Fossilised bioluminescent beetle discovered
Sometimes in nature, living things can glow...
From the microorganisms that create eerily glowing ocean tides, to various insects all over the world, biological light production is an everyday fact. The phenomenon is called ‘bioluminescence’, and happens through chemical reactions inside an organism’s body that produce light, in a very similar way to what you might see in a glow stick.
Bioluminescence has evolved independently more than thirty times. On land it is most common in beetles, where it is important for attracting mates, communication, and for luring food to a grisly death. However, little is known about how the ability to glow first evolved.
But this week, an international group of researchers have reported finding a crucial missing link: a fossilised beetle locked in amber. Dating from the prehistoric Cretaceous period, and dug up in an amber mine in Myanmar, it appears to represent a brand new bioluminescent species.
For contributing author Erik Tihelka, it was an exciting find. “Amber is the fossilised resin of ancient trees, and a lot of insects and other critters are fortunately caught up in this resin and fossilised so we have them preserved in three dimensions.
“Sometimes even the colours are preserved. It's a fantastic medium to work with; it's sort of like a real-life Jurassic Park.”
Crucially, the researchers spotted a part of the beetle that represents the remains of a light-producing organ called a ‘photic organ’ - similar to the light-producing organs of bioluminescent beetles today. Using this, as well as other traits, they’ve placed the creature onto a family tree.
The beetle appears to provide a missing step in the evolution of softer bodies in this family, and potentially links their bioluminescence to a big spread of flowering plants that happened during the Cretaceous period.
It could be that their glowing power evolved for defense against predators that are seen in fossils around the same time, such as early species of birds, ants, spiders, and frogs; and may have compensated for the beetles' softer-bodied larvae.
‘It's interesting, because while we have a rather solid understanding of biochemistry behind why some beetles produce light, it’s much more difficult to tell how all this originated,” said Tihelka.
The study, published in Proceedings of the Royal Society B, provides an interesting example of how fossils preserved in amber can shed crucial insight into how biological processes have evolved.