Subphylum Chelicerata

Horseshoe crab, spiders, ticks, mites, scorpions, sea spiders

Six pair of appendages: pair of chelicerae, pair of pedipalps, and four pairs walking legs

No mandibles, no antennae

Class Merostomata
Horseshoe crab.

Tagmata = cephalothorax, abdomen, tailpiece (telson)

Carapace or shell has two compound eyes and two simple eyes

Class Arachnida
Spiders, scorpions, ticks, mites, daddy longlegs and others

Tagmata = cephalothorax and abdomen joined together by pedicel (except ticks and mites with no division of tagmata)

Chelicerae and pedipalps are modified into claws and fangs

No mandibles, no antennae

Poison glands and stingers in most

No mandibles so sucking mouthparts.

Respiration --

Excretory system -

Reproduction - variable males - pedipalps or in scorpions use spermatophore

Spinnerets / silk glands