Koh Tao Diving Adventure

GOTHENBURG, Sweden -- May animals have eyes that are incredibly complex – others manage without. Researchers at the University of Gothenburg have shown that sea urchins see with their entire body despite having no eyes at all. The study has been published in the scientific journal Proceedings of the National Academy of Sciences (PNAS).

Most animals react to light and have developed a very sophisticated way of seeing complex images so that they can function in their surroundings. Good examples include insects' compound eyes and the human eye. Charles Darwin and other evolutionary biologists were bewildered by the eye's complexity and wondered how this kind of structure could have evolved through natural selection.

But some creatures, such as sea urchins, can react to light even though they do not have eyes. Previous studies of sea urchins have shown that they have a large number of genes linked to the development of the retina, which is the light-sensitive tissue in the human eye. This means that sea urchins have several genes that are coded for a widely occurring eye protein, opsin.

"It was this discovery that underpinned our research," says Sam Dupont from the University of Gothenburg's Department of Marine Ecology, one of the researchers behind the study and co-authors of the article. "We wanted to see where the opsin was located in sea urchins so that we could find the sensory light structures, or photoreceptors. We quite simply wanted to know where the sea urchin sees from."

The research group behind the study showed that the photoreceptors seem to be located on the tip and base of the tube feet that are found all over the sea urchin's body and are used to move.

"We argue that the entire adult sea urchin can act as a huge compound eye, and that the shadow that is cast by the animal's opaque skeleton over the light-sensitive cells can give it directional vision," says Dupont.

After completing their PADI open water course, newly 'hooked' scuba divers Betsy and Stacy began their PADI Advanced open water course.

It was a chance for them to get their buoyancy perfect and explore to 30m on the deep dive, where we came across this beautiful banded shrimp!

The guys have been fun diving everyday since! Today we just got back from scuba diving Koh Tao's South-west Pinnacle and the Shark Island dive site to the south of Koh Tao - two of our best sites. The weather is scorching at the moment, in the mid 30s and very little wind so perfect Koh Tao diving conditions.

SYDNEY, Australia -- Fish are not renowned for their smarts, but new evidence suggests that they may even be able to use simple tools.

In a paper published today in the journal Coral Reefs, researchers from Macquarie University and Central Queensland University report on a tusk fish smashing open shells on an anvil to access the meat inside.

Tool use has long been associated with the rise of humans and a sure sign of intelligence. For a long time it was thought to be unique to humans, but studies soon showed that primates also used tools for various tasks such as cracking open nuts. More recently it has been revealed that a variety of birds also manufacture and use tools (eg New Caladonian Crows), which suggests that tool use in animals may be more common that once thought.

"The pictures provide fantastic proof of these intelligent fish at work using tools to access prey that they would otherwise miss out on," said Dr Culum Brown of Macquarie University.

"It is apparent that this particular individual does this on a regular basis judging by the broken shells scattered around the anvil."

Tool use is inherently difficult underwater especially for animals that lack hands but these fish have found an ingenious solution. The tusk fish holds the shell in its mouth and twists its head violently to land alternating blows on the shell until it cracks open.

"We really need to spend more time filming underwater to find out just how common tool use is in marine fishes," says Dr Brown, "It really is the final frontier down there."

Today saw our Dive boat off bright and early in the morning to Mango bay to see the school of fusiliers and some seahorses. Then off to explore the Sattakut Wreck.

In the afternoon we set off to double dive Koh Tao's famous Chumphon Pinnacle. Visibility was good at close to 30 metres. Water temperature at 40 metres 29 C, so it’s still rash vest weather!

On the second dive we explored the north eastern tip of the dive site. Soft corals and tiny baby barracuda schooling around the base of a small granite pinnacle, at about 30m, circling up and around to above the thermocline, where the visibility greatly increased and we were greeted by a school of chevron barracuda, definitely the highlight of the dive.

Tomorrow we’re off in the afternoon trip at 12 to the South-west Pinnacles and Shark Island I’ll be sure to attend.