Questions and Answers
What percentage of animals in the world are invertebrates?
What do invertebrates not have?
What do arthropods have?
What is the largest group of arthropods?
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What do most arthropods have?
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What is the second largest group of invertebrates?
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What do mollusks have?
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Which of the following is NOT a characteristic of invertebrates?
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What is the purpose of an exoskeleton?
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Why do invertebrates often have simple bodies?
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Study Notes
Invertebrate Definition
- Invertebrates make up at least 95% of all animals in the world.
- The common characteristic among all invertebrates is the absence of a backbone.
- Invertebrates have soft, simple, and often small bodies due to the lack of bone support.
- They are also cold-blooded, meaning their body temperature changes with the environment.
Arthropods
- Arthropods have segmented bodies and are the largest group of invertebrates.
- They can live on land (spiders, insects) or in water (crayfish, crabs).
- Insects are the largest group of arthropods and many can fly.
- Arthropods have jointed legs or limbs for easier movement.
- Most arthropods have an exoskeleton, a tough outer skin or shell that protects their body.
Mollusks
- Mollusks have soft bodies and live on land or in water.
- Many mollusks have shells to protect their bodies (snails, oysters, clams, scallops).
- Some mollusks do not have shells (octopus, squid, cuttlefish).
Other Invertebrates
- Coelenterates (jellyfish, sea anemone) have soft bodies and stinging tentacles.
- Echinoderms (starfish, sea urchin) are spiny sea creatures that live only in the ocean.
- Sponges are invertebrates that attach themselves to other things in the water and cannot walk, swim, or fly.
- Annelid worms (earthworms, leeches) are also invertebrates.
- Protozoa and flatworms are invertebrates that are too small to be seen without a microscope.
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Description
Test your knowledge of invertebrates, the animals that make up 95% of the world's species. Learn about their characteristics and features.