitulum; typically brief, repeated feeds and nidicolous habits
- Nuttalliellidae: the monotypic living family Nuttalliella namaqua, morphologically intermediate between hard and soft ticks
- Prostriata: hard ticks with an anal groove anterior to the anus (Ixodes and close allies)
- Metastriata: remaining hard-tick genera, with the anal groove posterior to the anus or indistinct
- One-host ticks: all parasitic stages completed on a single individual (e.g. cattle ticks in Rhipicephalus (Boophilus))
- Two- and three-host ticks: one or more stages drop off the host to moult before seeking a new host (the majority of ixodids)
- Fossil Ixodida: Cretaceous amber lineages such as Deinocrotonidae and Khimairidae, treated as distinct families in palaeoacarology
- Which of these kinds and varieties hold for the sense of Ixodida this model covers, and on what evidence? provenance
Identifiers and schemes
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- NCBI Taxonomy - 6939 - txid for order Ixodida
- Wikidata - Q4883548 - Wikidata item for Ixodida
- ICZN scientific name - Ixodida Leach, 1815 - Zoological order-group name; some catalogues instead rank the same taxa as superfamily Ixodoidea
- Which of these identifiers and schemes hold for the sense of Ixodida this model covers, and on what evidence? provenance
Standards and regulation
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- International Code of Zoological Nomenclature (ICZN) - governs formation and priority of tick scientific names
- WOAH (World Organisation for Animal Health) Terrestrial Animal Health Code and Manual - international standards for several tick-borne animal diseases (theileriosis, babesiosis, heartwater, equine piroplasmosis) and for tick control/surveillance
- WHO guidance on tick-borne human diseases (tick-borne encephalitis, Crimean-Congo haemorrhagic fever, Lyme borreliosis) and vector surveillance
- USDA APHIS cattle-fever-tick eradication and quarantine rules for Rhipicephalus (Boophilus) microplus and R. annulatus in the United States
- EU Animal Health Law (Regulation (EU) 2016/429) and listed-disease rules that treat several tick-borne infections as notifiable
- Which of these standards and regulation hold for the sense of Ixodida this model covers, and on what evidence? provenance
Real-world use
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Encountered as ectoparasites of mammals, birds, reptiles and (rarely) amphibians in vegetation, burrows, nests, livestock yards and human dwellings
- Primary medical and veterinary vectors of Lyme borreliosis, rickettsioses, anaplasmosis, ehrlichiosis, babesiosis, theileriosis, tick-borne encephalitis, Crimean-Congo haemorrhagic fever, and (via Ornithodoros) African swine fever virus
- Collected in public-health and livestock programmes by flagging/dragging vegetation, CO2 traps, examination of hosts, and abattoir or quarantine inspection
- Used as experimental animals in acaricide efficacy tests, pathogen-transmission studies, and anti-tick vaccine research (e.g. Bm86 against cattle tick)
- Identified in clinical practice from attached specimens to assign regional disease risk after a bite
- Which of these real-world use hold for the sense of Ixodida this model covers, and on what evidence? provenance
Typical measurements
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Unfed adult body length - 2-7 - mm
- Fully engorged female body length - 8-20 - mm
- Ixodid feeding duration per stage - 2-14 - days
- Argasid feeding duration per meal - 15-120 - minutes
- Eggs laid by a typical ixodid female (single gonotrophic cycle) - 1000-8000 - eggs
- Active legs (larva vs nymph/adult) - 6 (larva), 8 (nymph and adult) - count
- Which of these typical measurements hold for the sense of Ixodida this model covers, and on what evidence? provenance
Failure modes and hazards
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Transmission of bacterial, protozoal and viral pathogens during the blood meal
- Tick paralysis from salivary neurotoxins (notably some Ixodes and Dermacentor species)
- Alpha-gal syndrome (delayed red-meat allergy) after bites of certain hard ticks
- Anaemia, hide damage and production loss from heavy livestock infestation
- Secondary bacterial infection or granuloma at the attachment site, including risk from mouthpart retention if the tick is removed improperly
- Acaricide resistance, especially in one-host cattle ticks, causing control failure
