Weird Gramma
Previous Editions
A horn shark’s spiral egg case, found at Corona del Mar, California.
Photo: D.J. Eernisse_c_2002
WeirdFins
THE SHARK’S PURSE
Horn shark, Heterodontus francisci, from southern California.
NOAA/Southwest Fisheries Science Center

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Howdy, Weird Gramma here with “WeirdFins,” all about strange stuff in the sea, and brought to you by the National Oceanic and Atmospheric Administration. Now, Kristin, in La Cañada, California, asks if it’s true that some sharks carry purses. Well, yes, but maybe not like you’re thinking. The sharks are “horn sharks” and the “purses” are really their egg cases being carried in the mother’s mouth. Egg cases are laid by some kinds of sharks, and most skates and stingrays. After the pups hatch out, egg cases sometimes wash up on the shore and beachcombers call them “mermaids’ purses.”

Most egg cases have points or long, curlicue strings that attach to seaweed. But horn shark egg cases are big corkscrews, and unlike other sharks, the mother horn shark does a little parental care. She carries each egg case in her mouth while it’s still soft, looking for rocks to protect it until the pup hatches 8 or 9 months later. When she finds a good spot, she sort of screws the egg case into the rocky crevice, and when it hardens, most predators can’t get to it.

Horn sharks get their name from the thick, white spines at the front of the dorsal, or top, fins. Even the newborn pups have sharp little spines that help them from becoming lunch for larger fish. All of the 11 kinds of horn sharks are smaller than you are, and most of their teeth are blunt to help them crunch sea urchins, crabs, and other bottom-dwelling critters. They’re not often sold at markets or restaurants, but you can see horn sharks in many large aquariums and sea parks.

You can see pictures of horn sharks on the National Marine Fisheries Service WeirdFins link at www.nmfs.noaa.gov.

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