Original file (SVG file, nominally 512 × 281 pixels, file size: 131 KB)
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Summary
| Description |
English: This is a cross section of a normal sea urchin. The cross section is not symmetrical to show the five point radial symmetry.
The genital plates surround the anus on the aboral surface of the sea urchin. Each genital plate contains a single gonopore connected to a corresponding gonad. A number of hard plates also surround the anus. One of the hard plates contains the madreporite. The axial gland pulsates to move fluid around the inside of the body. Sea urchins have five gonads, which are their reproductive organs. Digestion of food occurs in the intestine. The ampullae branch from each side of the radial canals and become the tube feet when they are outside of the test. The test is the shell of the sea urchin and is made of fused plates of calcium carbonate. The radial canals are part of the water vascular system. The esophagus is at the top of the Aristotle’s lantern and is involved in food digestion. Aristotle’s lantern is the chewing mechanism above the mouth. The mouth consists of five calcium carbonate teeth. The nerve ring encircles the mouth and is located inside Aristotle’s lantern. The ring canal is also located inside Aristotle’s lantern. The test plates are the fused plates of calcium carbonate the make up the test. The tube feet are part of the water vascular system and enable the sea urchin to move. The spines are along the outside of the sea urchin to protect it from predators. |
| Date | |
| Source | Own work |
| Author | Erinlandry |
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File history
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 00:08, 27 May 2014 | | 512 × 281 (131 KB) | Erinlandry | User created page with UploadWizard |
