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By Paul Polyplacophora


     Hello, my name is Paul and I m here to tell you about my Class, the Polyplacophora. In the Latin language, poly means many. I have a shell made out of eight separate, but overlapping, plates or valves. You may also know me by my common name, the Chitons.

I only live in the ocean and am generally found clinging tightly onto the rocks in the intertidal zone (the area in the ocean where waves wash in and out and where water from the tidal changes wash in and out of). A few of my Class do live in very deep (more than 5,000 meters) ocean places. The members of my Class range in size from 2 millimeters to 40 centimeters (1/16 inch to 16 inches), and there are about 800 living Species represented in my Class.

By having several valves that can be moved separately, we are able to change the shape of our bodies to fit onto the uneven hard rocky places we like to live on. Our broad, fleshy foot holds us to the rocks so tightly that neither the violent ocean waves nor an enemy can dislodge us easily. You would have to take a sharp object, like a knife, to pry us off our rock and if you did succeed in getting me off, I would curl up into a ball. My hard plates would be on the outside of this ball and my soft vulnerable body parts protected on the inside of the ball.

Most of the members in my class are herbivores (we eat plants). In our mouths is a special mechanism known as a radula. This radula is like a ribbon of tiny hard teeth (think of something very rough like a piece of sandpaper or a fingernail file). By licking the rock with this radula, we rasp off pieces of plant material or algae growing there. We then swallow and digest these food particles.

We breathe in oxygen from the water through six to eighty-eight pairs of gills.

Both the male and females of my class generally release their eggs and sperm directly into the water. When they meet, a new baby polyplacophora is born. However some of the females in my class do keep their eggs inside their body (in the mantle cavity). When they draw in water to breathe, they also draw in the sperm and thus fertilize their eggs. They then give live birth to their young, all ready to fend for themselves in the sea!


Some interesting things about Polyplacophoras:
  • Most polyplacophora are nocturnal, that is, they move around and eat mostly at night.

  • A polyplacophora may spend its entire life in the very small area of a few feet.

  • Polyplacophora often show a "homing behavior". If they get knocked off their rock, they can usually find their way back.


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