Is the familiar rocky shore organism known as the limpet just a bit misunderstood?
LOUISE B. FIRTH of the School of Biological and Marine Sciences, University of Plymouth, has written a paper delving into the provisioning and cultural services of the limpet.
Read some extracts below:
Louise writes: "My research career started with studying the ecology of limpets. On telling people about my project, many reminisced about kicking them off the rocks as children and laughed about having to get them first time or they would clamp down. Some did not even realise that they were animals. One person even expressed wonder about why on Earth I would spend three years working on such ‘boring animals’.
In comparison to other molluscs (e.g. oysters, mussels and cowries), which are renowned for their gastronomic, economic or aesthetic value, the ‘drab’ limpet does not win any prizes, and in many regions is commonly considered ‘poor food’ and even ‘famine food’. I felt that it was high time that someone ‘flew the flag’ for limpets! My comprehensive review attests to the important role that limpets played in past and present coastal cultural heritage and food culture.
Through integrating the fields of ecology, anthropology, history and social science, I endeavoured to celebrate the past and present importance of the limpet for humans globally, framed in an ecosystem services context. Ecosystem services are considered the ‘benefits that people derive from ecosystems’ and are generally classed into four major categories that are underpinned by the species within ecosystems. Provisioning services provide food, medicinal resources and raw materials. Regulating services are the services that ecosystems provide by acting as regulators such as carbon sequestration, erosion and pest control. Cultural services are usually defined as the intangible and non-material benefits ecosystems provide and include aesthetics and inspiration, cultural heritage, spiritual and religious values, knowledge and education, and recreation and tourism. Supporting services include biodiversity and processes such as soil formation, primary production and habitat provision.
This review focuses on coastal groups and typically features true limpets (Patellidae) and keyhole limpets (Fissurellidae) but other groups occasionally feature. Whilst the scope of the review is the global coastline, many of the case studies and examples are drawn from temperate systems or in developed countries, reflecting the distribution of published research. I focus on the provisioning and cultural services only, because they are more directly related to human uses than regulating and supporting services.
Limpets are one of the most abundant and familiar rocky shore organisms globally. They are perhaps most famous for their ability to cling onto rocks, making them synonymous in our culture with tenacity, but they are also well known for their grazing activity, which has an important structuring function. In contrast to other molluscs, such as oysters and mussels, which are celebrated for their gastronomic and cultural importance, little is known about the provisioning and cultural services of the humble limpet.
Not only were limpets often the dominant shellfish eaten by early modern humans, but they also sustained the poor during times of famine and destitution. Limpets were exploited for food by early hominids, including Neanderthals, from the Palaeolithic period. It is generally considered that a switch to a seafood diet led to the evolution of the large, complex, metabolically expensive brain characterised by modern Homo sapiens.
Today, limpets are considered a delicacy in many cultures. They are popular as bait and their shells have a wide variety of uses, including tools, currency, offerings, traditional medicine, jewellery and artworks. The ‘teeth’ of limpets are known to be composed of goethite—the strongest material known in nature. In Hawai‘i, the shells were used for scraping the skin off taro plants and sweet potatoes and for grating coconut meat, and particular species were used as drinking vessels and for dispensing different volumes of traditional medicine. Limpet shells were used by nursing mothers as nipple shields in a practice thought to date back to the Vikings. As for modern medicinal value, the Californian giant keyhole limpet (Megathura crenulata, Sowerby 1825), contains a substance that is used increasingly in immunotoxicological studies, including the treatment of bladder cancer, atopy and asthma and autoimmune diseases such as Lupus. They also have important spiritual and religious relevance, featuring in myriad traditions, superstitions and folklore. Shells were used to collect and drink water from holy wells to relieve illness in Wales and Ireland. Limpets are commonly found in burial sites - in the Channel Islands and Brittany, shells have been found in huge abundance in cromlechs (subterranean burial chambers).
Due to the availability of historical data, at least two species of limpet are officially listed as extinct on the International Union for Conservation of Nature (IUCN) Red List: one due to habitat loss (Lottia alveus Conrad 1831), the other to coastal development (Lottia edmitchelli Lipps 1963). Two other species with very narrow niches (Siphonaria compressa Allanson 1958), which lives on seagrass in South African lagoons, and Ancylastrum cumingianus Bourguignat 1853, which lives in Tasmanian freshwater lakes) are currently listed as critically endangered. Whilst neither Patella ferruginea nor Scutellastra mexicana (rocky shore species that occur in the Mediterranean and the eastern Pacific, respectively) are listed, it is argued by some that they are on the brink of extinction, primarily due to over-exploitation.
Whilst limpets are not exploited on a global scale, there are many regions where populations are vulnerable to over-exploitation and possible extinction. Appropriate management is required if we are to protect these underappreciated animals.
You can read the full text here as published in International Review of Environmental History, Volume 7, Issue 2, 2021, edited by James Beattie, published 2021 by ANU Press, The Australian National University, Canberra, Australia.
Click below to download Louise's 'Limpets in our Lives' Comic Strip