Demonstration Sheets for Chelicerates (Lab 8)
All specimens (except for the bacteria, B. burgdorferi) this week are classified as:
Phylum Arthropoda; Subphylum Chelicerata, Class Arachnida, Subclass Acari
th
[Figure and page numbers are from Roberts & Janovy 8 ed.]
Tick and Mite
Move the slide back and forth and compare the representative specimens.
92W 6110, Dissecting Scope
Family Ixodidae (= hard ticks)
Ixodes adult
Vector for Lyme Disease caused by the bacterium Borrelia burgdorferi. The first
case of Lyme Disease in the US was reported in 1962. Your text points out that today
half of all arthropod transmitted diseases in the US are B. burgdorferi making it the
leading arthropod-borne disease in the country. See Fig. 41.3, p. 642.
14-1 %, 4X
Family Ixodidae (= hard ticks)
Adult ticks
These hard ticks were removed from a dog. They are engorged with the dog’s blood.
Specimen; Dissecting Scope
Kingdom Eubacteria, Borrelia burgdorferi
LYME DISEASE
This is the spirochaete bacterium responsible for Lyme Disease. It is transmitted
by nymphs of deer ticks, Ixodes. A distinctive circular rash surrounding the tick bite
usually appears anywhere from 3 days to a month after the victim is bitten. (See the
photos in the adjacent folder.) At present, the bacteria respond to antibiotics. Untreated
victims, however, can experience pain in their joints which, if untreated, will eventually
develop into crippling arthritis.
Carolina 29-4486 (Z30), 40X
Family Argasidae (= soft ticks)
Soft Tick
“Soft ticks” are distinguishable from “hard ticks” by the morphology of the head
region. The capitulum of soft ticks is not visible from a dorsal perspective (= from
above). Often found in nesting and “dust-bath” areas used by the birds and mammals
upon they feed, some species in this family can inflict a painful bite on unwary campers.
See Fig. 41.9, p. 647.
11-8 Ornithodoros, Dissecting Scope
Family Trombiculidae
Chiggers or “red bugs”
Only larval stages feed on mammals. (Note that larvae have 6 legs.) See Fig.
41.20 (p. 654). On humans they tend to congregate in areas restricted by clothing (e.g.
ankles, crotch, waistline, & armpits). They are easily removed by scratching if noticed.
Chiggers do not burrow into the dermal layer as do scabies mites. They bite and suck
up a blood meal. The itching is thought to be the result of a immune reaction to the
salivary secretions of the mites.
P9.442, 10X
Family Demodicidae
Demodex
Most people have these symbionts in the hair-follicles around their noses and
eyelashes. Infection is usually harmless and goes unnoticed. The dog follicle mite, D.
canis, however, can cause a life-threatening mange disease in some breeds. See Fig.
41.19 (p. 653).
PS 3485, 40X
Family Sarcoptidae
Scabies or Mange Mite
These mites are commonly found on feral and abandoned dogs and readily
transfer themselves to humans whereon they cause extremely intense itching. See Fig.
41. 26 (p. 657).
92W 6252, 10X
Family Sarcoptidae
Scabies Mite in situ
This is a cross-section through the dermal layer of mammalian skin with
“tunnels” occupied by scabies mites.
92W 6253, 10X
Human Scalp
No mites are present in the keratinized layer.
Triarch HI 1-3, 4-10X
Dust Mite
These mites cause a condition known as house dust allergy that can be severely
discomforting to the sufferers. See Figs. 41-27 (p. 657).
92W 6230, 40X
Family Varroidae
Varroa Mite
One of two families (the other being the tracheal mite) of introduced mites that
are having a devasting impact upon honey bees in the United States. Varroa mites
typically feed on pupae of bees in the hive, but may feed on adults during the winter.
92W 6524, 4X