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Local Intelligence | Sand Dollars
By HANK PELLISSIER
Published: January 8, 2011
Sand dollars are easily collected at Ocean Beach — a far safer hobby than swimming in the treacherous waves. The sand dollar is actually the endoskeleton of a populous sea animal, with 250 species worldwide. The local variety, Dendraster excentricus, is perhaps the strangest.
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Adithya Sambamurthy/The Bay Citizen
A sand dollar on Ocean Beach.
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The best time for beachcombers to look for sand dollars is at low tide right after a storm.
Spinal Species
Dendraster excentricus ranges from Alaska to Baja California, about 300 feet offshore from the low tide line, in up to 300 feet of water. Related to sea urchins, a live sand dollar has a velvetlike coat that is actually thousands of tiny spines, only one to five millimeters long.
Local Ingenuity
All sand-dollar species lie flat on the ocean floor, except Dendraster excentricus. The local sand dollars display an odd adaptation — they “stand up” to enhance their feeding ability. Burrowing their front ends into the sand, they hoist themselves upright into precise rows that parallel the current to snag plankton.
Float-Away Dollars
Storms are the enemies of sand dollars. After rough waves and strong currents dislodge them from the ocean floor, they drift helplessly, smashing against rocks, washing on shores and dying. The best time for beachcombers to find sand dollars is at low tide after a storm.
See Me, Feel Me
The Academy of Sciences in Golden Gate Park owns thousands of sand dollars, both fossils and living species. Thirty to 40 varieties are exhibited in Steinhart Aquarium.
Desperate Survivors
If a live sand dollar is washed ashore, it can crawl slowly back into the waves, or it can cover itself by burrowing into the sand. Seagulls can crack them open and eat them by carrying them aloft and dropping them onto rocks.
Unpalatable
Sea-urchin gonads, or uni, are a delicacy in sushi. Although sand dollars are closely related, they are not harvested as a food product, partly because their gonads are considerably smaller. Dr. Rich Mooi of the Academy of Sciences said the taste of sand dollars was “not very good.”
Pioneer Nickname
Experts believe East Coast settlers in the United States invented the term “sand dollar.” It was named for a smaller sand-dollar species found on the Atlantic coast that resembles the silver-dollar coins of that era.
Flaming Fun
Bonfires are allowed on Ocean Beach between Lincoln Way and Fulton Street, but alcohol and amplified sound are forbidden. An offshoot group from Burning Man is making metal fire rings for use by beach party-goers.
hpellissier@baycitizen.org
A version of this article appeared in print on January 9, 2011, on page A23B of the National edition.