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Urchin City

Writer's picture: Debra Quick-JonesDebra Quick-Jones

11/11/19

So much happening! I recently was lucky enough to go on a trip with the Nature Conservancy to Santa Cruz Island, off of Ventura, California. It was part of their outreach to show what the Conservancy is doing in the area of ocean conservation. A small group of us travelled to the island, doing some diving in the waters along the way. We saw both very healthy stands of giant kelp (the ones that create forests under the water) and urchin barrens, where urchins have lost their primary predators (sunflower sea stars, otters) and are eating themselves out of house and home. They tend to eat and sever the stipe or main stem of the algae plant, causing the whole 30 foot long plant to float away, unable to reattach itself to the rocks.

The Conservancy is monitoring areas of concern, especially in Northern California waters, and promoting a ranching style of aquaculture where good- sized individuals can be removed from these areas and raised in an aquaculture facility until they are fat and happy and producing lots of roe (eggs). The Roe is what makes sea urchins commercially desirable , but many of the wild ones are so underfed that they are not producing good quality roe. We could be their top predator and keep them from overgrowing their ecosystems.


The other most exciting thing is that my red rock crab, Cancer productus, has berried (produced brooding eggs) and released it’s zoea!(eggs hatched into larvae) When I acquired it on 10/4 it was showing no signs of eggs. It must have just mated just before during a soft shell period . Eggs were noticed on 10/19 and zoea noticed in aquarium 11/10, or approximately 3 weeks of brooding. Zoea look like tiny snowflakes, less than the size of a pinhead, propelling themselves around with their maxillipeds. They will stay this way suspended in the water as planktonic creatures through 4 molts before they metamorphose into something that at least looks somewhat like a crab, called a Megalopa. One more metamorphosis and they finally look like little adults.



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