What does a water tick look like?

What does a water tick look like? - briefly

A water tick is a tiny, elongated arachnid roughly 2–4 mm long, featuring a dark, glossy, oval body with short legs that cling closely to the torso. Its underside displays a pair of pale, crescent‑shaped markings near the mouthparts.

What does a water tick look like? - in detail

Water ticks are small arachnids, typically measuring 2–5 mm in length when unfed. Their bodies consist of two main regions: a rounded, shield‑like capitulum (the front part containing the mouthparts) and a broader, oval idiosoma (the posterior segment). The capitulum bears a pair of chelicerae and a set of palps, each equipped with fine sensory hairs.

The dorsal surface of the idiosoma is covered by a smooth, semi‑transparent cuticle that may appear pale amber to light brown, depending on species and age. In engorged individuals, the cuticle expands dramatically, becoming balloon‑shaped and taking on a glossy, bluish‑green hue due to the blood meal. Ventral plates are slightly darker, often with a matte finish.

Key morphological details include:

  • Six legs, each ending in a small claw; legs are relatively short, giving the tick a compact silhouette.
  • Two pairs of eyes located near the front of the capitulum, each composed of simple ocelli.
  • A pair of spiracles on the posterior margin of the idiosoma, visible as tiny circular openings.
  • Scutal plates that may display faint ridges or punctate patterns, useful for species identification.
  • A flexible gnathosoma that can be retracted into the body when the tick is not feeding.

When attached to a host, the tick’s mouthparts penetrate the skin, forming a secure attachment. The feeding apparatus consists of a barbed hypostome, which can be seen as a dark, needle‑like structure protruding from the capitulum. Engorgement causes the abdomen to swell up to ten times its original size, altering the overall silhouette from a compact oval to a markedly distended, almost spherical form.

These characteristics, combined with coloration changes during blood intake, allow reliable visual identification of water ticks in both field and laboratory settings.