Phylum Arthropoda

Subphylum Chelicerata

Phylum Arthropoda

Subphylum Chelicerata

Characterized by having a pair of appendages called chelicerae on each side of their mouth.

They have no antennae.

Examples of Chelicerates

Examples of Chelicerates

• Horseshoe Crabs

Examples of Chelicerates

• Horseshoe Crabs• Spiders

Examples of Chelicerates

• Horseshoe Crabs• Spiders• Scorpions

Examples of Chelicerates

• Horseshoe Crabs• Spiders• Scorpions• Ticks and Mites

Examples of Chelicerates

• Horseshoe Crabs• Spiders• Scorpions• Ticks and Mites• Harvestmen

Examples of Chelicerates

• Horseshoe Crabs• Spiders• Scorpions• Ticks and Mites• Harvestmen• Pseudoscorpions

Chelicerae of a horseshoe crab are chelate.

Chelicerae of a spider.

Spiders’ chelicerae have fangs used to inject venom into their prey.

Scorpions’ chelicerae are chelate.

Chelicerates’ second pair of appendages are called pedipalps.

A horseshoe crab’s pedipalps are chelate and are used to hold food. They look much like their legs.

Scorpions also have chelate pedipalps. They use them to hold their prey while they envenomate them with their poison sting.

Spider pedipalps look like their legs. They use them for walking.

Some male spiders have bulbs at the end of their pedipalps which they use to hold sperm as they shove it into the females reproductive opening.

Pseudoscorpions’ pedipalps are chelate. They have tiny spurs on them that deliver venom when they close their pedipalps on their prey.

Since the term venom has come up several times, this is a good time to define it.

Since the term venom has come up several times, this is a good time to define it.

Venom is a mix of proteins animals use to kill or paralyze their prey.

Since the term venom has come up several times, this is a good time to define it.

Venom is a mix of proteins animals use to kill or paralyze their prey. Venom must be injected.

Since the term venom has come up several times, this is a good time to define it.

Venom is a mix of proteins animals use to kill or paralyze their prey.

Venom must be injected. Poisons are ingested (swallowed).

Spider bites leave two small puncture wounds.

If the injected venom is particularly potent, the digestive enzymes in it can cause a great deal of tissue damage.

Ticks and mites also have chelicerae and pedipalps.

Ticks and mites also have chelicerae and pedipalps.

Ticks pose a public health issue. The deer tick is the vector for Lyme Disease and Rocky Mountain Spotted Fever is spread through a tick’s bite.

Males do not develop a swollen abdomen. They usually feed on plants.

Females feed on blood. They engorge with blood to provide nutrients for their eggs.

Chiggers are mite larvae. They feed by injecting enzymes that digest a tunnel. Then they enter the tunnel and feed on cellular fluids.

Some people are extremely allergic.

They like places where your clothing is tight to your skin.