Why are blacklegged ticks called three-host ticks?

Why are blacklegged ticks called three-host ticks?

• A. Because they feed on host three times in a day
• B. Because they require three different species to complete their life cycle
• C. Because each mobile life stage must find and feed on an appropriate host (larvae, nymph, and adult)
• D. Because they have three hosts simultaneously

Answer: (C)

The main idea is that blacklegged ticks complete their life cycle by feeding at three distinct mobile stages, each on a different host. A tick hatches as an unfed larva, finds and feeds on a small animal or bird, then drops off to molt into a nymph. The nymph then seeks another host to feed, drops off again to molt into an adult, and finally feeds one last time on a larger host. Because there are three separate feeding events on three different life stages, this type of tick is called a three-host tick. That’s why the best choice says that each mobile life stage must find and feed on an appropriate host (larvae, nymph, and adult). The other ideas don’t fit the biology: there isn’t three feeds in one day, no requirement for three specific species to complete the cycle, and they don’t feed on three hosts simultaneously.

The main idea is that blacklegged ticks complete their life cycle by feeding at three distinct mobile stages, each on a different host. A tick hatches as an unfed larva, finds and feeds on a small animal or bird, then drops off to molt into a nymph. The nymph then seeks another host to feed, drops off again to molt into an adult, and finally feeds one last time on a larger host. Because there are three separate feeding events on three different life stages, this type of tick is called a three-host tick.

That’s why the best choice says that each mobile life stage must find and feed on an appropriate host (larvae, nymph, and adult). The other ideas don’t fit the biology: there isn’t three feeds in one day, no requirement for three specific species to complete the cycle, and they don’t feed on three hosts simultaneously.