The Kids' Page: Limpets - the strongest teeth in the world.

April, 2015





Plate limpets attached to a rock in the tidal zone at Palmer’s Point in Patrick’s Point State Park. Photo: kara brugman, CC.  Do you know what the strongest natural material in the world is?  Spider silk is a good guess.  It was the strongest material found until recently.  Now we know that limpet teeth are the strongest natural material in the world!

What is a Limpet? Limpets are an aquatic type of mollusk related to snails.  Limpets are sometimes called sea snails.  Limpets are found in freshwater, but mostly in salt water.  There are many species on the North Coast.  They live on rocks along the coast right in the tide zone.  They have a “foot” like a snail and a shell.  The shell is shaped like a witches hat with some being more pointy than others.

Professor Asa Barber led the study on limpet teeth and their strength.  She said their strength is like “a piece of spaghetti enduring the force of 3,000 bags of sugar.”  Limpet teeth are 10 times stronger than human teeth and 5 times stronger than bamboo.  What gives limpet teeth such strength is a material called goethite, which is a hard material that forms in the teeth as they grow. 

There are hundreds of species and they can be found all over the world in rocky coastal areas.  Limpets can live up to 20 years and can range in size from the width of a pencil up to 8 inches. They scrape algae and diatoms off the rock with their radula (tiny rows of teeth that are used by mollusks for scraping food). They also use their radula to scrape off rock to make the perfect fit for their shell on their “home site.”   If it’s a very hard rock, their shell will grow to fit that home site.  They are very protective over their home site and will push others away to defend their perfect spot. 

During low tide at night is when they prefer to move around and eat.  This is when it’s least likely to get eaten by birds, seals, or fish.  They keep cool and moist during the day by trapping water under their shell.  Limpets are able to follow their slime trail back to their home site, and their slime helps grow more algae for them to eat.  They attach themselves onto the rock so hard it is very hard to remove them, and it can harm the limpet if you try. 

Living in the tide zone on a rock is a tough life with all those waves crashing against you and sometimes being under water and sometimes being above water.  Limpets do a very good job at surviving their environment, and having the strongest teeth certainly helps.

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