Dr Andrew Gillis explains how an elephant fish embryo lives off a large yellow yolk sack for 7 to 10 months before hatching out as a fish.
Dr Gillis:
“This is a picture of an elephant fish embryo. Elephant fish are cartilaginous fishes, and are distant cousins of sharks, skates and stingrays. The elephant fish lives in deep water off the coasts of Australia and New Zealand, but migrates annually into shallow coastal bays to lay their eggs. I study the embryonic development of elephant fish, by collecting their eggs by SCUBA diving at their egg-laying grounds. Normally, an elephant fish embryo will live in their egg and feed off of their yolk supply for 7 to 10 months before hatching out as a completely self-sufficient juvenile. However, these embryos may also be cultured outside of their egg cases, as seen here. This allows us to observe and photograph the development and growth of this unusual fish.”

The diameter of the petri dish in the elephant fish picture is 10cm.

More info:
http://www.pdn.cam.ac.uk/~jag93

Music by Peter Nickalls:
http://www.peternickalls.com

Many thanks:
Graduate School of Life Sciences