Planet Earth

Catsharks in Waiting

These transparent eggs are where it all begins for small-spotted catsharks.

By Ernie MastroianniOct 2, 2014 5:00 AM
Ana Filipa Scarpa


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These transparent eggs, known colloquially as mermaids’ purses, hold embryonic small-spotted catsharks, or Scyliorhinus canicula.

The eggs, about 2 to 3 inches long, rest in a tank at the Aquário Vasco da Gama near Lisbon, Portugal. When the fish hatch, they’ll be 3 inches long, and they will eventually grow up to about 3 feet. According to the Florida Museum of Natural History, scientists use this common species as a marine version of a lab rat to research hormones, blood and organs.

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