In this Grade 7 Life Science lesson from Chapter 12, students explore the body plans of cnidarians and worms, learning how structures like tentacles, nematocysts, and nerve nets enable cnidarians to capture prey and respond to their environment. The lesson covers key concepts including tissue organization, simple muscle and nervous systems, body symmetry, and how body shape affects movement in worms. Part of a broader unit on invertebrate animals, it builds foundational knowledge of how body systems support survival in animals without backbones.
Section 1
Cnidarians Capture Prey with Specialized Stinging Cells
Cnidarians use tentacles with nematocysts to capture food and protect themselves. When prey touches a stinging cell, a barbed filament releases, sometimes injecting poison to immobilize prey.
Section 2
Body Symmetry Shapes How Animals Feed and Move
Animals with radial symmetry can capture food from any direction but change direction with difficulty. Bilateral animals have a head-end and move forward, processing food as it travels through their body.
Section 3
Earthworms Process Soil Through Complex Systems
Segmented worms like earthworms have developed body systems including digestive, excretory, muscular, and nervous systems. They consume soil, extract nutrients from decaying matter, and excrete materials that enrich soil.
Section 4
Worms Respond to Environmental Stimuli Without Eyes
Though lacking eyes, worms gather environmental information through their skin and nervous system. They react to stimuli like moisture, texture, vibrations, and light to find suitable habitats and avoid danger.
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Section 1
Cnidarians Capture Prey with Specialized Stinging Cells
Cnidarians use tentacles with nematocysts to capture food and protect themselves. When prey touches a stinging cell, a barbed filament releases, sometimes injecting poison to immobilize prey.
Section 2
Body Symmetry Shapes How Animals Feed and Move
Animals with radial symmetry can capture food from any direction but change direction with difficulty. Bilateral animals have a head-end and move forward, processing food as it travels through their body.
Section 3
Earthworms Process Soil Through Complex Systems
Segmented worms like earthworms have developed body systems including digestive, excretory, muscular, and nervous systems. They consume soil, extract nutrients from decaying matter, and excrete materials that enrich soil.
Section 4
Worms Respond to Environmental Stimuli Without Eyes
Though lacking eyes, worms gather environmental information through their skin and nervous system. They react to stimuli like moisture, texture, vibrations, and light to find suitable habitats and avoid danger.
Book overview
Jump across lessons in the current chapter without opening the full course modal.
Continue this chapter