How are the chelicerae of spiders and horseshoe crabs different?
In true spiders, the chelicerae are modified into fangs with poison glands, while the pedipalps of the males are modified for copulation. In horseshoe crabs the second appendages are walking legs that do not differ from the other four pairs; all five pairs of walking legs bear claws.
How does the horseshoe crab differ from the scorpions?
Horseshoe crabs are more closely related to spiders, ticks and scorpions than they are to true crabs. Like other arthropods, they have a hard shell, or exoskeleton, a segmented body and jointed legs. Horseshoe crabs are in a class of their own – Merostomata – which means “legs attached to the mouth.”
What makes chelicerates different from other arthropods?
Common name: chelicerates, arachnids Like all arthropods, they have a segmented body and segmented limbs and a thick chitinous cuticle called an exoskeleton. Chelicerates have two body segments; a cephalothorax and an abdomen. They have no antennae, but have six pairs of appendages.
Which of the following characteristics are unique to the chelicerata?
Chelicerates have two body segments (tagmenta) and six pairs of appendages. Four pairs of appendages are used for walking and two (the chelicerae and the pedipalps) are used as mouthparts. Chelicerates have no mandibles and no antennae.
Why do humans need horseshoe crabs?
Why are horseshoe crabs important? Horseshoe crabs are an important part of the ecology of coastal communities. Their eggs are the major food source for shorebirds migrating north, including the federally-threatened red knot.
Is a horseshoe crab an isopod?
An Isopod is any of numerous crustaceans of the order Isopoda, characterized by a flattened body bearing seven pairs of legs and including the sow bugs and gribbles. A Sow Bug is also known as a Woodlouse. The horseshoe crab, “Limulus polyphemus” is an arthropod that is more closely related to spiders than crabs.
What are three characteristics of arachnids?
Like all arthropods, arachnids have segmented bodies, tough exoskeletons, and jointed appendages. Most are predatory. Arachnids lack jaws and, with only a few exceptions, inject digestive fluids into their prey before sucking its liquefied remains into their mouths.
What do horseshoe crabs use pedipalps for?
Five pairs of walking legs or pedipalps enable the horseshoe crab to easily move along benthic sediments. Each has a small claw at the tip except the last pair. The last pair of legs has a leaflike structure at the terminal end that is used for pushing and clearing away sediments as the crab burrows into marine bottom.
What is the largest Chelicerate class?
Arachnida
The largest class of extant chelicerates is Arachnida, which includes spiders, ticks, mites, daddy longlegs, and scorpions, among others. Eurypterida is an extinct class that predates the earliest fishes.
What are the five characteristics of arachnids?
Arachnids have four pairs of legs, specialized appendages, and a fused head and thorax. Arachnids include spiders, daddy-long-legs, scorpions, and ticks.
