Where does the tick draw blood? - briefly
A tick penetrates the host’s skin with its hypostome and extracts blood from the surrounding capillaries and small vessels. The fluid is drawn through the feeding tube directly into the tick’s digestive tract.
Where does the tick draw blood? - in detail
Ticks attach to a host by inserting their mouthparts, known as the hypostome, into the skin. The hypostome is a barbed structure that penetrates the epidermis and reaches the dermal layer, where it encounters a dense network of capillaries. Once anchored, the tick secretes a cocktail of enzymes and anticoagulants that dilate local blood vessels and prevent clotting, allowing a continuous flow of blood into the feeding cavity.
During the early attachment phase, the tick creates a small feeding lesion approximately 0.5–1 mm deep. The lesion consists of:
- Epidermal breach: the outermost skin barrier is pierced.
- Dermal penetration: the hypostome reaches the superficial dermis, where capillary loops are abundant.
- Capillary access: the tick’s canaliform salivary sheath surrounds the hypostome, forming a conduit that connects directly to the host’s blood vessels.
Blood is drawn through a series of channels within the tick’s foregut. The flow is driven by a combination of negative pressure generated by the tick’s muscular pharynx and the passive influx from the host’s capillary pressure. The tick’s salivary glands continuously inject anti‑hemostatic compounds, ensuring the blood remains fluid throughout the feeding period.
As feeding progresses, the lesion expands, and the tick’s mouthparts may extend deeper into the dermis, occasionally reaching the subcutaneous tissue in larger species such as Ixodes ricinus or Dermacentor variabilis. In these cases, the tick accesses larger vessels, increasing the volume of ingested blood. The engorgement phase can last from several days to over a week, during which the tick can ingest up to 200 mg of blood, representing a substantial proportion of its body weight.