What happens when a tick feeds on blood? - briefly
During a blood meal, a tick inserts its hypostome, injects anticoagulant saliva, and gradually draws host blood while its body swells, potentially transmitting pathogens. After engorgement, it detaches to digest the intake over several days.
What happens when a tick feeds on blood? - in detail
Ticks attach to the host’s skin using their chelicerae and a barbed hypostome that penetrates epidermal layers. The mouthparts secrete a complex saliva containing anticoagulants (e.g., apyrase, tick anticoagulant peptide), vasodilators, and immunosuppressive proteins. These agents prevent clot formation, maintain blood flow, and diminish the host’s inflammatory response, allowing uninterrupted feeding for several days.
During the blood meal, the tick draws fluid through a dorsal canal into its foregut. The ingested blood is stored in the midgut, where it is rapidly diluted with tick-derived proteins that buffer pH and inhibit bacterial growth. Digestive enzymes, primarily cathepsins and peptidases, break down hemoglobin and plasma proteins into amino acids and peptides for absorption. The midgut epithelium transports nutrients into the hemolymph, supporting rapid body expansion.
Engorgement progresses through distinct phases:
- Early phase (0‑24 h): Minimal volume intake; saliva secretion predominates.
- Rapid expansion (24‑72 h): Blood volume increases exponentially; weight can rise 100‑fold.
- Late phase (72‑96 h): Tick reaches maximum size; metabolic rate slows as digestion completes.
Pathogen transmission often occurs during the early to mid phases, when salivary compounds facilitate entry of bacteria, viruses, or protozoa into the host’s bloodstream. The tick’s salivary glands act as a reservoir, releasing infectious agents while feeding.
After detachment, the tick excretes excess water and ions via the Malpighian tubules, producing a concentrated urine that is expelled through the anus. The engorged tick then enters a quiescent period to molt or lay eggs, depending on its life stage.