What does the smallest tick look like? - briefly
The tiniest tick is the larval stage, about 0.5 mm long, translucent to pale orange, and bearing six legs. Its body is oval and lacks the hardened scutum characteristic of adult ticks.
What does the smallest tick look like? - in detail
The tiniest known tick species, «Ornithodoros hermsi», measures approximately 1.5 mm in length when unfed. Its body is oval, slightly flattened dorsoventrally, and covered by a smooth, semi‑transparent cuticle that reveals a pale, off‑white to light tan coloration. The dorsal surface lacks a hard scutum; instead, a thin, flexible integument permits expansion during blood intake.
Key morphological characteristics include:
- Capitulum positioned anteriorly, with a short, rounded gnathosoma bearing three pairs of mouthparts (chelicerae, hypostome, and palps).
- Eight legs, each about 0.25 mm long, bearing short, blunt setae rather than the long hairs seen in larger ixodid ticks.
- Eyes absent; sensory organs are limited to simple pit receptors on the ventral side.
- Fanged hypostome with a single row of backward‑pointing teeth, facilitating rapid attachment to small mammalian hosts.
When engorged, the adult expands to roughly 3 mm, adopting a swollen, balloon‑like appearance. The cuticle stretches, becoming more translucent, and the abdomen may exhibit a faint reddish hue due to the ingested blood. Larvae are even smaller, typically 0.5 mm, and retain a similar oval shape but lack fully developed mouthparts, relying on passive attachment to hosts.
Identification relies on:
1. Size range 0.5–1.5 mm for unfed stages.
2. Absence of a scutum and presence of a smooth dorsal surface.
3. Short, blunt legs with limited setae.
4. Anteriorly placed capitulum with a simple hypostome.
These attributes collectively define the visual appearance of the smallest tick, distinguishing it from larger ixodid and argasid relatives.