Chapter 3.25
3.25.Giant pacific chiton (Cryptochiton stelleri)
Elizabeth Kenopic , University of Guelph, Canada
Suggested citation for this chapter.
Kenopic,E. (2022) Fish And Freshwater/Marine Invertebrates. In The Student Encyclopedia of Canadian Indigenous Foods. Editor, M.N. Raizada, University of Guelph, Canada. http://www.firstnationsfoods.org/
Introduction
Cryptochiton stelleri, also known as Giant Pacific chiton, are a species of mollusk native to the Northeast Pacific Ocean (Lord, 2011b; Shwabe, 2010). They have traditionally been used as a food source for a variety of Indigenous peoples. This paper will explore the characteristics of its species, its history with Indigenous peoples, as well as its commercial potential as a marketed food product.
Species Information
Giant Pacific chiton belong to the phylum Mollusca, a phylum which also includes (but is not limited to) clams, scallops, oysters, cuttlefish, snails, and slugs (Campbell & Dawes, 2015; Shwabe, 2010). There are estimated to be around 1000 species of chiton worldwide (Campbell & Dawes, 2015). Chiton physiology is known for three key features: the mantle cavity, dorsal plates, and the radula (Campbell & Dawes, 2015).
The mantle cavity is a versatile feature that houses the gills, mucus secreting glands, anus, and reproductive organs (Campbell & Dawes, 2015). As such, it is essential for respiratory function, the formation of the dorsal plates, elimination, and reproduction. In many species of chiton, the mantle cavity is partially or fully hidden from view by the eight dorsal plates, which are characteristic of all chiton (Shwabe, 2010). In the Giant Pacific chiton, however, the dorsal plates are covered by the mantle, which is a red-brown colour with a yellow floor (Kuhnlein & Humphries, 2017). The dorsal plates are another defining feature of chiton. The eight plates have different terms depending on their position (Shwabe, 2010). The first plate is denoted by the roman numeral I and called the head valve and the last plate is denoted by the roman numeral VIII and called the tail valve. Any plates in between are referred to as the intermediate valves. The appearance and texture of dorsal plates are important in distinguishing one species of chiton from another (Shwabe, 2010). The visibility of the plates can also be used to identify species, such as the Giant Pacific chiton, where dorsal plates are covered by the mantle (Kuhnlein & Humphries, 2017).
The radula is a toothed tongue used to scrape algae, the main food source of Giant Pacific chiton, from rocks (Brooker & Shaw, 2012; Campbell & Dawes, 2015). When the oldest teeth, which reside on the end of the radula, become dull, they separate from the radula and a new row of teeth is grown (Campbell & Dawes, 2015). Herbivores such as the Giant Pacific chiton tend to have wide radula with many tiny teeth, while carnivorous chiton have the opposite (Campbell & Dawes, 2015).
It is important to mention that Giant Pacific chiton are known for their tremendous size compared to other chiton species. Most species of chiton rarely exceed 3 centimeters long, while Giant Pacific chiton can easily exceed 35 centimeters in length and 2 kilograms in weight (Campbell & Dawes, 2015; Kuhnlein & Humphries, 2017).
Geographical Background
Giant Pacific chiton are an aquatic species that reside along the North American Pacific coast, from California all the way to Alaska (Campbell & Dawes, 2015; Lord, 2011b). They use their foot to suction themselves to rocks close to shore, though they have been found in waters up to 60 meters deep (Campbell & Dawes, 2015; Lord, 2011b). Studies have shown that smaller Giant Pacific chiton tend to prefer more sheltered areas, with less intense wave activity and a lower threat of predators, such as urchin pits (Lord, 2011a).
Associated Indigenous Peoples
Since Giant Pacific chiton are found along the North American Pacific coast, the many Indigenous groups that inhabited these regions often utilized them as a food source. These groups include (but are not limited to) the Tlingit, Kwakiutl (Kwakwaka'wakw), Manhousat, and Tsimshian peoples (Kuhnlein & Humphries, 2017). The Nootka, Coast Salish, and Nuxalk peoples also consumed Giant Pacific chiton, but on a much smaller scale and more irregularly than other groups. Groups from Southern Alaska, such as the Aleut and Alutiiq peoples, also harvested and ate Giant Pacific chiton. Most Indigenous groups used chiton as a food source, though some also believed in its medicinal benefits. For example, Kyuquot used boiled chiton to alleviate arthritis pain (Kuhnlein & Humphries, 2017). See sections “Harvest” and “Processing & Preparation” to learn how Giant Pacific chiton were collected and served by various Indigenous groups.
