Red sea urchin, giant red urchin • Strongylocentrotus franciscanus • Heiltsuk/Haíɫzaqv - c̓k̓víc̓ • Nuxalk - mtm
{Strongylocentrotus = ball of spines}
Left: photo by Wiebe Nijland. Right: top and bottom of a red sea urchin. Photo by Cody Gold.
Identification
This "ball of spines" species is usually a distinguishable red colour, though it can also be pinkish, reddish-purple or purple-black. Its tube feet are dark red. Both its test and its spines are the largest off the Pacific Northwest urchins. The test can grow up to 15 cm (6") across, but is a flatter shape as it reaches about the same height as the purple sea urchin test (5 cm or 2"). Its sharp spines reach up to 7.5 cm (3") long.
Habitat & Range
Red urchins are found in the rocky intertidal and subtidal areas of open coastlines, to a depth of 90 m (300"). They are especially common in areas with kelp. Their range stretches along the west coast of North America from the Gulf of Alaska to Baja California, and they are also found along the coast of northern Japan.
This "ball of spines" species is usually a distinguishable red colour, though it can also be pinkish, reddish-purple or purple-black. Its tube feet are dark red. Both its test and its spines are the largest off the Pacific Northwest urchins. The test can grow up to 15 cm (6") across, but is a flatter shape as it reaches about the same height as the purple sea urchin test (5 cm or 2"). Its sharp spines reach up to 7.5 cm (3") long.
Habitat & Range
Red urchins are found in the rocky intertidal and subtidal areas of open coastlines, to a depth of 90 m (300"). They are especially common in areas with kelp. Their range stretches along the west coast of North America from the Gulf of Alaska to Baja California, and they are also found along the coast of northern Japan.
Similar Species Purple urchins can be found in the same habitats, and individuals of both species are often found interspersed amongst each other (as seen in the bottom two photos). Some red urchins can be more purple in colour which could cause some confusion when the species are found together, in which case the spine length must be used to differentiate. The spines of red urchins are much longer than those of purple urchins, and are nearly as long as the width of the test. |
Human Uses
There are commercial fisheries for red, purple, and green urchins. Their gonads are shipped to Japan, where they are a delicacy. Urchins are often used as indicator species to monitor pollution levels because they are sensitive to changes in water quality.
Intriguing Info
While most red sea urchins live to about 30 years, some individuals can live for over 200 years!
Juvenile red sea urchins will shelter under the spines of adult urchins.
Red urchins eat mostly bull kelp and giant perennial kelp, though they will also eat slow-moving invertebrates. Sea otters are a main predator of red sea urchins, but these urchins are also eaten by some crabs, snails, fish, and sea star species, including sunflower stars and leathers stars.
Red urchins play a similar ecological role as purple and green urchins, and face similar conservational issues. As they are a keystone species, there is a fine balance between too few and too many urchins. Too few affect precarious sea otter population levels, and too many result in urchin barrens. See the "Intriguing Info" on purple sea urchins for more information.
iNaturalist
https://www.inaturalist.org/taxa/49126-Strongylocentrotus-franciscanus
There are commercial fisheries for red, purple, and green urchins. Their gonads are shipped to Japan, where they are a delicacy. Urchins are often used as indicator species to monitor pollution levels because they are sensitive to changes in water quality.
Intriguing Info
While most red sea urchins live to about 30 years, some individuals can live for over 200 years!
Juvenile red sea urchins will shelter under the spines of adult urchins.
Red urchins eat mostly bull kelp and giant perennial kelp, though they will also eat slow-moving invertebrates. Sea otters are a main predator of red sea urchins, but these urchins are also eaten by some crabs, snails, fish, and sea star species, including sunflower stars and leathers stars.
Red urchins play a similar ecological role as purple and green urchins, and face similar conservational issues. As they are a keystone species, there is a fine balance between too few and too many urchins. Too few affect precarious sea otter population levels, and too many result in urchin barrens. See the "Intriguing Info" on purple sea urchins for more information.
iNaturalist
https://www.inaturalist.org/taxa/49126-Strongylocentrotus-franciscanus
References
(2005). Red sea urchin Strongylocentrotus franciscanus. BBC Science and Nature. British Broadcasting Corporation. Accessed 29/06/2013.
Cowles, D. (2005). Strongylocentrotus franciscanus (A. Aggasiz, 1863). Invertebrates of the Salish Sea. Rosario Beach Marine Laboratory. Accessed 29/06/2013.
Harbo, R. M. (1999). Whelks to whales: Coastal marine life of the Pacific Northwest. Madeira Park, BC: Harbour Publishing. P. 145.
Authors and editors of page
Kelly Fretwell and Brian Starzomski (2013).
(2005). Red sea urchin Strongylocentrotus franciscanus. BBC Science and Nature. British Broadcasting Corporation. Accessed 29/06/2013.
Cowles, D. (2005). Strongylocentrotus franciscanus (A. Aggasiz, 1863). Invertebrates of the Salish Sea. Rosario Beach Marine Laboratory. Accessed 29/06/2013.
Harbo, R. M. (1999). Whelks to whales: Coastal marine life of the Pacific Northwest. Madeira Park, BC: Harbour Publishing. P. 145.
Authors and editors of page
Kelly Fretwell and Brian Starzomski (2013).