28–2 Groups of Arthropods

February 5, 2018 | Author: Anonymous | Category: Science, Biology, Zoology, Entomology
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Biology

Slide 1 of 42 Copyright Pearson Prentice Hall

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28–2 Groups of Arthropods

Slide 2 of 42 Copyright Pearson Prentice Hall

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28–2 Groups of Arthropods

How are arthropods classified?

Slide 3 of 42 Copyright Pearson Prentice Hall

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28–2 Groups of Arthropods

28–2 Groups of Arthropods

Arthropods are classified based on the number and structure of their body segments and appendages—particularly their mouthparts. The three major groups of arthropods are:

• crustaceans • spiders and their relatives • insects and their relatives Slide 4 of 42 Copyright Pearson Prentice Hall

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28–2 Groups of Arthropods

Crustaceans

What are the distinguishing features of the crustaceans?

Slide 5 of 42 Copyright Pearson Prentice Hall

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28–2 Groups of Arthropods

Crustaceans

Crustaceans Crustaceans are primarily aquatic. This subphylum includes crabs, shrimps, lobsters, crayfishes, and barnacles.

Slide 6 of 42 Copyright Pearson Prentice Hall

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28–2 Groups of Arthropods

Crustaceans

Crustaceans typically have two pairs of antennae, two or three body sections, and chewing mouthparts called mandibles. Abdomen

Cephalothorax

Mandible

First antenna Second antenna Slide 7 of 42

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28–2 Groups of Arthropods

Crustaceans

The crayfish has a body plan that is typical of many crustaceans.

The anterior cephalothorax is formed by fusion of the head with the thorax. Cephalothorax

Slide 8 of 42 Copyright Pearson Prentice Hall

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28–2 Groups of Arthropods

Crustaceans

The thorax lies just behind the head and houses most of the internal organs.

Slide 9 of 42 Copyright Pearson Prentice Hall

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28–2 Groups of Arthropods

Crustaceans

The abdomen is the posterior part of the body.

Abdomen

Slide 10 of 42 Copyright Pearson Prentice Hall

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28–2 Groups of Arthropods

Crustaceans

The carapace is the part of the exoskeleton that covers the cephalothorax.

Carapace Slide 11 of 42 Copyright Pearson Prentice Hall

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28–2 Groups of Arthropods

Crustaceans

In a crustacean, the first two pairs of appendages are antennae.

First antenna

Second antenna Slide 12 of 42 Copyright Pearson Prentice Hall

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28–2 Groups of Arthropods

Crustaceans

The third pair of appendages are the mandibles. A mandible is a mouthpart adapted for biting and grinding food.

Mandible Slide 13 of 42 Copyright Pearson Prentice Hall

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28–2 Groups of Arthropods

Crustaceans

Decapods have five pairs of legs. In crayfishes, the first pair of legs, called chelipeds, have large claws that catch, pick up, crush, and cut food.

Walking legs Copyright Pearson Prentice Hall

Cheliped

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28–2 Groups of Arthropods

Crustaceans

Behind these legs are four pairs of walking legs.

Walking legs Copyright Pearson Prentice Hall

Cheliped

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28–2 Groups of Arthropods

Crustaceans

Along the abdomen are several pairs of swimmerets, which are flipperlike appendages used for swimming.

Swimmerets

Slide 16 of 42 Copyright Pearson Prentice Hall

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28–2 Groups of Arthropods

Crustaceans

The final abdominal segment is fused with a pair of paddlelike appendages to form a large, flat tail. Tail

Slide 17 of 42 Copyright Pearson Prentice Hall

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28–2 Groups of Arthropods

Spiders and Their Relatives

What are the distinguishing features of spiders and their relatives?

Slide 18 of 42 Copyright Pearson Prentice Hall

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28–2 Groups of Arthropods

Spiders and Their Relatives

Spiders and Their Relatives Horseshoe crabs, spiders, ticks, and scorpions are chelicerates. Chelicerates lack antennae.

Slide 19 of 42 Copyright Pearson Prentice Hall

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28–2 Groups of Arthropods

Spiders and Their Relatives

Chelicerates have mouthparts called chelicerae and two body sections, and nearly all have four pairs of walking legs.

Fanglike chelicera Copyright Pearson Prentice Hall

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28–2 Groups of Arthropods

Spiders and Their Relatives

Chelicerates have two pairs of appendages attached near the mouth that are adapted as mouthparts.

Fanglike chelicera Copyright Pearson Prentice Hall

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28–2 Groups of Arthropods

Spiders and Their Relatives

Chelicerae contain fangs and are used to stab and paralyze prey.

Fanglike chelicera Copyright Pearson Prentice Hall

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28–2 Groups of Arthropods

Spiders and Their Relatives

Pedipalps are longer than the chelicerae and are usually modified to grab prey.

