Ticks are tiny creatures called parasites. A parasite can be a plant or an animal which feeds on a host (another plant or animal). Ticks are parasites which feed on the blood of lots of types of animals and sometimes people.
Ticks do not have wings to fly. They also cannot jump. They travel by walking on the ground and up plants, or are transported by birds and animals. Then they wait for a host (an animal or person) to pass by. When the host comes near, they drop onto it or hook onto it with special hooks on their legs. Some types of tick live in the burrows or nests of animals and birds.
Ticks vary in colour and in size, depending on the type of tick, whether it is male or female, and whether it is a baby, juvenile or an adult. The tick's colour and size also depends on whether it has fed or not.
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 nymph ticks (juvenile) 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 stick out from the pet's fur.
Unfed, the largest tick is a female. She is about the size of a sesame seed on a burger bun (3mm) and she is the same shape (oval and flat). After she has fed, she swells up to many times her original size to about 11mm.
Male ticks are a bit smaller than females and are about 2.5mm.
Nymph ticks are even smaller and are about 1.5mm.
Newly-hatched ticks (called larvae) are the tiniest. They can be smaller than a poppy seed and are about 0.5mm. Once they are full of blood, ticks get bigger and much more round because their soft bodies expand like a balloon full of water.
The most common tick in the UK to bite humans hatches from an egg, then goes through several stages before dying. This is called a "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 they only have six legs. After they have hatched, they need to feed to gain strength and to grow to their next stage when they become nymphs. After they have fed, they shed their skin. This is called moulting. Under the old skin is a new one which also has the final pair of legs.
The nymph ticks look for a host and feed again. Then they moult for a last time and become adult males or female ticks.
The adult males and females look for a host. The female feeds so that she has lots of strength to lay several thousand eggs. The male fertilizes her eggs while they are on the host. Then the female drops off to lay her eggs. The eggs hatch and the cycle begins again.
Different types of ticks have different ways in which they feed and breed and they can live from several months to several years.
In the UK and Ireland, there are over 20 species of tick. Some have hard bodies (with a hard plate on their backs) and some have soft, leathery bodies. Because of these differences, the two families of tick are called hard ticks and soft ticks. There are many species of ticks in each of these families. It is usually a species of hard tick that is found on pets or people, although some types of soft ticks will bite them too.
Ticks normally choose wildlife and farm livestock to be their hosts. However, people and pets send out the same signals as the tick's usual hosts. These signals come from body heat and the breath and skin of the host. The tick recognises these signals and thinks that we, or our pets, will be a suitable meal. We are just in the wrong place at the wrong time.
Some ticks can carry organisms in their saliva. When they bite, the saliva can enter the bloodstream of the host and this can make them ill.
Because winters are warmer, and because there have been changes in farming methods, as well as other factors, there are more ticks about. Ticks are also spreading into new places where they weren't found before. Because of this, and because more people tend to be involved in outdoor activities, a greater number of people get bitten by ticks. This means that more people get diseases from the ticks.
Diseases passed on by ticks are called tick-borne diseases. The most common tick-borne disease to affect people in the UK and Ireland is Borreliosis, which is also called Lyme borreliosis or Lyme disease.