How does a tick drink human blood? - briefly
A tick penetrates the skin with its barbed hypostome, releases saliva containing anticoagulants to keep blood fluid, and then draws the host’s blood through its fore‑gut into its body. The feeding can continue for several days as the parasite expands its abdomen with the ingested blood.
How does a tick drink human blood? - in detail
Ticks attach to the skin using their fore‑legs, which locate a suitable spot through sensory organs that detect heat, carbon dioxide and movement. The second pair of legs then anchors the body, while the third and fourth pairs press the mouthparts into the epidermis.
The mouthparts consist of a dorsal capsule (the scutum) and a ventral feeding tube called the hypostome. The hypostome bears backward‑pointing barbs that lock the tick in place after penetration. Simultaneously, the tick secretes a cement‑like protein from its salivary glands, hardening around the insertion site and preventing dislodgement.
Saliva contains a cocktail of bioactive compounds:
- anticoagulants (e.g., apyrase, tick anticoagulant peptide) that inhibit platelet aggregation;
- vasodilators that expand capillaries;
- anti‑inflammatory agents that suppress host immune responses;
- analgesic peptides that reduce pain perception.
These substances keep blood flowing freely and mask the bite from the host’s detection mechanisms.
Feeding proceeds in two phases:
- Slow‑phase – lasting several hours to days, the tick draws plasma through the hypostome at a rate of 0.5–1 µL per hour. During this period, the tick’s weight increases modestly.
- Rapid‑engorgement – triggered by hormonal signals within the tick, the gut expands dramatically, and intake accelerates to several milliliters per hour. The tick’s body can swell up to 100 times its unfed size.
Throughout ingestion, the tick’s fore‑gut filters out red blood cells, while the mid‑gut stores the meal and initiates digestion. Enzymes break down hemoglobin, and excess water is excreted via the rectal canal.
After reaching full engorgement, the tick releases the cement, withdraws the hypostome, and drops off the host. The detached tick remains attached to its environment until it molts or reproduces.