Harvest
Giant Pacific chiton were accessible year-round so long as the tide was low, meaning they were a reliable and steady food source for many Indigenous groups (Kuhnlein & Humphries, 2017). However, certain groups avoided collecting chiton depending on the time of year or the method of collection. The Nootka peoples withheld from chiton consumption during summer months and March due to the risk of being affected by poison tides and the off-putting taste caused by herring spawning, respectively. Tlingit peoples also avoided collecting chiton during the summer. The Kyuquot peoples would not collect chiton if they were not found on rocks or attached to other sea creatures they gathered (Kuhnlein & Humphries, 2017).
The actual process of harvesting chiton was fairly similar between different Indigenous groups. Historically, chiton was collected by women and then placed into a basket or net for transport (Kuhnlein & Humphries, 2017). A chiton’s muscular foot allows them to adhere themselves very firmly to rocks and other hard surfaces (Campbell & Dawes, 2015). This made them particularly difficult to remove, so Indigenous peoples often used instruments to aid in prying them off (Kuhnlein & Humphries, 2017). These instruments varied between groups. Tsimshian women traditionally removed chiton from rocks using prying sticks built from knives, sharp rocks, or yew. In recent times, Tsimshian peoples utilized a knife as well as a pronged fork to detach them. Nootka peoples were reported to have used a sharp spear, and chiton hiding under rocks were removed by Kwakiutl peoples using a digging stick (Kuhnlein & Humphries, 2017).
Processing & Preparation
Giant Pacific chiton could be simmered, steamed, eaten fresh, baked, or dried, though this process varied depending on the Indigenous group who harvested them (Kuhnlein & Humphries, 2017). In this section we will explore how various groups approached this task.
The Manhousat began by creating two incisions: One to remove the mantle and soft internal organs (viscera), and one along the back of the chiton (Kuhnlein & Humphries, 2017). The second cut allowed them to bend the chiton around a surface to begin “ts’itskaa”, which means pounding. This was necessary in order to shatter the dorsal plates. Juvenile Manhousat often ate them raw after this point. Otherwise, chiton were brought to an “almost-boil” in a container filled with fresh water, after which the chiton were submerged in more (room temperature) fresh water and the remaining dorsal plates were removed. Finally, the chiton skin could be peeled, and then they could be eaten. A second method used by the Manhousat peoples was to soften Giant Pacific chiton by steaming them. Black Katy chiton were traditionally eaten with oil when prepared by the Manhousat peoples, though this was never done for Giant Pacific chiton. The Nootka peoples prepared chiton in a very similar way to the Manhousat peoples (Kuhnlein & Humphries, 2017).
The Kwakuitl were known to either simmer chiton or cook them in a fire before rinsing them, skinning them, and eating them (Kuhnlein & Humphries, 2017). The Tsimshian peoples were thought to have paired them with animal fats (Kuhnlein & Humphries, 2017).
Benefits & Nutrition
There is extremely limited information available about the nutritional benefits of Cryptochiton stelleri, specifically. A related species of chiton, “chiton articulatus” was found through atomic absorption spectrophotometry to have 320 mg/100g of sodium, 0.52 mg/100g of copper, 1.68 mg/100g of zinc, 18.01 mg/100g of iodine, 131 mg/100g of phosphorus, 2.66 mg/100g of iron, 17 mg/100g of potassium, 16.60 mg/100g of magnesium, and 125 mg/100g of calcium (Melo et al, 2011).
Limitations
Indigenous groups typically only harvested Giant Pacific chiton during low tides (Kuhnlein & Humphries, 2017). This, along with cultural traditions surrounding what time of year to catch chiton, creates some limits on when commercially sold Giant Pacific chiton could be harvested and sold to Indigenous communities. Overfishing of chiton is another possible issue. Not only could it threaten wild populations, it also goes against Indigenous views on overconsumption and respect for the natural world (Assembly of First Nations, n.d.).
References
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