[Biology Class Notes] on Tick Life Cycle Pdf for Exam

Ticks are invertebrates in nature, normally 3 to 5 mm long and they belong to Kingdom Animalia.

Systematic Position

• Phylum: Arthropoda 

• Class: Arachnida

• Sub-Class: Acari 

• Order: Ixodida

There are nearly 18 tick genera and about 850 different species. Ticks are external parasites and their source of feed is the blood of mammals, reptiles, amphibians, and birds. Body of Adult tick is ovoid or pear-shaped, having 8 legs.

They are distributed among two major families, Ixodidae namely hard ticks and Argasidae namely soft ticks. 

Hard ticks have their mouthparts at the frontal position, while soft ticks have their mouthparts underlying their body.

The life cycle of a tick is completed after four stages namely egg, larva, nymph, and adult, it requires more than a year to complete a full life cycle. 

Stages in the Life Cycle of Ticks

The adult female tick first fulfills a proper blood meal then the process of mating occurs between an adult male and adult female tick. The female tick then leaves the host and lays eggs in a suitable spot outside the host. 

The eggs are hatched marking the beginning of a six-legged larval stage within a time span of 2 to 8 weeks. After hatching, the larva then remains on the grass waiting for a suitable host to attach. The odor of the host enables the tick to determine the host to get attached with. After attaching to host the larva feeds upon it and undergoes several stages of molting to transform into a nymph.

The larva after feeding on the host for several days acquires a good blood meal and then detaches itself from the host to molt into an eight-legged nymph. The larva molts for two weeks until it develops into an eight-legged nymph and again searches for a suitable host to get attached with for initiation of the next stage. 

At this stage, the tick or larva is sexually matured and sufficient enough to reproduce. When it comes to hard ticks, the male and female ticks first acquire a sufficient blood meal and then initiates the process of mating.

Usually, a female tick takes a longer time of feeding compared to the male tick. After the mating process male tick dies, while the female tick dies after laying eggs.

The life cycle of Tick

Tick-Borne Diseases

As ticks feed on blood meals they transmit a number of infections to the host caused by pathogens like bacteria, viruses, and protozoa.

Some ticks carry pathogens that can cause human diseases namely.

Transmitted to humans mainly by the bite of black-legged ticks. It is mainly a bacterial type of disease that attacks the white blood cells in the body. Symptoms include fever, chills, muscle pain, headache, fatigue, and stomach pain. 

It is a protozoan type disease caused by Babesia microti parasite mainly transmitted by black-legged ticks. Symptoms include low blood pressure, anemia, and flu-like symptoms.

It is a viral infectious disease caused by the colorado tick fever virus transmitted to humans by Rocky Mountain wood ticks.

Transmitted to humans by lone star ticks. Symptoms mainly include fever, headache, nausea, stomach pain, and diarrhea.

The most common tick-borne disease is Lyme disease, It is a bacterial type disease mainly caused by deer ticks.

Symptoms include Fever, migraine, cranial nerves palsy, carditis, fatigue, influenza-like illness, and rash, which later gets bigger and appears as a circular red ring.

It is also a bacterial type of disease. Transmitted to humans through the bite of infected soft ticks mainly of Ornithodoros species. Symptoms include recurring high fever, rigors, headaches, muscle, and joint pain, flu-like symptoms.

It is transmitted to humans by groundhog ticks and black-legged ticks. A type of viral infectious disease. Symptoms include fever, headache, vomiting, loss of coordination, and seizures.

Transmitted by the Rocky Mountain wood ticks, American dog ticks, and brown dog ticks. Symptoms include fever, headache, myalgia, altered mental status, and rash.

It is caused by the TBE virus and is transmitted to humans through infected species of ticks called Ixodes.

Transmitted to humans by dog ticks, wood ticks, and the lone star ticks. Symptoms include fever, skin ulcer, swelling in glands (lymph nodes).

Did You Know?

• Nutrition of ticks fully depends upon blood meals, they feed upon the blood of mammals, reptiles, amphibians, and birds.

• Ticks cannot survive on a single host for their entire lifespan therefore they change their host at every different stage of their life cycle as they totally depend upon the host for feeding and growing.

• Ticks after every stage search a potential host to get attached with, lying on the grasslands they wait for the suitable host to arrive, and once they identify the odor of butyric acid of any mammals they get attached to it.

• An adult female tick can lay several thousand eggs from 2000 to 18000 approximately during its entire lifespan.

• Ticks prefer warm and moist areas to live. In humans, they are mostly found in armpits, groin, or scalp.