Sea Urchin Anatomy & Dissection Lab
This lab saves your progress automatically on this device. About 35 minutes.
Sea Urchins: Spiny Grazers of the Sea
Sea urchins are echinoderms — a group of spiny-skinned marine animals that also includes sea stars and sand dollars. They live in oceans all over the world. In the cold waters around Long Island, the green sea urchin clings to rocks and pilings in Long Island Sound and along the Atlantic shore.
A sea urchin's round body is covered in movable spines. These spines protect the urchin from predators and help it slowly move and wedge into cracks. Underneath the spines is a hard internal skeleton called the test, made of fused plates of calcium carbonate. When an urchin dies, the spines fall off and this round test is what often washes up on the beach.
Sea urchins move and feed using hundreds of tiny tube feet, also called podia. The tube feet are part of the water vascular system, a network of water-filled canals. By pumping water in and out, the urchin extends and grips with its tube feet.
On the underside (the oral side) is the mouth. Inside the mouth is a complex five-toothed jaw called Aristotle's lantern, which scrapes algae and kelp off rocks. Sea urchins are herbivores. When their numbers grow too large, they can overgraze a kelp forest and create a bare zone called an urchin barren.
The orange parts inside an urchin are the gonads, its reproductive organs. People harvest these as a seafood delicacy called uni.
Answer the questions below in complete sentences.
Key Vocabulary
Tap a card to flip it. It stays open for 8 seconds, then closes. Only one card opens at a time — you can reopen any card as many times as you like.
Matching Practice
Click a term on the left, then click its matching definition on the right. Correct matches turn green.
Term
Definition
Click Each Marker to Explore
Tap the glowing dots on the outside (left) and inside (right) of the urchin. Read about each structure before you label it in Part 4.
Outside (whole urchin)
Inside (dissected)
Identify the Structures
Click a numbered box on the diagram, then click the correct word from the bank below. Click a box again to clear it. Then press Check My Labels.
Structure & Function Data Table
Complete every box: tell where each structure is found and what its function (job) is. A completed table is worth 4 points.
| Structure | Where it is found | Function (its job) |
|---|---|---|
| Spines | ||
| Test | ||
| Tube feet (podia) | ||
| Aristotle's lantern | ||
| Gonads |
Reading a Graph: Urchins & Kelp
Scientists counted sea urchins and measured kelp cover at five sites. Study the graph, then answer the questions below it.
Use the graph to answer the questions below.
Final Quiz
Answer all questions. Each is worth 1 point (5 total). Read carefully — this is written in Regents style.
