Shark pups open eyes and change fins early

April 3, 2007

Miss Harahush and a bamboo shark pup. Credit: UQ

Baby sharks grow slowly, changing their fins as they grow and can see a month before they leave their eggs, according UQ research.

UQ Marine Science PhD student Blake Harahush, of the School of Biomedical Sciences, has been studying the growth and visual development of brown banded bamboo sharks from embryo to adult for the last three years.

After observing the growth of more than 13 pups, Ms Harahush found that sharks showed signs of fins at about 53 days into an average hatching period of 153 days, which varied depending on incubation temperature.

Warmer temperatures sped up growth with one bamboo shark hatched at 101 days.

Most other sharks take between a few months and two years to develop before birth.

She said they initially grew two long fins that she believed circulated fresh water and fresh oxygen and cleared any waste from the egg case.

These fins then morphed into the normal dorsal, pelvic, pectoral and caudal fins.

She also found that sharks eyes' developed fully within their dark egg cases a month before hatching.

"It's still a mystery why they develop their eyes so early before they hatch," Miss Harahush said.

"I can't say all their internal organs are mature, but externally, the developing sharks appear just like hatchlings at about 115 days.

"Sharks are not out to hunt humans. Bamboo sharks might suck on your toe but only if you put it in their mouth."

Her study of sharks, from Underwater World at Mooloolaba, is believed to be the second comprehensive scientific study of sharks from embryo to adult.

The 24-year-old American student from Maryland finished her UQ Honours degree in 2004 and is now in the third year of her PhD.

Her research will appear in the Journal of Fish Biology in coming months.

Source: University of Queensland