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Strongylocentrotus franciscanus - Red sea urchin
Geographic range:
Alaska to Cedros Island, Baja California
Key features:
Adults are either a deep red, almost black or a bright brick red. The spines are very long, and red urchins are usually much larger than nearby purple urchins.
Similar species:
Strongylocentrotus purpuratus -- Purple sea urchin
Habitat(s):
bay (rocky shore), exposed rocky shore, kelp forest, protected rocky shore
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Primary common name:
Red sea urchin |
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ITIS code:
157971 |
Synonymous name(s):
-- |
General grouping:
Sea stars, urchins, cucumbers, sand dollars, brittle stars |
| Geographic Range |
Range description:
Alaska to Cedros Island, Baja California. Reports from Japan are likely a misidentification of a sibling species. |
Northern latitude extent:
58.412079 |
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Southern latitude extent:
27.989393 |
East longitude extent:
-- |
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West longitude extent:
-- |
| Intertidal Height |
Lowest intertidal height:
meters OR -2 feet |
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Highest intertidal height:
meters OR 0 feet |
Intertidal height notes:
Usually found in tide pools and other low zones in the intertidal. |
| Subtidal Depth Range |
Minimum depth:
0 meters OR 0 feet |
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Maximum depth:
100 meters OR feet |
Subtidal depth notes:
Depending on the reference, the maximum depth is 90 or 125 m deep. |
| Habitats |
Habitat(s):
bay (rocky shore), exposed rocky shore, kelp forest, protected rocky shore |
Habitat notes:
Associated with rocky reefs, and usually kelp forests. |
| Abundance |
Relative abundance:
Uncommon. |
| Species Description |
General description:
Red urchins are the larger of the two species commonly occurring along the central coast of California, although they tend to be less abundant than purple urchins. Coloration of the spines and test can range from dark burgundy to brick red, and may include hints of dark purple. |
Distinctive features:
Deep or bright red color, large test diameter, and elongate spines characterizes the red urchin, separating it from the smaller purple urchin. |
Size:
Test diameter up to 11 cm. |
| Natural History |
General natural history:
Red urchins may live upwards of 20 years. Where their range overlaps with that of the sea otter, red urchins remain in rocky crevices to avoid being consumed. While in these crevices, the red urchins extend their tube feet, waiting for drift kelp to come within their grasp. In areas lacking predators, red urchins may move several meters per day in search of algae to graze.
Dispersal occurs during a planktonic phase, during which larvae remain in the water column for 2-4 months, carried by oceanic currents. Larvae settle in shallow habitats, usually cued by exudates from algae in the area. |
Predator(s):
Common predators, besides man, include southern sea otters Enhydra lutris nereis, sheephead wrasse Semicossyphus pulcher, and California spiny lobster Panulirus interruptus. |
Prey:
Red urchins feed on a variety of algal species, but prefer the giant kelp Macrocystis pyrifera. |
| Feeding behavior |
Feeding behavior(s):
Herbivore |
Feeding behavior notes:
Red urchins feed using a five-toothed structure called Aristotle's Lantern. The oral hole has soft tissue and through this the five bladed teeth are extruded, cutting the alga into smaller pieces that are ingested. In some cases, small invertebrates growing on the ingested alga are also consumed. |
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| February - July |
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Reproduction:
Gonads of males and females ripen in early spring, usually April and May in central California. Gametes are shed externally and fertilization takes place in the water column. Larvae then develop over a period of 2-4 months, riding oceanic currents the entire time. |
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Cordell Bank National Marine Sanctuary:
-- |
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Gulf of Farallones National Marine Sanctuary:
-- |
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Monterey Bay National Marine Sanctuary:
Although red urchins were commercially harvested beginning in the 1970s, the fishery peaked in the early 1990s, crashing precipitously until 1999. Currently it is still harvested. |
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Listing Status:
-- |
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Monitoring Trends:
-- |
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References:
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Carlton, J.T. 2007.
The Light and Smith Manual, 4th edition
Intertidal Invertebrates from Central California to Oregon
University of California Press. 1001 p.
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| Lamb, A. and B. P. Hanby. 2005. Marine life of the Pacific Northwest. Harbour Publishing. 398 p. |
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| Leet, W.S., C.M. Dewees, R. Klingbeil and E.J. Larson. 2001. California's living marine resources: a status report. California Department of Fish and Game. |
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| Morris, R.H., D.P Abbott, and E.C. Haderlie. 1980. Intertidal Invertebrates of California. Stanford University Press, Stanford, California. 690 p. |
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Data supplied by SIMoN Sanctuary Integrated Monitoring Network
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