Cephalopods, Crustaceans, & Other Shellfish
Temperate Eastern Atlantic Ocean Along the Coast of Western Europe
Class Gastropoda (snails and slugs), Family Patellidae (true limpets)
The common limpet is an herbivorous marine snail that lives along the rocky shores of Western Europe. As they live in the intertidal zone (the area along the shore between the high tide and low tide sea levels), these limpets are extremely well adapted to an amphibious life. The thick, conical shell and strong, muscular foot combine to offer the common limpet a formidable defense against predators both in and out of the water. Large crabs and sea stars are potential predators underwater and birds are a primary threat above. However, the shell is shaped in such a way that it is difficult to grasp and it is thick enough to be difficult to break. It also perfectly covers the entire soft part of the body.
Using its muscular foot, the common limpet is able to form such a tight bond to its home rocks that it is very difficult to pry off. In addition to protection from predation, the shape of the shell and strength with which it can adhere to the rocks serve two additional purposes for the common limpet. The shell is shaped to give this animal a low profile, protecting it from crashing waves and strong coastal currents. It would be unable to succeed if it could not remain in its preferred habitat. Furthermore, during low tides, the tight seal that the common limpet creates with its rock prevents it from drying out in the sun.
Common limpets are herbivorous, but they likely also eat young barnacles and other things that settle on their home rocks. They scrape the rock’s surface with a strong, toothy organ called a radula. It is very difficult for sedentary animals or plants to become established in a common limpets territory because it scrapes its rocks clean in a relatively short period of time. Common limpets reproduce through a behavior known as broadcast spawning, where several females release eggs and several males release sperm into the water at the same time. This method increases the likelihood that eggs will become successfully fertilized and that fertilized eggs will not be eaten by nearshore egg predators. This species is also known to undergo male to female sex change. All small individuals are male, and upon reaching a certain size, they change to become female. Sex change is a common phenomenon among limpets and other groups of marine animals.
Though they are not very large (no more than a few inches long), common limpets are eaten by people throughout their range. Living in the intertidal, they are easy to locate during low tide. They are difficult to pry off of their rocks, even for people, but given the right tools, a collector can remove all of the limpets from an area. Their population trends are unknown, but they have likely been depleted in some areas where numerous people hunt.
Fun Facts About Common Limpets
1. Common limpets grow to a maximum length of 2.4 inches (6 cm), with females typically growing larger than males.
2. Common limpets living under algae live only 2 to 3 years, whereas those living on bare rocks may live up to 16 years.
3. Common limpets move around during the first few years of life, then settle in one home for the remainder of their lives.
4. Common limpets return home after feeding to the same spot in their rock that’s been worn down by abrasion from their bodies.
5. Common limpets typically aren’t active until they’re submerged underwater where it’s easier to move on mucus.1
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