![]() This waiting ‘ambush’ behaviour in ticks is called ‘questing’. To facilitate host attachment, ticks crawl onto the end of low growing vegetation then extend and wave around their receptor equipped front legs and wait to ambush a host. This specialised organ is sensitive to heat, carbon dioxide and other chemosensory cues given off by a potential host. To this end ticks (and mites) possess a unique sensory organ on their front legs called Haller’s organ. Being obligate parasites, it is vital that ticks are able to efficiently find a host. Most ticks spend most of their life waiting for a new host and there is high mortality due to predation and starvation during this ‘waiting’ time. In contrast, the introduced Australian Cattle Tick (Rhipicephalus australis) is a one-host tick and from the time it hatches from its egg and is picked up by a host, usually a passing cow, it will go through the life stages of larva, nymph and then adult on the one host animal. The blood engorged fertilised females drop off the final host and lay their eggs before dying. The nymph then again moults and emerges as an adult that again requires a new host on which to feed and mate. It then moults to become a nymph which again requires a host to feed on before dropping off. This three-host lifecycle sees a hatched larva attach to a host, feed, then drop off. These hosts do not need to be the same species. Most ticks have three discrete hosts as part of their lifecycle. Female Ixodidae ticks lay a single large batch of eggs before dying, whilst female Argasidae lay several smaller batches of eggs. At the family level, ticks are classified as either hard ticks (Ixodidae), which have a hardened scutum (middle part of the thorax) or soft ticks (Argasidae), which lack this feature. ![]() They are all parasitic blood suckers that undergo several moults, usually interspersed with blood feeds, before the final moult into a reproductive adult. That said, how many of us have stopped to think about the pesky creature in question?Īt the class level ticks are members of the eight-legged Arachnida along with their well-known spider and scorpion relatives and have been around for at least 300-400 million years. For any of us who spend time in the bush this is an all too familiar scenario as ticks are unfortunately a fact of life for those who enjoy or work in the outdoors. Sure enough, in the centre of a red circular spot was the back end of a tick that was now upended, firmly attached and happily feeding on my blood. Resisting the urge to scratch the affected area I ducked behind a convenient tree and inspected the site in question. Stomping through the bush I experienced the faintest of, all that I can describe as, chemical zaps and knew that I’d picked up another very unwelcome hitchhiker.
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