What is a lava cricket? Lava crickets are a species of cricket that appear on freshly cooled lava and don’t seem to live anywhere else. Not a lot is known about them.
The Latin name for the lava cricket is Caconemobius fori. They are also called lava crickets, dark lava cricket, or ‘ūhini nēnē pele in Hawaiian. They are similar to other crickets in the way that they can jump, but they are vastly different in other ways. One of the ways that they are most different is that they only live on freshly cooled lava. Often, when a volcano erupts, lava springs forth. This lava can explode into the air, it can run down the sides of the volcano, or it can come out of the ground. The temperature of lava varies, but it is generally about 1,000 ℃. As long as it stays hot, it will remain a liquid and continue to flow downhill. However, once it is out of the volcano, it will begin to lose heat, beginning with its surface. As the molten lava loses heat to the air, it hardens and becomes rock. At first, the rock is too hard, too hot, and too barren for plants to grow. Plants need food and something to grow in, so it takes a while for the rocks to weather and debris to build up enough for plants to grow there. The lava also needs to cool down enough for plants to grow on it and that can take years if the lava is thick. It can take months for plants to appear or it can take decades. You would think that if plants can’t grow there, nothing can grow there, but that is not true. As soon as the lava cools and hardens, lava crickets appear.
Nobody knows where the lava crickets come from. Nobody knows where they live when they are not on the lava. They appear just after the lava has cooled and they disappear when the first plants start to grow there. They like to be there all on their own and they don’t like having any competition. As soon as there is competition, the lava crickets vanish and go … nobody knows where. They are pioneers because they colonize a habitat before anyone else, but this is what puzzles the scientists the most. Any species that is a colonizer has to be a generalist, because they don’t know what kind of environment they will be living in and they will have to cope with eating a whole range of things. They also can usually fly and reproduce very quickly. Lava crickets aren’t generalists. They are specialists in that they only really eat two things. Lava crickets eat dead plant matter that blows onto the lava, although, they won’t leave the lava to find dead plant matter that would be near the lava. This is odd because there must be far more dead plant matter near the lava than there is on it. And they eat, or drink, sea foam which blows in from the ocean. From this they get water and they get a protein called albumen, which is also found in eggs. And that is all they eat and drink. They can’t fly, and they reproduce very slowly. When they mate, the female lava cricket sucks about 8% of the moisture out of the male, which is quite hazardous in a hot environment. Because of this, the males are not very eager to mate.
A possible reason why lava crickets have evolved to live on cooled lava is to avoid competition and to avoid predators. There isn’t much to eat on the lava, so no other organisms try to live there, giving the lava crickets a monopoly on the food. The lava is still fairly hot, so no other animals live there and eat the crickets. It might also be difficult to see them because of the heat. None of these things apply to the time they spend when they are not on the lava, which is why nobody knows where they go or what they do. How do they know when there is new lava? How do they find it? Lava crickets don’t have any wings, so they cannot travel very far. How do they get to the lava when they do find it? They also can’t sing or chirp like other crickets, so, how do they signal to each other if they do find a lava field. So many things are still unknown.
Scientists wanted to test the lava crickets in a lab, but they weren’t sure how to catch them. It turned out that lava crickets love old cheese. Scientists put old cheese in traps made of wine bottles. Before long, they had managed to catch plenty of lava crickets to study. Maybe they will learn more about them soon. And this is what I learned today.
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Sources
https://en.wikipedia.org/wiki/Caconemobius_fori
https://www.atlasobscura.com/articles/extreme-life-lava-cricket
https://www.science.org/content/article/these-intrepid-crickets-hawaii-s-lava-home-sweet-home
https://www.sciencing.com/three-rocks-form-lava-cools-8097303
https://www.britannica.com/science/lava-volcanic-ejecta
http://scienceline.ucsb.edu/getkey.php?key=6109
Photo by Brent Keane: https://www.pexels.com/photo/lava-flowing-1687530/