We're delighted to present an extract from Wild and Wonderful, the new book by biologist, environmentalist and broadcaster Eanna Ni Lamhna, in bookshops now.

Glow-in-the-dark owls, eggs boiling in Icelandic hot pools, the gangster tactics of the devil's coach-horse beetle … Éanna Ní Lamhna has seen them all!

Éanna explores the wonders of our wild world, from a safari in Tanzania to the cloud forests of Costa Rica, from rat-hunting in Canada to whale watching in New Zealand. She draws on her experience as a diver to tell of face-to-face encounters with fascinating fan worms, elusive sea hares and a murderous crab, and rings the alarm bells on the environmental challenges facing us.

Éanna also recounts with cheerful relish the pitfalls and delights of being a broadcaster and a scientist. Sure why would anyone want to be anything else?

The nearest I will ever get to flying …

I always thought that night divers were mad. It’s scary enough going down during the day when you at least can see and know which way is down and which up. But at night the whole ball game changes. Just as different things come out in the garden at night when the great enemy of invertebrate life, the birds, have gone to bed, so too a whole different collection of animals emerges underwater when it becomes dark. Night diving to see these is something else. When I say dark, it really is dark down there. There is no ambient light from streetlights, no reflection from the sky – such weak light cannot penetrate down into the water. You are totally dependent on what you can see through the light of the torch. All around is a wall of darkness. Doesn’t do to think too much what might be out there lurking just beyond the reach of the torch.

At night the space seems much more enclosed. You are dependent on the quality of your diving gear and on the length of time the torch batteries will last underwater. But the lure of the completely different selection of wildlife (and the fact that my buddy promised to hold my hand the whole time) was stronger than my perfectly reasonable fears, and so it was that I found myself one dark night at the back of the car changing into my wetsuit and checking and double-checking the gear – contents gauge, life jacket, torch and batteries, reserve valves, regulator, knife, gloves (would I wear them or not?), compass – my only hope of knowing where I was going … In the end, I could delay no longer and off we went to the end of the pier to jump in.

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Listen: Wild And Wonderful - Eanna Ni Lamhna talks to Derek Mooney

And, first surprise, as we gazed down into the inky waters off that pier in County Wexford, it wasn’t all dark down there. Once anything hit the water a shower of sparks seemed to appear. There seemed to be tiny points of light in the water that only appeared when the water was disturbed and they were moved suddenly. These lights are, in fact, a phosphorescent kind of the plankton called dinoflagellates, which glow with a cold light when suddenly disturbed. By dropping in stones from the pier we could cause a shower of sparks to occur where the stones hit the water. The species in our waters is called Noctiluca – a nightlight, in other words. They are much more common in warmer waters where the wake of a passing ship can make a twinkling path in the water. Amazingly in this day and age, not a great deal is known about how this light is actually produced. The wonderfully named substance luciferin is involved. This does not, sadly, mean direct interference from the lower regions of the next world. The fact that Lucifer was the name of one of the four archangels who occupied the highest levels of heaven, above the cherubim and the seraphim, and who subsequently was expelled for the sin of pride, means that the name is forever associated with hell. But Latin scholars will know, of course, that the name merely means 'light carrier’ and this is what the luciferin in the Noctiluca does. When an enzyme in the cells of an organism that contains luciferin is oxidised, light is produced. Why it does so is another matter. Why would a big shoal of these tiny creatures draw attention to themselves in this way when disturbed? Surely they would provide a tasty mouthful for filter feeders higher up on the food chain, who would be attracted to their presence by the lights? But the study of evolution tells us that there must be something in it for the species itself or it would have caused its extinction long ago.

We couldn’t ponder evolution any longer. Was I getting in or not? And so we carefully descended the steps and got in very gently – no flamboyant leaping backwards off the edge here. The cold of the water as it filled the wetsuit was somehow reassuring in its unwelcome familiarity. And then down we went. The dive involved swimming along the bottom just above the rocks out off the coast to a depth of ten metres or so, and watching the night-time scene. And there was plenty to see.

There seemed to be an endless amount of crabs scurrying over the bottom, much more so than during the day. We were on the lookout for more exotic creatures: lobsters. They live in rocky crevices and defend the entrances to them with their large claws. During daytime if you were to spot a claw waving from a hole in the rock, any investigation would cause it to be drawn in sharpish. The holes are always bigger than the lobsters and they retreat at the slightest interference. But they are hunters, not filter feeders, so they must come out to find food and this they do under the cover of darkness. It is truly an astonishing sight to see a large dark-purple lobster walking backwards along the seabed. They can only go backwards, but they can certainly move with strong contractions of their tails when disturbed.

They are out searching for food and, like the crabs, they are scavengers. They will eat dead food and so play their role in tidying up the seabed by mopping up any dead or dying creatures they come across. Fishermen use this knowledge when they bait and sink lobster pots to catch them. The bait lumps of mackerel or other fish can be smelled from a distance and the lobster soon arrives. It reverses in through the opening in the pot and soon demolishes the tasty bait. But alas, it can’t turn around in the pot to reverse out the way it came, and it can’t move forward, so there it must remain until the pot is lifted. It is not injured or hurt in any way, just trapped. Crabs come into the pot as well, for they too are partial to pieces of dead fish and, by the time the fisherman comes to lift it, the crabs may be so numerous that they are fighting among themselves.

Wild and Wonderful is published by The O'Brien Press