Section 1
Water Separates Into Distinct Ecosystems
Earth's water divides into freshwater (3%) and saltwater (97%) ecosystems. Each ecosystem supports different organisms based on salt content, light penetration, and oxygen availability.
In this Grade 5 lesson from Science: A Closer Look, Chapter 3, students learn how water ecosystems are organized into freshwater, saltwater, and mixed-water environments and how organisms within them are classified as plankton, nekton, or benthos. Students also explore how abiotic factors such as dissolved salt, sunlight, and dissolved oxygen determine which organisms can survive in a given water ecosystem. The lesson includes a hands-on inquiry activity modeling how ocean water becomes salty as fresh water flows across land.
Section 1
Water Separates Into Distinct Ecosystems
Earth's water divides into freshwater (3%) and saltwater (97%) ecosystems. Each ecosystem supports different organisms based on salt content, light penetration, and oxygen availability.
Section 2
Organisms Adapt to Specific Water Zones
Living things in water fall into three categories: plankton (drifters), nekton (swimmers like fish and whales), and benthos (bottom-dwellers). Each group has developed special adaptations for survival.
Section 3
Oceans Separate Into Distinct Zones
Oceans divide into intertidal (shoreline), neritic (shallow, sunlit), bathyal (middle depth), and abyssal (deep, dark) zones. The amount of light determines which organisms can survive in each zone.
Section 4
Estuaries Connect Fresh and Salt Waters
Estuaries form where rivers meet oceans, creating unique ecosystems with varying salinity. Salt marshes within estuaries filter pollution, absorb storm water, and provide nurseries for many young aquatic organisms.
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Section 1
Water Separates Into Distinct Ecosystems
Earth's water divides into freshwater (3%) and saltwater (97%) ecosystems. Each ecosystem supports different organisms based on salt content, light penetration, and oxygen availability.
Section 2
Organisms Adapt to Specific Water Zones
Living things in water fall into three categories: plankton (drifters), nekton (swimmers like fish and whales), and benthos (bottom-dwellers). Each group has developed special adaptations for survival.
Section 3
Oceans Separate Into Distinct Zones
Oceans divide into intertidal (shoreline), neritic (shallow, sunlit), bathyal (middle depth), and abyssal (deep, dark) zones. The amount of light determines which organisms can survive in each zone.
Section 4
Estuaries Connect Fresh and Salt Waters
Estuaries form where rivers meet oceans, creating unique ecosystems with varying salinity. Salt marshes within estuaries filter pollution, absorb storm water, and provide nurseries for many young aquatic organisms.
Book overview
Jump across lessons in the current chapter without opening the full course modal.
Continue this chapter