What do ticks look like and what varieties exist? - briefly
Ticks are tiny, oval arachnids measuring about 2 mm to 1 cm when unfed and swelling to several centimeters after feeding; they fall into two main families—Ixodidae (hard ticks) and Argasidae (soft ticks). Prominent species include the deer tick (Ixodes scapularis), the American dog tick (Dermacentor variabilis), the lone‑star tick (Amblyomma americanum), and the soft tropical sand tampan (Ornithodoros savignyi).
What do ticks look like and what varieties exist? - in detail
Ticks are arachnids that resemble small, flattened disks. The body consists of two main sections: the anterior capitulum, which houses the mouthparts, and the posterior idiosoma, which contains the legs and internal organs. The capitulum bears a pair of chelicerae for cutting skin and a hypostome equipped with backward‑pointing barbs that anchor the tick while feeding. The idiosoma bears four pairs of legs in the adult stage; larvae have only three pairs. Legs end in clawed tarsi, enabling the animal to grasp hair or vegetation. The dorsum is covered by a hard or soft shield (scutum) depending on the group; in hard ticks the scutum is a rigid plate, while soft ticks possess a flexible cuticle without a distinct shield. Color ranges from reddish‑brown to dark brown or black, often varying with engorgement: an unfed tick measures 2–5 mm, whereas a fully fed adult can expand to 10–30 mm in length and become markedly swollen.
Varieties are classified into three families, each containing several genera and species of medical and veterinary significance:
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Ixodidae (hard ticks)
- Ixodes scapularis – black‑legged tick, vector of Lyme disease in North America.
- Rhipicephalus sanguineus – brown dog tick, cosmopolitan, transmits ehrlichiosis.
- Dermacentor variabilis – American dog tick, carrier of Rocky Mountain spotted fever.
- Amblyomma americanum – lone star tick, associated with ehrlichiosis and α‑gal allergy.
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Argasidae (soft ticks)
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Nuttalliellidae (monotypic family)
- Nuttalliella namaqua – sole species, primitive traits bridging hard and soft ticks, limited to arid regions of southern Africa.
Within each family, life stages differ morphologically: eggs hatch into six‑legged larvae, which molt to eight‑legged nymphs, and finally to adults. Engorgement alters size dramatically, but the basic body plan remains consistent across species. Identification relies on scutum presence, mouthpart length, festoon patterns on the dorsal surface, and the shape of the anal groove. Understanding these physical characteristics and taxonomic groups is essential for accurate diagnosis of tick‑borne diseases and for implementing targeted control measures.