What Is the Floor of an Aquatic Biome Called? — Reading Comprehension

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Grades

Standards

MS-LS1-4

About This Reader

This NGSS-aligned science reading passage explains the benthic zone, which is the floor of an aquatic biome such as oceans, lakes, and rivers. Designed for middle school students, the passage describes how the benthic zone varies with depth and what kinds of organisms live there. Students will learn about benthic organisms (benthos), marine snow, and how these organisms help recycle nutrients and support ecosystem health. The passage introduces vocabulary like seagrass, pressure, and sediment, and explains how life can survive even in deep, dark environments. It connects to NGSS standard MS-LS2-1 by helping students understand how energy and matter move through ecosystems, especially in underwater environments. This reading supports comprehension in life science, ecosystem dynamics, and environmental study.

CONTENT PREVIEW

The floor of an aquatic biome is called the benthic zone. This zone includes the bottom surface of oceans, lakes, rivers, and other bodies of water. It stretches from shallow coastal areas to the deepest parts of the ocean floor. The benthic zone plays an important role in aquatic ecosystems because it supports many organisms and helps recycle nutrients.

The benthic zone varies depending on its depth and location. In shallow waters, it receives sunlight, allowing plants like seagrasses and algae to grow. These plants provide food and shelter for small fish, crabs, and snails. In deeper waters, where sunlight ca

nnot reach, the benthic zone is cold, dark, and high in pressure. Here, strange creatures like sea cucumbers, giant tube worms, and deep-sea fish live. These organisms often rely on dead matter, called marine snow, that sinks down from above.

The benthic zone is home to benthic organisms, also known as benthos. These include both plants and animals that live on or in the bottom sediments. Some benthos crawl or swim just above the floor, while others burrow into the mud or attach to rocks. They are essential to the health of aquatic ecosystems because they help break down dead plants and animals, recycling nutrients back into the environment.

In real life, the benthic zone is also important for humans. Many people depend on bottom-dwelling fish and shellfish for food. Scientists study the benthic zone to learn about pollution, climate change, and the health of aquatic habitats.

Fun Fact: The benthic zone in the Mariana Trench is so deep that the pressure is over 1,000 times greater than at sea level—yet life still exists there!

What is the floor of an aquatic biome called?

Surface zonePelagic zoneBenthic zoneTidal zone

What can be found in the benthic zone of shallow water?

IcebergsCoral and seagrassFlying fishFloating algae

What is marine snow?

Real snow underwaterBits of dead matter that sinkA type of saltOcean foam

Which animals are benthic organisms?

Birds and frogsWhales and sharksCrabs and sea cucumbersDolphins and jellyfish

How do benthic organisms help aquatic ecosystems?

By eating each otherBy causing pollutionBy recycling nutrientsBy blocking sunlight

Why is the deep benthic zone different from shallow areas?

It has more lightIt has more sandIt has no waterIt is dark and high-pressure