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Conceived in the open sea, tiny spaceship-shaped sea urchin larvae search the vast ocean to find a home. After this incredible odyssey, they undergo one of the most remarkable transformations in nature.

Every summer, millions of people head to the coast to soak up the sun and play in the waves. But they aren’t alone. Just beyond the crashing surf, hundreds of millions of tiny sea urchin larvae are also floating around, preparing for one of the most dramatic transformations in the animal kingdom.

Scientists along the Pacific coast are investigating how these microscopic ocean drifters, which look like tiny spaceships, find their way back home to the shoreline, where they attach themselves, grow into spiny creatures and live out a slow-moving life that often exceeds 100 years.“These sorts of studies are absolutely crucial if we want to not only maintain healthy fisheries but indeed a healthy ocean,” says Jason Hodin, a research scientist at the University of Washington’s Friday Harbor Laboratories.

http://staff.washington.edu/hodin/
http://depts.washington.edu/fhl/

Sea urchins reproduce by sending clouds of eggs and sperm into the water. Millions of larvae are formed, but only a handful make it back to the shoreline to grow into adults.


--- What are sea urchins?

Sea urchins are spiny invertebrate animals. Adult sea urchins are globe-shaped and show five-point radial symmetry. They move using a system of tube feet. Sea urchins belong to the phylum Echinodermata along with their relatives the sea stars (starfish), sand dollars and sea slugs.

--- What do sea urchins eat?

Sea urchins eat algae and can reduce kelp forests to barrens if their numbers grow too high. A sea urchin’s mouth, referred to as Aristotle’s lantern, is on the underside and has five sharp teeth. The urchin uses the tube feet to move the food to its mouth.

--- How do sea urchins reproduce?

Male sea urchins release clouds of sperm and females release huge numbers of eggs directly into the ocean water. The gametes meet and the sperm fertilize the eggs. The fertilized eggs grow into free-swimming embryos which themselves develop into larvae called plutei. The plutei swim through the ocean as plankton until they drop to the seafloor and metamorphosize into the globe-shaped adult urchins.


---+ Read the entire article on KQED Science: https://ww2.kqed.org/science/2016/08/23/sea-urchins-pull-themselves-inside-out-to-be-reborn/

---+ For more information:

Marine Larvae Video Resource
http://marinedevelopmentresource.stanford.edu/

---+ About KQED

KQED, an NPR and PBS affiliate in San Francisco, CA, serves Northern California and beyond with a public-supported alternative to commercial TV, Radio and web media.

Funding for Deep Look is provided in part by PBS Digital Studios and the John S. and James L. Knight Foundation. Deep Look is a project of KQED Science, which is also supported by HopeLab, the S. D. Bechtel, Jr. Foundation, the Dirk and Charlene Kabcenell Foundation, the Vadasz Family Foundation, the Gordon and Betty Moore Foundation, the Smart Family Foundation and the members of KQED.