Invertebrates Biology Quiz

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.

Test your knowledge of invertebrates, the animals that make up 95% of the world's species. Learn about their characteristics and features.