Crab Facts: Lesson for Kids

Instructor: Lauren Scott

Lauren has a Master's degree in special education and has taught for more than 10 years.

This lesson will introduce you to the the most famous pinchers of the land and sea- crabs! You will learn about their body structure, their diets, and how they move and grow.

What is a Crab?

Crabs are animals that live in water. They are invertebrates, meaning they have no backbone. All crabs are covered by hard shells that protect their internal organs. Their gills, which they use to pull oxygen from the water, are hidden inside their shells. Crabs are related to insects and spiders, but they have more legs than their creepy-crawly cousins. Crabs have ten legs, including their walking legs and their claws. Those claws can deliver a sharp pinch to any animal or person who bothers a crab! Some crabs also have two paddle-shaped legs that help them swim.

Crabs use their large front claws for self defense.
crab on beach

There are thousands of different species, or kinds, of crabs. They range in size from less than an inch to over 10 feet across. Crabs may be all sorts of colors, including red, green, brown, and blue. Some have smooth shells, while others have lumps and bumps.

Crab Habitats

Crabs can live in just about any body of water, including salt water and fresh water, and some can survive on land. You may see them scuttling sideways over a sandy beach, by a muddy lake, or along a rocky sea cliff. They can live in water that is warm or icy, deep or shallow. They tend to stay on the bottom, but some crabs can also swim. Many crabs migrate, meaning they move from one place to another during the year.

Eating and Being Eaten

Crabs aren't picky eaters. They will eat just about anything they stumble upon, including algae, clams, other crabs, and dead animals. Their claws help them break open shells and tear off small pieces of food.

Birds will pluck crabs out of the water or off the ground.
seagull with crab

Crabs are a food source for lots of other animals. Fish will eat young crabs, and animals with sharp teeth or beaks can eat the adults. Octopuses, sea birds, and many fish dine on crabs.

Life Cycle

Female crabs carry thousands, even millions, of eggs underneath their bodies. When the eggs hatch, the tiny babies drift into the water. They don't look like adult crabs yet. Baby crabs go through a few changes before they start to look like adults.

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