In this Grade 7 Life Science lesson from Chapter 12, students explore the defining features of mollusks and echinoderms, learning how structures like the muscular foot, mantle, gills, and lungs function in soft-bodied invertebrates. Students compare the three main mollusk groups — bivalves, gastropods, and cephalopods — examining how each is adapted for movement, feeding, and protection. The lesson builds on prior knowledge of invertebrate body symmetry to help students understand how shell structure and skeletal design relate to animal behavior and survival.
Section 1
Mollusks Use Specialized Feet for Movement
Mollusks have soft bodies and muscular feet that adapt differently across species. Bivalves use feet for burrowing, gastropods glide on foot muscles, and cephalopods have tentacle-like feet for hunting.
Section 2
Echinoderms Deploy Tube Feet to Move and Hunt
Echinoderms use their unique water vascular system to create suction in tube feet. These feet help them travel along the ocean floor and capture prey, like when sea stars pry open bivalve shells.
Section 3
Arthropods Dominate with Jointed Exoskeletons
Arthropods make up three-quarters of all animal species. These invertebrates have segmented bodies protected by hard outer skeletons and include diverse groups like insects, crustaceans, and arachnids.
Section 4
Animals Develop Different Respiratory Systems
Mollusks use gills or lungs with large surface areas to absorb oxygen efficiently. Gills filter oxygen from water in aquatic species, while lungs extract oxygen from air in land-dwelling gastropods.
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Section 1
Mollusks Use Specialized Feet for Movement
Mollusks have soft bodies and muscular feet that adapt differently across species. Bivalves use feet for burrowing, gastropods glide on foot muscles, and cephalopods have tentacle-like feet for hunting.
Section 2
Echinoderms Deploy Tube Feet to Move and Hunt
Echinoderms use their unique water vascular system to create suction in tube feet. These feet help them travel along the ocean floor and capture prey, like when sea stars pry open bivalve shells.
Section 3
Arthropods Dominate with Jointed Exoskeletons
Arthropods make up three-quarters of all animal species. These invertebrates have segmented bodies protected by hard outer skeletons and include diverse groups like insects, crustaceans, and arachnids.
Section 4
Animals Develop Different Respiratory Systems
Mollusks use gills or lungs with large surface areas to absorb oxygen efficiently. Gills filter oxygen from water in aquatic species, while lungs extract oxygen from air in land-dwelling gastropods.
Book overview
Jump across lessons in the current chapter without opening the full course modal.
Continue this chapter