Pedipalp Slide 23 of 42 Copyright Pearson Prentice Hall

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28–2 Groups of Arthropods

Spiders and Their Relatives

Chelicerates are divided into two main classes.

• Merostomata includes horseshoe crabs. • Arachnida, or arachnids, includes spiders, mites, ticks, and scorpions.

Slide 24 of 42 Copyright Pearson Prentice Hall

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28–2 Groups of Arthropods

Spiders and Their Relatives

Horseshoe Crabs Horseshoe crabs first appeared more than 500 million years ago and have changed little since that time. They have chelicerae, five pairs of walking legs, and a long spikelike tail that is used for movement.

Slide 25 of 42 Copyright Pearson Prentice Hall

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28–2 Groups of Arthropods

Spiders and Their Relatives

Spiders Spiders capture and feed on animals ranging from other arthropods to small birds.

Slide 26 of 42 Copyright Pearson Prentice Hall

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28–2 Groups of Arthropods

Spiders and Their Relatives

Some spiders spin webs of a strong, flexible protein called silk, which they use to catch flying prey.

Others stalk and then pounce on their prey. Some spiders lie in wait and leap out to grab insects that venture too near.

Slide 27 of 42 Copyright Pearson Prentice Hall

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28–2 Groups of Arthropods

Spiders and Their Relatives

Spiders do not have jaws for chewing, they must liquefy their food to swallow it.

Once a spider captures its prey, it uses fanglike chelicerae to inject paralyzing venom into it.

Slide 28 of 42 Copyright Pearson Prentice Hall

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28–2 Groups of Arthropods

Spiders and Their Relatives

All spiders produce silk. Spiders spin silk into webs, cocoons for eggs, and wrappings for prey.

Silk glands Copyright Pearson Prentice Hall

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28–2 Groups of Arthropods

Spiders and Their Relatives

They do this by forcing liquid silk through spinnerets, which are organs that contain silk glands.

Spinnerets

Slide 30 of 42

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28–2 Groups of Arthropods

Spiders and Their Relatives

Mites and Ticks Mites and ticks are small arachnids that are often parasitic. Their chelicerae and pedipalps are specialized for digging into a host’s tissues and sucking out blood or plant fluids. Ticks can transmit bacteria that cause serious diseases.

Slide 31 of 42 Copyright Pearson Prentice Hall

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28–2 Groups of Arthropods

Spiders and Their Relatives

Scorpions Scorpions inhabit warm areas around the world. Scorpions have pedipalps that are enlarged into claws. Scorpions chew their prey.

Slide 32 of 42 Copyright Pearson Prentice Hall

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28–2 Groups of Arthropods

Insects and Their Relatives

What are the distinguishing features of insects and their relatives?

Slide 33 of 42 Copyright Pearson Prentice Hall

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28–2 Groups of Arthropods

Insects and Their Relatives

Insects and Their Relatives Centipedes, millipedes, and insects are uniramians. Uniramians have jaws, one pair of antennae, and unbranched appendages.

Slide 34 of 42 Copyright Pearson Prentice Hall

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28–2 Groups of Arthropods

Insects and Their Relatives

Centipedes Centipedes have from a few to more than 100 pairs of legs. Most body segments bear one pair of legs each. Centipedes are carnivores whose mouthparts contain venomous claws that they use to catch and stun or kill their prey.

Slide 35 of 42 Copyright Pearson Prentice Hall

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28–2 Groups of Arthropods

Insects and Their Relatives

Millipedes Millipedes have a highly segmented body. Each millipede segment bears two pairs of legs. Millipedes defend themselves by rolling up into a ball or by secreting unpleasant or toxic chemicals. They feed on dead and decaying plant material.

Slide 36 of 42 Copyright Pearson Prentice Hall

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28–2

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Slide 37 of 42 End Show Copyright Pearson Prentice Hall

28–2

The two main groups of chelicerates are a. spiders and scorpions. b. horseshoe crabs and spiders. c. horseshoe crabs and arachnids.

d. arachnids and insects.

Slide 38 of 42 End Show Copyright Pearson Prentice Hall

28–2

Insects are part of the group a. crustaceans. b. uniramians. c. chelicerates.

d. diplopods.

Slide 39 of 42 End Show Copyright Pearson Prentice Hall

28–2

Most mites and ticks are a. parasites. b. predators. c. herbivores.

d. detritovores.

Slide 40 of 42 End Show Copyright Pearson Prentice Hall

28–2

Which of the following is NOT a typical crustacean characteristic?

a. either two or three body segments b. chewing mouthparts called mandibles c. chelicerae that paralyze prey d. two pairs of antennae

Slide 41 of 42 End Show Copyright Pearson Prentice Hall

28–2

Spiders differ from the other arachnids because they have

a. two major body segments and six legs. b. three major body segments and eight legs. c. two major body segments and eight legs. d. three major body segments and six legs.

Slide 42 of 42 End Show Copyright Pearson Prentice Hall

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