Science Worksheet · Grades 6–8
Sea Jellies Worksheet
A printable science worksheet for grades 6-8 on sea jellies. Students read a one-page passage on the phylum Cnidaria — radial symmetry, a nerve net instead of a brain, the three body layers, the nematocyst that fires like a harpoon, and the two-stage life cycle — then answer four multiple-choice questions, six true-or-false statements, and six fill-ins. A complete answer key is included.
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Subject
Science
Grades
Grades 6–8
Skill Focus
Sea Jellies, life science
Lesson Length
40 minutes
Learning Objective
Students will describe the anatomy, stinging mechanism and two-stage life cycle of a sea jelly, and distinguish venomous from poisonous.
Lesson Overview
About this worksheet
Marine biologists call them sea jellies rather than jellyfish for a simple reason: they are not fish. They belong to the phylum Cnidaria along with the corals, hydras and sea anemones — relatives that spend their adult lives fastened to a rock, while sea jellies drift or swim.
The worksheet is organized around what a sea jelly manages to do without the equipment you would expect it to need. It has no brain, only a simple net of nerves. It has radial symmetry, with body parts arranged in a circle around a center point rather than in two matching halves, which means it senses food and danger in every direction at once. Its digestive system has a single opening that serves as both mouth and exit. Some species are less than five percent solid material, which is why light passes straight through them.
One distinction is a vocabulary lesson in itself: a stinging sea jelly is venomous, not poisonous. Something poisonous harms you if you eat or handle it; something venomous injects a toxin into you. A sea jelly fires a coiled capsule called a nematocyst like a microscopic harpoon, driving a barbed thread into whatever touched it. That distinction is one of the fill-in items.
The passage also separates the Portuguese man-of-war from the sea jellies, where it is usually filed by mistake — it is a cnidarian, but it is a floating colony of many small organisms rather than a single animal. Page 2 asks sixteen questions in three forms; page 3 is a complete answer key with a short reason beside every false statement.
How to Use This Lesson
Read the passage on page 1.
Answer the four multiple-choice questions in Section A.
Mark each Section B statement TRUE or FALSE, and be ready to say why.
Write the missing word in each Section C sentence.
Use the answer key on page 3 for self-check or grading.
Discuss the difference between a venomous animal and a poisonous one, with examples of each.
Printable Resource
A classroom-ready PDF with everything in one printable resource.
Free Member Resource · Printable PDF · 3 pages · Answer Key
Sea Jellies Worksheet
A printable science worksheet for grades 6-8 on sea jellies. Students read a one-page passage on the phylum Cnidaria — radial symmetry, a nerve net instead of a brain, the three body layers, the nematocyst that fires like a harpoon, and the two-stage life cycle — then answer four multiple-choice questions, six true-or-false statements, and six fill-ins. A complete answer key is included.
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