Hard Ticks

The family Ixodidae is by far the largest and economically most important family with 13 genera and approximately 650 species.
The most important species in North America are Ixodes pacificus, Ixodes scapularis (dammini), Ixodes ricinus, Dermacentor variabilis, Rhipicephalus sanguineus, Amblyomma americanum, Haemaphysialis leporispalustris, Boophilus annulatus and Boophilus microplus.

The hard ticks are flattened dorsoventrally in the unfed state, possess a marginal outline which tapers toward the anterior, and the mouthparts are clearly visible. In the adult stage, a sclerotized dorsal plate (scutum) is evident and this is often ornate with patterns in white or gold against a brown or grey background.
Hard ticks feed for extended periods of time on their hosts, varying from several days to weeks, depending on such factors as life stage, host type, and species of tick.

The outside surface, or cuticle, of hard ticks actually grows to accommodate the large volume of blood ingested, which, in adult ticks, may be anywhere from 200-600 times their unfed body weight.

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Soft Ticks

The family Argasidae comprises 5 genera and approximately 170 species.
The 5 genera are: Argasinae (e.g. spp. Argas reflexus, Argas vespertilionis), Ornithodorinae (e.g. spp. Ornithodoros hermsi, Ornithodoros coriaceus, Ornithodoros moubata), Otobinae (e.g. sp. Otobius megnini), Antricolinae, Nothoaspinae.

The soft ticks have an oval or pear-shaped outline with the anterior body region broadly rounded. The mouthparts are difficult to see from a dorsal view. The soft ticks are inornate and have a granulated leathery appearance.

Soft ticks feed for short periods of time on their hosts, varying from several minutes to days, depending on such factors as life stage, host type, and species of tick. The feeding behavior of many soft ticks can be compared to that of fleas or bedbugs, as once established, they reside in the nest of the host, feeding rapidly when the host returns and disturbs the contents. The outside surface, or cuticle, of soft ticks expands, but does not grow to accommodate the large volume of blood ingested, which may be anywhere from 5-10 times their unfed body weight.

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The Cuticle

The integument is composed of the epidermis and the cuticle. The cuticle is the dead, outer part of the integument. It is secreted by the epidermis which forms the inner, living part of the integument.

The ticks integument serves as a body covering, as the primary protection against water loss and also as the exoskeleton. This provides protection against mechanical and other types of physical damage.

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Nervous System

The nervous system is very close associated with the circulation system. The "brain", termed synganglion, is located centrally at the level of the second coxae.

The synganglion is divided into two parts by the esophagus. The pre-esophagus-part consists of the protocerebrum, the optic lobes the cheliceral and pedipalpal ganglia, and the stomodeal pons or bridge. The post-esophageal part serves the four pair of legs.

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Locomotion

Ticks are typically acarine in having hexapod larvae and octapod nymphs and adults. The legs are jointed and divided into seven segments: coxa, trochanter, femut, genu, tibia, tarsus and pretarsus.

While the legs are primary ambulatory, they may be modified to serve other functions. The legs of Acari may be smooth or variously ornamented and usually possess a number of tactile and sensory hair. On the dorsal surface of tarsus I, e.g., the Haller`s organ, a complex sensory structure is found.

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