Who is a tick? - briefly
A tick is a blood‑sucking arachnid of the order Ixodida that parasitizes mammals, birds, reptiles, and amphibians. It serves as a vector for pathogens such as the bacterium that causes Lyme disease.
Who is a tick? - in detail
Ticks are obligate hematophagous ectoparasites belonging to the subclass Acari, order Ixodida. Two principal families dominate: Ixodidae (hard ticks) with a scutum covering the dorsal surface, and Argasidae (soft ticks) lacking a scutum and exhibiting a more flexible body outline. Both families possess chelicerae adapted for piercing host skin and a hypostome equipped with barbs that anchor the parasite during blood ingestion.
Morphologically, ticks display four life stages—egg, larva, nymph, and adult—each requiring a blood meal to advance. The developmental sequence proceeds as follows:
- Egg: laid in clusters on the ground, hatching into six-legged larvae.
- Larva: attaches to a host, feeds, then detaches to molt into a nymph.
- Nymph: six-legged to eight-legged transition, feeds again, then molts into an adult.
- Adult: sexual dimorphism appears; females engorge heavily, producing thousands of eggs, while males typically feed minimally and focus on mating.
Feeding periods range from several hours to days, depending on species and host. During attachment, ticks secrete saliva containing anticoagulants, immunomodulators, and enzymes that facilitate prolonged blood intake and suppress host defenses. Salivary components also serve as vectors for a broad spectrum of pathogens, including bacteria (e.g., Borrelia burgdorferi), protozoa (e.g., Babesia spp.), and viruses (e.g., tick-borne encephalitis virus). Transmission occurs primarily during the later phases of feeding when salivary secretions are most abundant.
Ecologically, ticks inhabit diverse habitats—from temperate forests to arid scrublands—and rely on environmental cues such as humidity and temperature to locate hosts. Questing behavior involves climbing vegetation and extending forelegs to latch onto passing vertebrates. Host range encompasses mammals, birds, and reptiles, with some species exhibiting strong host specificity while others are generalists.
Control strategies focus on habitat management, chemical acaricides, and host-targeted interventions. Effective measures include:
- Regular vegetation mowing to reduce questing height.
- Application of permethrin-treated clothing for personal protection.
- Use of acaricide-impregnated collars on domestic animals.
- Vaccination of livestock against tick-borne diseases where available.
Understanding tick biology, life-cycle dynamics, and vector capacity is essential for mitigating the health risks they pose to humans, wildlife, and livestock.