Class Arachnida Flashcards
Class Arachnida includes the ff:
king crab
spiders
scorpions
ticks and mites
General Characteristics of Class Arachnida
Wingless. Head, thorax, and abdomen are not defined. They feed on tissue fluids by means of sucking pharynx.
4 main body parts of Class Arachnids
- Gnasthosoma
- Propodosoma
- Metapodosoma
- Opisthosoma
bears the mouthparts and the plate that bears it, the capitulum or gnathobases
Gnasthosoma
Gnasthosoma bears the mouthparts and the plate that bears it is called
capitulum or gnathobases
bears the first and second pairs of legs
Propodosoma
Bears the third and fourth parts of legs.
Metapodosoma
posterior part behind the fourth pair of legs, the abdomen
Opisthosoma
Two main body parts of Class Arachnids
- Prosoma
a. Gnathosoma (mouthparts)
b. Podosoma (bears the legs) - Opisthosoma (abdomen part)
a. Prosoma and opisthosoma = idiosoma
Two types of Prosoma
Gnathosoma (mouthparts)
Podosoma (bears the legs)
mouthparts
Gnathosoma
bears the legs
Podosoma
abdomen part
Opisthosoma
idiosoma
prosoma and opisthosoma
The mouthparts of arachnids are composed of the following:
Chelicerae
Hypostome
Pedipalps or palpi
a pair of cutting structures
Chelicerae
median structure with recurved teeth for anchorage
Hypostome
segmented appendages lateral to the chelicerae
Pedipalps or palpi
Stages of development of Class Arachnida:
- Egg – oval or spherical
- Larva - with 3 pairs of legs
-
Nymph – with 4 pairs of legs without sexual organs. May have 2-3 nymphal instars before developing into an adult.
a) Protonymph –first instar
b) Deutonymph – second instar
c) Tritonymp – third instar - Adult – with 4 pairs of legs and well developed sexual organs
Three orders of veterinary importance of Class Arachnids
- Acarina – ticks and mites
- Araneida – spiders
- Scorpionidea – scorpions
ticks and mites
Acarina –
spiders
Araneida
scorpions
Scorpionidea
Four Sub-orders of Veterinary Importance under Order Acarina:
- Ixodoidea – ticks
- Mesostigmata – mites
- Trombidiformes – mites
- Sarcoptiformes – mites
2 groups of sub-order Ixodidea
Family Argasidae (Soft ticks)
Family Ixodidae (Hard Ticks)
Soft ticks
Family Argasidae
Hard Ticks
Family Ixodidae
without scrutum
Family Argasidae (Soft ticks)
with scrutum
Family Ixodidae (Hard Ticks)
Family Argasidae (Soft ticks) genera
- Argas, Otobius, Ornithodoros* (AOO)
Family Ixodidae (Hard Ticks) Genera:
Boophilus, Rhipicephalus, Amblyomma, Ixodes, Dermacentor, Hyalomma (BRAIDH)
Important differences between Argasidae and Ixodidae: SCRUTUM
A: absent
I: present
Important differences between Argasidae and Ixodidae: SEXUAL DIMORPHISM
A: not marked
I: marked
Important differences between Argasidae and Ixodidae: MOUTHPARTS AND CAPITULUM
A: ventral
I: anterior
Important differences between Argasidae and Ixodidae: PALPI
A: leg-like
I: rigid
Important differences between Argasidae and Ixodidae: FESTOONS
A: absent
I: generally present
Important differences between Argasidae and Ixodidae: COXAE
A: unarmed
I: armed
Important differences between Argasidae and Ixodidae: EGG LAYING HABIT
A: laid in small batches
I: laid in one large batch
Important differences between Argasidae and Ixodidae: FEEDING HABIT
A: feed moderately and frequently
I: take one large meal and increase in size dramatically
Important differences between Argasidae and Ixodidae: LIFE SPAN
A: live for several years, 5 years or more
I: live for less than one year, rarely 2 years
Important differences between Argasidae and Ixodidae: ADAPTATION TO ENVIRONMENT
A: drought resistant
I: cannot live w/out adequate humidity
Genus Argas species:
- *Argas persicus *(fowl tick)
- Argas reflexus (pigeon tick)
- Argas persicus* common name
fowl tick
- Argas reflexus* common name
pigeon tick
Argas persicus (fowl tick) are common in
chickens, turkeys, pigeons, ducks, ostriches, canaries
Argas reflexus (pigeon tick) are common in
pigeon, doves
Genus Otobius species
- Otobius megnini (spinose ear tick)
It occurs in America and Africa. Larvae and nymphs occur in the ear of dogs, cattle, horses, and all other mammals. Adults are non-parasitic
Otobius megnini (spinose ear tick)
Otobius megnini (spinose ear tick) lays _________ eggs, which may last for 6 months then dies.
500-600 eggs
Pathogenicity of Genus Otobius or Otobius megnini (spinose ear tick)
• Irritation, scratching, and shaking of ears.
• Inflammation, suppurative lesions (bacterial infestation)
Genus Ornithodoros species:
1. O. moubata
2. O. savignyi
3. O. turicata
Larvae do not hatch but molt into nymph inside the egg. Adult and nymphs attack animals.
Genus Ornithodoros
Transmits: Borrelia recurrentis, the cause of relapsing fever in man
Genus Ornithodoros
Genus Ornithodoros transmits this disease
Borrelia recurrentis, the cause of relapsing fever in man
the cause of relapsing fever in man
Borrelia recurrentis
attacks wild and domestic mammals
Ornithodoros moubata
occurs on the livestock in Africa and India
Ornithodoros savignyi
occurs in the U.S.
Ornithodoros turicata
Female lay 2,000 – 20,000 eggs
Ixodine ticks
active, climb up the pinnacle or tip of grasses and attach themselves to passing animals and suck blood
Seed ticks
Unfed ticks live longer than well-nourished ticks
True
Ixodid ticks are classified according to the number of host
- One-host tick
- Two-host tick
- Three-host tick
Larva attaches to a host, molt into nymph and finally adult stage on the same animal, e.g. Boophilus microplus, Boophilus annulatus
One-host tick
Example of one-host tick
1. Boophilus microplus,
2. Boophilus annulatus