Where are the respiratory tracts in a tick? - briefly
Ticks breathe through two dorsal spiracles situated on the posterior part of the idiosoma near the rear margin. These openings lead to a simple tracheal network that supplies air directly to the organism’s internal tissues.
Where are the respiratory tracts in a tick? - in detail
Ticks possess a tracheal respiratory system rather than lungs. Air enters through external openings called spiracles, which are situated on the dorsal surface of the idiosoma. In hard ticks (family Ixodidae), a single pair of spiracles is positioned near the coxae of the fourth pair of legs, slightly posterior to the scapular plates. Each spiracle leads to a short tracheal tube that connects to a larger tracheal trunk extending laterally toward the body’s interior. The trunk branches repeatedly, forming fine tracheoles that deliver oxygen directly to the surrounding tissues and cells.
Soft ticks (family Argasidae) exhibit a different arrangement. They typically have multiple spiracular openings—often one pair per leg segment—distributed along the lateral margins of the idiosoma. These spiracles also feed into short tracheae that merge into a central tracheal network, providing a more extensive surface for gas exchange.
Inside the body cavity, the tracheal system is surrounded by hemolymph within the hemocoel. The tracheoles terminate close to the cells, allowing diffusion of oxygen without the involvement of circulatory transport. The system is sealed by a cuticular valve that can close the spiracle, reducing water loss during prolonged attachment to hosts.
Key structural points:
- Spiracles: dorsal pair in hard ticks, multiple lateral pairs in soft ticks.
- Tracheae: short tubes from each spiracle, merging into a central trunk.
- Tracheoles: fine branches delivering oxygen to tissues.
- Cuticular valves: regulate opening to prevent desiccation.
This arrangement enables ticks to respire efficiently while remaining attached to hosts for extended periods.