Module 10: Veterinary Ectoparasites

Module 10.2: Ticks

Tick anatomy

Ticks are part of the Arachnida class.  Common features of ticks include: 8 legs, a mouthpart called a capitulum, a thorax that is fused to the body with no head or antennae.  They are obligate ectoparasites that are blood-sucking at all life stages.  The common ticks of veterinary importance are: Ixodes spp.Dermacentor spp., Amblyomma americanumRhiphicephalus sanguineus, and Otobius spp.

Diagram of tick anatomy
Tick Anatomy

Types of Ticks

Ticks can be divided into TWO major types: hard ticks and soft ticks based on the presence or absence of a scutum.

Hard Ticks (Ixodidae)

This is the most common veterinary species in North America.  The dorsal surface of all stages has a scutum (see diagram above of female tick).  In male ticks, the scutum covers the entire dorsal surface, wherein female ticks, nymphs, and larvae have a scutum that covers only the anterior half. The capitulum (mouthparts) arises from the anterior of the body in each stage.

There are two subclasses of hard ticks based on the pattern on the scutum: inornate (no pattern) or ornate (white or iridescent pattern).

Examples of inornate and ornate hard ticks
Inornate and Ornate Hard Ticks

Soft Ticks (Argasidae)

Soft tick example
Soft tick

There are very few species of soft ticks of veterinary importance in North America.  In comparison to the hard ticks, they do not have a hard plate (scutum).  Their mouthparts (capitulum) are tucked up underneath their bodies ventrally.  Soft ticks live in habitats such as heavily wooded areas or under rocks as the lack of a hard scutum requires them to be adapted to sheltered/protected niches.

Summary table and charts

Table 10.2: Tick Summary Table

Tick Type

Scutum

Capitulum (mouthparts) location

Habitat

Hard Tick
yes Anterior of the body Wide diversity
Soft Tick
no Tucked underneath the body ventrally Woods or rocks- need protection

 

Tick identification flow chart
Tick identification flow chart
Tick identification chart
This flow chart can be found in your parasite laboratory manual and will be used to guide you through the laboratory exercise.

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