Red Sea Urchin
| Red Sea Urchin | ||||||||||||||||||
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| Binomial name | ||||||||||||||||||
| Strongylocentrotus franciscanus (A. Agassiz, 1863) |
The Red Sea Urchin (Strongylocentrotus franciscanus (A. Agassiz, 1863), is a species of marine invertebrate belonging to the phylum Echinodermata or "spiny-skinned" animals. Typically found in the Pacific ocean from Alaska to Baja California, red urchins inhabit shallow waters from the low-tide line to 90 m deep. In general, this species prefers wave-sheltered rocky shorelines.
Physical Description
During larval development, the body of a sea urchin transitions from radial to bilateral symmetry. This bilaterally symmetrical larva, called an echinopluteus, subsequently develops a type of pentaradiate symmetry that characterises echinoderms. As adults, the body, or test, can reach up to 24 cm and can vary in colour from red to dark burgundy. The test is covered by sharp spines that can grow up to 8 cm. Among the spines are rows of tiny tube feet each terminating with a suction cup. In addition, the body is also covered with small pincer-like structures called pedicellaria.
The mouth of an urchin, called the Aristotle's lantern, consists of 5 teeth and is located on the underside (or oral) of the body. Waste is excreted from an opening on the upper side (or aboral) of the body. During reproduction, eggs and sperm are also released from the aboral side of the body through 5 small openings called gonopores.
Feeding Habits
Red urchins will eat a wide range of foods, both plant and animal. However, brown kelp is the preferred food item and in the Pacific Northwest, it is specifically bull kelp (Nereocystis leutkeana)[1]. During larval development, urchins use bands of cilia to capture food from the water column [2] .
Behavior and reproduction
Lifespan in red urchins often exceeds 30 years, and recent evidence indicates that some individuals are over 100 years old.[3]. Urchins are known as broadcast spawners, where gametes are released into the water and fertilization occurs in the water column. Spawning peaks between June and September and planktonic larvae (echinopluteus) remain in the water column for about a month before settling on the bottom of the sea floor. Once settled, larvae undergo metamorphosis into juvenile urchins. These juveniles are found almost exclusively underneath adults [4] [5] . and may utilize chemical cues to locate adults. Although juveniles are found almost exclusively under aggregated adults, the adults and juveniles are not directly related.
References
- ↑ Vadas R.L. 1977. Preferential feeding: An optimization strategy in sea urchins. Ecological Monographs 47: 337-371.
- ↑ Strathmann, R 1971. The feeding behavior of planktotrophic echinoderm larvae: mechanisms, regulation, and rates of suspension feeding. Journal of Experimental Marine Biology and Ecology 6: 109–160.
- ↑ Ebert, TA and JR Southon 2003. Red sea urchins can live over 100 years: confirmation with A-bomb [14.sup]carbon - Strongylocentrotus franciscanus. Fishery Bulletin, 101(4): 915-922.
- ↑ Low, CG 1975. The effect of grouping of Strongylocentrotus franciscanus, the giant red sea urchin, on its population biology. Ph.D. thesis, University of British Columbia, Vancouver, BC.
- ↑ Tegner MJ and PK Dayton 1977. Sea urchin recruitment patterns and implications of commercial fishing. Science 196: 324-32.
Red Urchin Researchers
- Don Levitan (Florida State University, USA)
- Richard Strathmann (University of Washington, USA, )
- Tom Ebert (Oregon State, USA)
- Louis Botsford (UC Davis, USA)
- Paul Dayton (SCRIPPS, USA)
- Laura Rogers-Bennett (UC Davis, USA)
- Jane Watson (Malaspina University-College, Canada)
- Rick Harbo (DFO, Canada)
- Alan Campbell (DFO, Canada)
- Lance Morgan (MCBI, USA)
- Mike Hart (Simon Fraser University, Canada)
- Louis Botsford (UC Davis, USA)
- Richard Emlet (University of Oregon, USA)
- Mike Russell (Villanova, USA)