What is a tick?
For those who do know, it might seem strange to think that some people have no idea what ticks are. But the fact is that there are a large number of people who don't know, or who only have a vague idea. Here is a small selection of some of the ways that a tick has been described.
- A biting fly that has a high-pitched buzz. Wrong! This describes a mosquito.
- A slimy thing, with eyes on stalks. Wrong! This describes a slug.
- A maggot that burrows into your skin. Wrong! This describes a Bot fly maggot.
- A blood-sucking worm found in ponds and rivers. Wrong! This describes a leech.
- A hopping insect found in long grass. Wrong! This describes a grasshopper.
To take defensive measures against ticks, it helps to be able to recognise them. Since there are hundreds of species of tick, the descriptions here are general.
So, exactly what is a tick?
Ticks are small parasites, which feed on the blood of mammals, birds, reptiles and humans. They belong to the same family as spiders.
Description
Ticks vary slightly in colour (ranging from reddish to dark brown or black), and differ in size, depending on the age and sex of the tick, and whether it has fed.
Here we see a male and female sheep tick (images are very much larger than life-size).
Female adult sheep tick. |
Male adult sheep tick. |
Tick sizes
Ticks are very tiny. Many people think of them as being quite big, but this is because they are used to seeing a balloon-like tick on a dog or cat. This is how the large nymphs or adult ticks look after they have fed for several days and are full of blood. By this time, they look like a pink or blue-black balloon and often protrude from the pet's fur.
A feeding tick (blue-black colouring). |
The fully fed tick (right) is very much larger than the unfed one (left). |
An un-fed adult female is approximately 3mm (sesame-seed-size) and she is small, oval and flat. When fully engorged she can reach 11mm. Males are smaller, at approximately 2.5mm. Nymphs are smaller still, at around 1.5mm and the larvae are a tiny 0.5mm.
Here we can see the different sizes from an adult to larva.
Ticks at different stages, against a centimetre rule. |
Ticks do not have wings, they cannot jump or fly.
The tick life cycle
Like the rest of their "relations"; the spiders, scorpions, mites and harvestmen, ticks have eight legs. However, when they hatch from their eggs (at this stage, they are called "larvae"), they only have six legs. They immediately need to feed to gain strength and to grow and moult to their next stage (when they become nymphs).
At the nymph stage they have eight legs. They continue to feed and moult, to the last stage, which is the adult.
Ticks in the UK
There are two families of ticks that can be found in the United Kingdom:
- Argasidae - which are a 'soft tick' family. They are called 'soft ticks' because they have a spongy, wrinkled back, which extends like a hood over their head and mouth parts.
- Ixodidae - which are a 'hard tick' family. They are called 'hard ticks' because they have a hard plate-like shield that covers their backs. Unlike soft ticks, the head and mouth parts can be seen from above.
As a hard tick feeds, the hard shield on the back appears smaller, and more towards the head of the tick, as its soft body swells up with blood.
There are many species of ticks in each of these families. It is usually a species of hard tick that is found on domestic pets or people, although some soft ticks will bite humans.
The most common tick to bite people in the UK is the Sheep tick (Ixodes ricinus), which also goes by several other names, such as the Wood tick, and the Castor bean tick. The other more common ticks to bite people and their pets are the Hedgehog tick (Ixodes hexagonus), and the Ornate cow / Marsh tick (Dermacentor reticulatus).
You can read more about ticks on the BADA-UK website.
