Red sea urchin
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| Strongylocentrotus franciscanus (Linnaeus, 1758) |
The Red Sea Urchin is a Sea Urchin found in the Pacific ocean, from Alaska to Baja California. It lives in shallow waters from the low-tide line to 90 m deep. It prefers to live in rocky ground that doesn’t get any extreme waves, and doesn’t have too much sand or mud.
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[edit] Physical Description
A Sea Urchin’s spherical body is completely covered by sharp spines that can grow up to 8 cm. These spines grow on a hard shell called the “test”, which encloses the animal. The oldest ones have been measured to be around 19 cm in diameter. It can vary in colour from red to dark burgundy. A sea urchin has no visible eyes or legs. It has a mouth located on its underside, which is surrounded by 5 teeth. During development, the Sea Urchin transforms itself from radial to bilateral symmetry, and then again from bilateral to radial. It crawls very slowly over the sea bottom using its spines as stilts, with the help of its tube feet. Scattered among its spines are rows of tiny tube feet with suckers that help it to move and stick to the sea floor.
[edit] Feeding Habits
The animals have a mouth with special jaws (Aristotle's Lantern) located on the bottom (oral) surface. Their preferred diet is seaweeds, kelp and algae, which they scrape off and tear up from the sea floor.
[edit] Behavior and reproduction
Sea Urchins are often found living in clumps. They have the ability to regenerate lost spines. Lifespan often exceeds 30 years, and scientists have found some specimens to be over 200 years old. Spawning peaks between June and September. Eggs are fertilized externally while they float in the ocean, and planktonic larvae (echinopluteus) remain in the water column for about a month before settling on the bottom of the sea floor, where they undergo metamorphosis into juvenile urchins. These juveniles use chemical cues to locate adults. Although juveniles are found almost exclusively under aggregated adults, the adults and juveniles are not directly related. Red Sea Urchins can effectively reproduce even if they are incredibly old.
[edit] Red Urchin Researchers
- Don Levitan (Florida State University, USA)
- Richard Strathmann (University of Washington, USA, )
- Tom Ebert (Oregon State, 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)
- Mike Nishizaki (University of Washington, USA)
- 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)
