How does a tick that has fed on blood over days appear? - briefly
After several days of feeding, the tick’s body swells markedly, with a distended, gray‑brown abdomen and visible mouthparts at the attachment site. The cuticle looks stretched and the tick may appear sluggish.
How does a tick that has fed on blood over days appear? - in detail
A tick that has remained attached for several days undergoes marked morphological changes that are readily observable. The most conspicuous alteration is the expansion of the abdomen, which can increase in volume up to tenfold. This engorged segment becomes distended, balloon‑like, and visibly filled with blood, giving the tick a markedly rounded silhouette. The dorsal surface changes from a flat, brown or reddish‑brown hue to a darker, often glossy appearance; in many species the cuticle turns a deep mahogany or blackish shade as the underlying hemolymph thickens.
The ventral side shows a pronounced swelling of the capitulum, while the mouthparts (hypostome and palps) remain embedded in the host’s skin. Legs, which are relatively short in unfed stages, appear compressed against the body and may be partially hidden beneath the engorged cuticle. The overall length can increase from 2–3 mm in an unfed nymph to 10–12 mm in a fully engorged adult, depending on species.
Key visual indicators of a multi‑day fed tick include:
- Abdominal enlargement: spherical, blood‑filled, often exceeding the width of the head.
- Color shift: from light tan or gray to deep brown, black, or reddish‑brown.
- Leg positioning: legs tucked close to the body, giving a compact look.
- Surface texture: cuticle stretched, appearing smooth and taut; occasional visible fissures where the cuticle has split to accommodate expansion.
- Mouthpart visibility: hypostome remains anchored, sometimes observable as a small protrusion at the attachment site.
Species‑specific differences persist. Ixodes spp. typically retain a more elongated shape even when engorged, while Dermacentor and Amblyomma species develop a broader, more oval profile. In all cases, the tick’s weight increases dramatically, often reaching 100–200 mg, reflecting the volume of ingested blood.
These characteristics enable rapid identification of a tick that has fed for several days, facilitating appropriate removal and medical assessment.