An American research submarine has captured incredible footage of a shark embryo wriggling and feeding inside its eggcase.
Scientists aboard the Okeanos Explorer filmed the remarkable images near an island off the west coast of Puerto Rico, in the Caribbean, on November 15 as part of their work with the US National Oceanic and Atmospheric Administration.
The video, filmed by the Explorer’s remote submarine, initially shows what appears to be a bare coral substrate reaching out into the ocean like a long hair from the sea bed.
But as the camera zooms in, the eggcase comes into focus, showing a yolk sac and a baby shark moving back and forth in the tubular case attached to the coral.
“The shark moves backwards and forwards to bring in oxygenated seawater through small slits along the edge of the eggcases and it will also open and close its mouth to pump water over the gills,” said Cat Gordon, a conservation officer at the UK-based Shark Trust who estimated the embryo to be about four or five months old.
Cat Gordon said it was likely to be a catshark, the largest shark family with around 160 different species.
Most catsharks are small and eggcases can often take between five and nine months to hatch, she added.
“The embryo will continue to absorb the yolk sac as it develops, so similar to a bird’s egg, and then when fully developed it will push through the top of the eggcase and emerge as a perfectly formed miniature version of the adult.
“Sharks don’t have any parental care so it will have to fend for itself straight away,” she added.
The empty eggcases, nicknamed mermaids’ purses, can often be found on beaches around the UK.
“We’ve got a citizen science project called the Great Eggcase Hunt which encourages members of the public to get out on the beach and search for empty eggcases,” said Cat Gordon.
“We’ve had over 200,000 records submitted from all around the world now, but sadly never from the Caribbean.”