Footage captured by a remote-operated deep sea research vessel offers a rare peek at a live shark embryo wriggling inside its egg casing. 

Researchers operating NOAA’s ROV Deep Discoverer spotted the embryo at a depth of 250 metres (820 feet) off the west of Puerto Rico’s Desecheo Island. It is believed to be the embryo of a catshark in the genus Scyliorhinus; they have been recorded in the area and are known to lay egg cases on organisms like coral and sponges.

The egg casings of oviparous sharks – sometimes also called mermaid's purses – contain many of the vital amenities that support life. The pinkish yolk sac seen at one end of the casing provides nutrients for the mini shark until it is ready to emerge. And as for that wriggling movement, that helps stimulate the flow of oxygen between the egg and surrounding water, allowing the babies to breathe as they grow (although this little predator-in-the-making may also have been wriggling in response to light from the ROV).

Catsharks belong to a family of small, bottom-dwelling sharks that spend their days cruising the coastal shallows. Perhaps the most well-known family member is the bashful "shyshark", which gets its name from a particularly adorable defence behaviour: when threatened, it wraps its tail over its eyes!

2014 12 04 Shark Embryo Related Content

Top header image: Ken-ichi Ueda/Flickr