NEWSROOM
Seahorse vertical swimming mystery solved
25 May 2009
Seahorses are among the most readily identifiable inhabitants of the marine world because of their habit of swimming upright. Yet even though seahorses can be found in many areas of the world, up until now, there has been no scientifically proven explanation as to how and why these shy creatures came to adopt their vertical posture.
Now researchers from Macquarie University have solved this marine mystery. Their explanation was published this month in the journal Biology Letters.Dr Peter Teske and Associate Professor Luciano Beheregaray found that seahorses evolved their upright position largely because of an expansion of seagrass habitats which occurred in Australasia around 20 to 25 million years ago during the Oligocene period. At that time, vast areas of shallow water allowed for the growth and expansion of seagrass – the habitat favoured by the seahorse.
Because there was no known link between seahorses and horizontally-swimming fish, and only two known fossil sites contain seahorses, scientists had difficulty in coming up with a satisfactory explanation for when seahorses evolved to swimming upright, Dr Teske said.
The answer came when they looked at the DNA of other fish belonging to the same family as the seahorse. The closest relative turned out to be the pygmy pipehorse – similar in looks to a seahorse – but a horizontal swimmer that prefers to live on reefs.
The scientists compared DNA and using molecular dating, were able to work out when seahorses and pygmy pipehorses diverged. They found that their last common ancestor lived around 25 to 28 million years ago – but with the emergence of the seagrass, conditions were favourable for the evolutionary split.
“The only major difference between seahorses and their pygmy pipehorse ancestors therefore is really just the upright posture. And that’s a small evolutionary step that probably did not require many genetic changes,” Teske said.
Any enquiries from the media should be directed to:
Lyn Danninger
phone:(02) 9850 7257
email address: lyn.danninger@pru.mq.edu.au
Featured News
- 9 February 2010 Expedition breaks new records in fight against rising oceans
- 5 February 2010 Researchers call for new approach to disaster preparedness and recovery
- 1 February 2010 Yaegl research collaboration hits new heights
- 27 January 2010 MGSM named among top 100 global business schools for MBA
- 27 January 2010 $25 million in new research funding
