Fish Background Information for Teachers and Families

Grade Levels: 3-5, K-3

This page contains information to support educators and families in teaching K-3 students about fish. The information is designed to complement the BrainPOP Jr. movie Fish. It explains the type of content covered in the movie, provides ideas for how teachers and parents can develop related understandings, and suggests how other BrainPOP Jr. resources can be used to scaffold and extend student learning.

Help children understand and explore living things around them. This movie will explore fish and share information about their anatomy and how they are adapted to life underwater. The movie will also explore how fish habitats are changing due to human activities. You may wish to use the Ocean Habitats movie as an extension or review.

Have children brainstorm different types of fish. What do they all have in common? How are they different? Remind children that fish are vertebrates, which means they have a spine, or backbone. Fish are the largest group of vertebrates on Earth. Scientists believe there are over 29,000 different fish species. There are three main groups of fish: jawless fish, bony fish, and cartilaginous fish. Jawless fish, such as sea lampreys and hagfish, have no jaws and instead have funnel-like sucking mouths. Some species bore into the flesh of animals and suck their blood. About 95% of fish are bony fish, which means they have skeletons made of bone. Many fish that children are familiar with are bony fish, including Atlantic salmon, striped bass, bluefin tuna, black marlin, and mackerel. Cartilaginous fish had bodies made of cartilage. Remind children that parts of our ears and noses are made of cartilage. Sharks and rays are cartilaginous fish.

It is important for children to understand the basic characteristics that most fish share. Fish breathe through gills, which are specialized organs that take in dissolved oxygen from the water and push carbon dioxide out. You may want to point out that ocean animals such as whales and dolphins do not have gills, and instead breathe through lungs. Thus, whales and dolphins are mammals and not fish. Many fish are covered with scales, which help protect the animal. Some species, such as clingfish and lampreys, do not have scales. Instead they are covered with a layer of thick mucus, which helps protect the animals from bacterial infections. Like humans, fish have a heart, stomach, intestines, and a brain. But, many species of bony fish have a swim bladder, which gets inflated with air. The swim bladder aids the animals’ buoyancy and movement through the water. Cartilaginous fish do not have swim bladders. Most species of fish have fins—the shape, size, and location of the fins on the animal’s body allows different fish to move in different ways. You may want to research various fish species together and compare and contrast their fins. The tail fin propels the fish forward, while the dorsal fins on the back aid in turning or prevent the fish from rolling. Remind children that fish are cold-blooded animals. They use the environment to help control their body temperatures. Fish may move to warmer or cooler movies to help regulate their temperatures.

Explore different species of fish together and research how they are adapted to life in their habitats. Many small fish, such as mackerel, travel together in large groups called schools. Have children infer why fish might travel with hundreds of other fish. Explain that schools can confuse and distract some predators. Some fish, such as the crocodilefish, use camouflage to stay hidden from predators and prey. Their bodies mimic the color and texture of their surroundings. The flounder stays safe on the ocean floor and both eyes are on the same side of its body to watch for predators above. The stingray has a venomous stinger on its tail to defend itself, and the puffer fish is the second most poisonous animal on the planet, after poison dart frogs. The puffer fish puffs up its body to scare away predators. Some species, such as the porcupinefish, is covered with spines to show predators that they should be left alone. The sailfish is one of the fastest fish in the ocean, reaching speeds over 110 km/h or 70 mph. At high speeds, they pin their large fins to their bodies to make them more streamlined and aerodynamic. To scare off predators, they extend their fins to make them appear larger.

Explain to children that fish have senses of sight, hearing, touch, smell, and taste just like humans. Sharks have very, very sharp senses of smell. Though it’s an exaggeration that a shark can smell just a few drops of blood in the water, sharks are finely tuned to their olfactory senses. Sharks also have a well-developed sense of electroreception and are able to sense the electromagnetic fields that all living things produce. Thus, sharks are adept hunters and able to find prey that are far away or hiding in rocks or in the ocean floor. Scientists believe that sharks use the electrical currents in the water caused by Earth’s magnetic field to help them navigate and orient themselves. Sharks have a reputation for being aggressive hunters and attacking humans, but most sharks would rather leave humans alone.

Help children understand how fish habitats are changing. Fish live in freshwater habitats, like lakes, rivers, and ponds, and they also live in saltwater oceans and among coral reefs. Water pollution and habitat destruction negatively impact many species of fish. Coral reefs are dying at an alarming rate due to higher water temperatures and water pollution. Scientist believe that 10% of the world’s coral reefs are dead, and about 60% of the world’s reefs are at risk of destruction. Many fish use coral reefs to hide or rely on them for a food source. What might happen to fish when they lose their habitats? Have children brainstorm different ideas.

Guide children to understand how people’s actions can affect the lives of fish. Many people around the world rely on fish as a food source, and as a result, overfishing is a problem in many parts of the world. Many fish populations are declining, and some species, such as the bluefin tuna, are threatened. Some species, including the Atlantic cod and many species of shark, have become endangered. Help children understand how living things are connected to each other and rely on each other for survival. What might happen to the food chain if several species of fish became threatened or endangered? You may want to explore the Food Chain movie for an extension.