- Misidentification of species or life stage, which assigns the wrong endemic-disease risk to a bite or a locality
- Geographic range expansion with trade and climate (e.g. Hyalomma in Europe; cattle-fever tick reinfestation)
- Which of these failure modes and hazards hold for the sense of Ixodida this model covers, and on what evidence? provenance
Regional variation
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Europe treats Ixodes ricinus as the default woodland tick and TBEV/Lyme as the main human-health frame; North America splits blacklegged tick (I. scapularis, often still called 'deer tick') from western I. pacificus and from American dog tick (Dermacentor variabilis)
- Australia emphasises the paralysis tick Ixodes holocyclus and biosecurity around cattle tick; southern Africa emphasises Amblyomma (heartwater), Rhipicephalus appendiculatus (East Coast fever) and the Ornithodoros moubata complex
- Arid and nest/burrow habitats give argasid (soft) ticks a much larger practical role than in temperate forests, including tick-borne relapsing fever and pig-housing Ornithodoros
- Catalogues disagree on rank and names: many acarologists use order Ixodida; some databases list the same taxa as superfamily Ixodoidea. Argasid generic limits (Ornithodoros versus Carios and related names) remain contested
- Vernacular names differ (English tick, French tique, German Zecke, Spanish garrapata, Turkish kene) and informal names such as 'seed tick' (larva) or 'wood tick' are region-specific and not taxonomic
- Which of these regional variation hold for the sense of Ixodida this model covers, and on what evidence? provenance
Neighbouring kinds and how to tell them apart
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Mesostigmatic haematophagous mites (e.g. Dermanyssus, Ornithonyssus) - Lack a toothed hypostome and Haller's organ; generally much smaller; spiracles in a different position (mesostigmata versus tick stigmatal plates)
- Trombiculid chiggers - Only the six-legged larva is parasitic; they feed via a stylostome rather than an inserted toothed hypostome and lack Haller's organ
- Bed bugs (Cimex) - Insects with six legs in all stages, no hypostome or scutum, and a piercing-sucking beak; they do not remain attached for days
- Sucking lice - Insects with tarsal claws adapted to hair, no Haller's organ, and a true insect head; highly host-specific and permanently ectoparasitic
- Spiders - Free-living arachnids with a constricted waist (except some forms), fang-like chelicerae rather than a toothed hypostome, and no blood-feeding ectoparasitic life cycle
- Hard tick versus soft tick (within Ixodida) - Hard ticks show a dorsal scutum and a capitulum visible from above; soft ticks have a leathery, often mammillated integument and a capitulum hidden ventrally in the nymph and adult
- Which of these neighbouring kinds and how to tell them apart hold for the sense of Ixodida this model covers, and on what evidence? provenance
Sources
- Biology of Ticks, Volumes 1-2 (2nd edition) - Order-level diagnosis (hypostome, Haller's organ), family split, life cycles, feeding duration, medical and veterinary roles, and measurements of size and reproduction
- The Hard Ticks of the World (Acari: Ixodida: Ixodidae) - Circumscription of Ixodidae within Ixodida, prostriate versus metastriate division, valid names, and geographic faunas
- The Argasidae, Ixodidae and Nuttalliellidae (Acari: Ixodida): a world list of valid tick names - The three-family classification of extant Ixodida and the authoritative list of valid tick names used in acarology
- NCBI Taxonomy Browser: Ixodida (txid6939) - The NCBI taxonomic identifier and placement of Ixodida among parasitiform mites
What the second pass must settle
- Which current taxonomic authority should govern Ixodida membership, including Nuttalliellidae, and how should conflicting classifications be retained?
- Which identification keys adequately cover immature, damaged and engorged ticks across the intended geographic coverage?
- Which stage- and taxon-specific exceptions to feeding, nymphal development and reproduction require explicit representation?
- For which taxa and stages are engorgement-based attachment estimates validated, and how should their uncertainty be expressed?
- Which jurisdictional and laboratory protocols should govern attached-tick response, specimen preservation and pathogen-testing interpretation?