Simple Animals: Arthropods Around Us

Arthropods, including millipedes and spiders, are a diverse group of invertebrates with over a million known species. Despite their differences, they share common features such as a hard exoskeleton and segmented bodies. Many arthropods have jointed appendages, like the hinged claw of a crab. These creatures are not only diverse but also beneficial to humans in various ways.

Which of the following groups do millipedes and spiders belong to?

• Annelida

• Cnidaria

• Arthropoda

• Mollusca

Approximately how many known species of arthropods are there?

• 1 million

• 2 million

• 500,000

• 10 million

What is the hard outer shell of arthropods called?

• Mesoskeleton

• Exoskeleton

• Endoskeleton

• Hydroskeleton

Which of the following is NOT a segment of an insect's body?

• Head

• Thorax

• Abdomen

• Tail

What feature of arthropods allows for movement in their appendages?

• Fixed joints

• Flexible joints

• Hinged joints

• Rigid joints