What are Chitons?
Chitons are mollusks in the class Polyplacophora, distinguished by their characteristic shells, which consist of eight overlapping plates. The creatures are widely found around the world, and fossil evidence suggests that they have been around for quite a long time. If you're interested in seeing some chitons for yourself, tidepooling is an excellent way to spot the unique animals, as they tend to favor the intertidal zone. Chitons may also be found in deeper water in some cases, but they exclusively marine, so they will never be found in freshwater.
Like other mollusks, a large part of a chiton's body is a large, muscular foot, surrounded by gills and a protective mantle. The animals pull themselves along rocks with their feet, scraping the rocks from algae and other forms of nutrition. A chiton is roughly oblong in shape, and the animals can be very hard to spot, since many have protective coloration which helps them blend in with the rocks. Others are radiant and very colorful; the creatures come in a wide range of colors and sizes.
In some regions of the world, chitons are known by other alternate names, such as loricates, coat of mail shells, and sea cradles. Some biologists also refer to them as polyplacaphorans, in a reference to their classification, which in turn refers to the multiple plates of their shell structures. When removed from their rocky substrate, chitons will curl up to protect their tender undersides until they bump into another rock to call home. This defense also makes the animals a less appealing source of potential food.
One unique variety of chiton, the gumboot chiton, is covered in a leathery layer of red skin. This layer obscures the shapes of the individual plates, and makes the animal difficult to differentiate from the colorful algae that line the rocky pools it prefers. Gumboot chitons can also get quite large, and often grow to sizes much larger than an average human hand. The animals once provided a source of food to Native Americans in the Northwest, thanks to their size.
Hundreds of individual species in a plethora of genera are classified as chitons. An assortment of marine animals prey on chitons, including starfish. Starfish pry the animals from the rock, using their assortment of tube feet to keep the chiton from curling up. Crabs, fish, and sometimes seagulls will eat chitons as well, in addition to sea anemones.
@StarJo - I live near a rocky beach, and I have seen plenty of gumboot chitons, both in the spring and after big storms. Though they look like they might be fragile because they are fuzzy, they are actually pretty well adapted, tough creatures.
For one thing, they survive getting knocked around a lot by strong waves. Since they lose their grip easily, they have to endure getting tossed about and even beached at times. Their ability to breathe oxygen saves them from certain death.
Getting tossed around can be hard on the shell plates. Gumboot chitons frequently get their shells broken, but they have the ability to repair the breaks.
I went to an awesome aquarium that had gumboot chitons, and I actually got to touch one. It felt very fuzzy! I learned from the tour guide that its brick-red color is due to its diet of red algae. It uses its radula lined with teeth to scrape up the algae, and its teeth have so much magnetite in them that they can be picked up by magnets.
Gumboot chitons can’t cling as tightly to rocks as other chitons, so they get washed up on the beach during storms. In spring, they gather on rocky beaches to spawn. At low tide, they are exposed and can actually breathe oxygen!
I went with my church youth group as a chaperone on their trip to the ocean. We went to an aquarium while we were there, and we learned about many marine creatures, including the chiton, from the guide.
We learned that chitons can develop a certain type of eyes on their dorsal side that allows them to distinguish light from shadow. This way, they don’t have to remove their girdle from a rock to look up.
Some varieties of chiton find a place and call it home. They will roam at night in search of food, but they will return home during the day.
We also learned that some species of chiton are carnivorous. They have a bigger girdle than other chitons, and they use it to catch small fish and crustaceans. They hold the girdle up off of the surface above the prey, and then they clamp it down on them to feed.
I saw a chiton while at the beach with my family. To me, it looked like a turtle with its brown shell, and it was well camouflaged on top of the rock.
My brother-in-law is a marine biologist, and he spotted one of them curled up and not attached to anything. He pulled it out of the water and showed me its underside.
The creepiest thing about the chiton was its mouth. It looked like the mouth of a leech. Since it doesn’t have a nose and eyes right above the mouth, it looks strange and scary there all alone.
What do Chitons have to stop terrestrial predators from attacking them?
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