Arachnida

PARASITES ARTHROPODS

Classification

Arthropod Classification - copyright nabrown RVC

The phylum arthropoda is divided into several subphylums including Chelicerata (which includes the arachnids), Myriapoda, Hexapoda (which includes the insecta), Crustacea and Trilobitomorpha. These are then divided into many classes. The two of major veterinary importance are the insecta and arachnida classes.

The arachnids includes well known veterinary species such as ticks and mites. It also includes scorpions and spiders. Most of the structure and function of the arachnids is similar to the insecta.

Structure and Function

• Only two body divisions
  • Cephalo-thorax
  • Abdomen

• Three pairs of legs in the larval stages or four pairs of legs during the nymphal and adult stages

• No wings

• No antennae

• No compound eyes

• Small size
  • E.g. Ticks are under 1cm in length
  • E.g. Mites are under 1mm in length

Life cycles

• The larva (also called seed tick) develops from the egg

• The nymphal stage follows the larval stage

• The nymph then develops into an adult (i.e. sexually mature)

Ticks

Mites