Sunday 21 January 2018

Still unclear why dolphins jump out of water

Jim Hurley - Nature trail

It is no small challenge to find out why dolphins jump.
It is no small challenge to find out why dolphins jump.

Why do dolphins jump out of the water? These marine mammals have been recorded jumping seven metres vertically, as high as a bungalow. So, why do they do it?

There has been a lot of debate over the years as to why dolphins regularly jump out of the sea. Some scientific studies have been carried out to try to shed light on the behaviour and while much has been written and stated, the bottom line is that nobody really knows why they do it.

That said, it hasn't stopped theorists from speculating. Several possible explanations have been suggested and it appears that the answer may be a combination of different reasons depending on the species and the circumstances involved.

If you try to walk quickly through waist-deep water, be it in the sea or in a swimming pool, it is a common experience that it is much more difficult to walk in water than in air. Dolphins may therefore take to the air to save energy and to increase their speed when travelling fast. By taking to the air they gain the duel advantage of 'swimming' in the less dense and less resistant medium and their need to breathe it.

Another suggestion is that they jump to see. In inshore waters they may use the shape of the coastline for navigating. They may also be looking for flocks of feeding seabirds thereby indicating where fish are congregated. Or they may be monitoring the positions of other members of their pod. How well they see in air and what exactly they see is, of course, unknown.

Another suggestion is that they jump to make splashes as a means of non-verbal communication over long distances when they go silent as they go into hunting mode closing in on prey. They may also jump when frightened to warn others of the presence of a potential predator such as a large shark or a Killer Whale.

Another suggestion is that since they have no means of scratching at sea they jump to rid their skins of irritating parasites. They do, of course, have the sandy seabed to scratch against.

And the final suggestion is that dolphins jump for the sheer hell of it! It may simply be fun, recreation, play, sheer joie de vivre.

Science is all about designing experiments and controls to test and re-test ideas like those outlined above. Though exciting, it is no small challenge to find out why dolphins jump.

Wexford People

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