Alright, another strange Jellyfish question. This occurred in Viareggio, again in Italy, durring the early summer of last year. I was swimming in the sea, in which at first I did not see a single jellyfish, when all at once I was swimming in what was something like two parts jellyfish to one part water, if you get my drift. I know that now sudden blooms of medusae in the Mediterranean have been becoming common, but here's where it gets a little weird: every last one of them were dead, and their tentacles missing. What could have caused this? At first the only explaination I could think up was that perhaps they die after breeding, and that their tentacles had been chewed off. Which, nonetheless, makes little sense to me. And seeing that a creature whose body is 97% water decays quite rapidly as it is, I wouldn't think that their tentacles just happened to rot away first. I supposed it's worth noting that, although varying in size, all of the dead jellyfish were of the same species. All other types of jellyfish I saw that day in the area were alive and intact. Any ideas?

I was in Isola d'Elba, an island off the coast of Tuscany, early last spring durring an enormous jellyfish bloom. At about mid-afternoon, before which the waters had been essentially clear of jellyfish, the area became completely swarmed all in about a period of twenty minutes. It consisted almost entirely of one species, which were obviously a type of comb jelly but whose description does not match anything I have been able to find on the net. They looked like Mnemiopsis, but were pinkish-orange in color (and relatively opaque), about twenty centimeters in length, and were covered in conicle, spike-like protrusions.

Among these were also a few individuals of a couple other species I have not been able to find information on. These include a type that was the exact size, color, and shape of a chicken egg, and another which was flat and resembled an elongated, outstretched pair of wings with a span of about 160 cm.

All of the species I have listed above were bioluminescent, emerged at the same time, dissolved easily to the touch, and did not sting (these being traits of jellyfish that live in the abyss, which therefore should not have been in shallow water to begin with). Unfortunately, I did not have a camera at the time and thusly can only describe them as best I can, but any information you might have on them would surely put my curiosity at ease.

As a young child, I used to love putting the shells like the ones in the picture, into my ear to listen to them. I remember being told that you hear the waves in them. I know that's not entirely true, but what exactly causes the sound we hear? And why don't we hear such sounds if we put other objects like it up to our ear?

While swimming one morning across Coogee Bay in New South Wales, we came across thousands of these strange creatures (see photo) floating at depths down to about 2 metres.

They were hard but also flexible, with water inside and a small hole at one end. Their length varied from about 3 to 30 centimetres and their walls were between 2 and 5 millimetres thick. Their skin was marked with many small protrusions, the size of which varied from one creature to another. Unlike jellyfish they appeared to be completely harmless.

No one I've spoken to from the area has ever come across anything like this. So what were they and why were they there?

Philippe Wilmotte, Maroubra, New South Wales, Australia

I noticed this creature floating near the recreational pier at Rocky Point Park, in Port Moody, BC. It appeared to swim by curving/swinging its body side-to-side, as if it were a tail, and appeared to be similar in size to the fist of a child. There were a number of jellyfish in the waters at the same time, and at first, I assumed it was a type of jellyfish. Can anyone identify this creature?

Peter Buckley, Toronto, Canada

During the last 100 years, humans have been burning oil, natural gas, peat and coal. In the next 50 years we will burn even more. Burning hydrocarbons produces carbon dioxide and water. How much has this water added to sea-level rise?

Alfred Jacobsen, The Netherlands

Last week me & my family were down the beach in Suffolk, UK and as soons as we packed up a storm appeared. As we got soaked walking back we saw a fork of lightning strike the sea (North Sea).

My question is what happens when lighting strikes the sea? Or more to the point; how much of the sea is affected by the strike? Will it kill the fish? What would have happened if a human was in the sea? 

I am guessing that it would affect the wildlife but I am not sure if the large mass of water would disperse the energy and affect it less.