Crafty camouflage

Last week we brought you snails that attach all manner of pebbles, fossils, corals and shark teeth to their shells. Today we give you a newly-discovered fossil green lacewing larva that attached pieces of soil to its body as an act of camouflage. Our research fellow Ricardo Pérez-de la Fuente, lead author of the new paper, explains…

Visual camouflage is one of the most successful survival strategies in nature. Camouflaging is usually defensive, allowing animals to be left unnoticed by their predators, but it can also be used aggressively by predators themselves to approach their prey undetected.

Some camouflaging animals can actively change their colouring to match that of the background ‒ a technique called crypsis. Others can make their bodies resemble elements of the environment, such as leaves or twigs, which is called mimicry.

Italochrysa italica, an extant green lacewing larva carrying a dense debris packet made of soil fragments. Taken from the open access publication Tauber & Winterton, 2014.

Yet another approach to camouflage involves collecting diverse materials from the environment and incorporating them on the animals’ bodies in order to better blend with the surroundings. This is known as debris-carrying, trash-carrying, or decoration, and it can be found across a wide variety of animals including sea urchins, gastropods, and arthropods, such as decorating crabs, or sand- and mud-covering spiders.

My colleagues and I have just published the discovery of a fossil green lacewing larva, pictured at the top of the article, that has been preserved carrying bits of soil that it used for camouflage and physical protection. It’s a new larval species just 1.5 mm in length, and is preserved in Early Cretaceous Lebanese amber. We have named it Tyruschrysa melqart after the Phoenician city of Tyre and its tutelary god Milk-Qart (if you want to learn the reasons behind this name check out our open access paper!).

Interpretative drawing of Tyruschrysa melqart: body in grey, ‘tubes’ with setae coloured according to which body part they are attached to, and soil debris in brown.

Green lacewing larvae are active predators that eat other insects such as aphids, using sickle-shaped ‘jaws’ to pierce their prey, suck out their fluids and liquefy their tissues; eating is easier when there is no need to chew! Some green lacewing larvae are debris carriers, entangling all kinds of debris among their velcro-like ‘hairs’ called setae, which extend from relatively short ‘bumps’ on their backs. This debris is carefully selected and gathered with meticulous head and body movements to form a so-called debris packet on the back of the insect.

‘Tubes’ bearing setae of Tyruschrysa melqart, with detail of their mushroom-shaped endings (bottom), used for anchoring bits of soil.

The new fossil and similar ones described from younger Cretaceous ambers differ from modern relatives because instead of short ‘bumps’ with setae on their backs they have relatively long ‘tubes’, giving them a bizarre appearance.

These tubes have setae with mushroom-shaped endings of a kind never seen before in extinct or living green lacewing larva species. The mushroom-shaped ending is a special adaptation to anchor debris, which in the case of Tyruschrysa melqart are fragments of soil.

Hallucinochrysa diogenesi, another Cretaceous green lacewing larva bearing long ‘tubes’ with setae on its back, but carrying a debris packet made of plant hairs (trichomes). Preserved in Spanish amber (105 million years old).

It was already known that Cretaceous green lacewing larvae like Tyruschrysa had long tubes on their backs and that they collected plant hairs and other plant material to construct their packet of debris. But thanks to the new discovery we now know that these immature insects also used bits of soil, and that in the deep past debris packets were probably as diverse as those we see today.

Green lacewing larvae have been gathering debris to camouflage and protect themselves for about 130 million years, giving rise to the different body adaptations we see amongst these fascinating tiny collectors.

‘A soil-carrying lacewing larva in Early Cretaceous Lebanese amber’ Ricardo Pérez-de la Fuente, Enrique Peñalver, Dany Azar and Michael S. Engel is published as open access in Scientific Reports this month.

Imitation game

Last month we had the pleasure of hosting artist and scientist Dr Immy Smith as part of her week-long takeover of @IAmSciArt on Twitter. Drawing inspiration from the Museum’s collections, Immy has created some beautiful paintings. Here she tells us a little more about her interests and work…

My current artwork is focused on crypsis and mimicry – the ways that animals and plants disguise themselves or pretend to be something they’re not. Cryptic camouflage helps animals to avoid being seen, often to help them catch prey – or to avoid becoming prey themselves! Mimicry is also often about trying not to get eaten: the harmless hornet moth, for example, mimics a stinging insect to deter predators. I use these themes to develop print art projects, and also public workshops to help people learn more about the ecology of cryptic animals.

Cryptic Cards by Immy Smith

In my arts practice I try to imagine how animals and plants might evolve to camouflage themselves on human-made materials, and what they might look like. Will we one day find moths adapted to hide on advertising hoardings, or beetles mimicking litter? I made an entire deck of Cryptic Cards as a response to this kind of question.

Another project I’m working on at the moment is called Emergent Crypsis. This is a collaboration with Norweigan generative artist Anders Hoff who makes art using algorithms executed by a computer. I’m imagining how creatures might adapt to an extreme example of human-made patterns – computer generated abstract images.

Violin Beetle (Mormolyce phyllodes) by Immy Smith

My work requires me to closely study many animals and plants, but how do I learn about all these species in order to draw their imaginary relatives? How do I make my art a convincing representation of how life might find ways to hide on human-made art?

One answer is of course, the internet. I’ve been lucky enough to find many wildlife photographers online who are kind enough to let me use their images as reference. But photographs alone are not always enough to get to know the fine details and defining characteristics of a species: the joints and articulations of small insects, for example, are best studied from specimens. And some species are rare, or even extinct, and it can be hard to find photographic a reference.

Leaf-footed Bug (Diactor bilineatus) by Immy Smith

This is where scientific collections come into the picture. The collections held in museums and other institutions are not only essential for scientists and scientific illustrators, they are also an invaluable resource for artists of many disciplines, science communicators, and educators of many kinds. In the collections at the Oxford University Museum of Natural History I can photograph and sketch leaf-mimicking insects, for example, that are native to the forests of South America which I may never visit. I can study in minute detail the articulation of beetles that are rarely seen, and which might be difficult to find – and irresponsible to collect – myself.

A display of terrestrial bugs (Heteroptera) in the Museum, including the Leaf-footed Bug painted by Immy Smith

Not only do I find specific species that I want to study in natural history collections, I often see new ones – animals I didn’t know about or hadn’t thought of drawing before. In the same week that I visited Oxford, I also made a trip to Herbarium RNG in Reading to study plant mimicry, and found similar inspiration there. I can channel all this into both aesthetic art destined for print and sciart workshops that communicate the wonders of insects or plants with the wider community.

Working on sciart projects and educational workshops helps me appreciate the multitude of ways in which collections benefit research and education. We must try to communicate the plethora of roles they play, and the host of ways they cross into our lives – whether through scientific research on insects pollinators of the crops we eat, or via a deck of cards made by someone like me for mainly recreational purposes. We must fight to protect scientific collections because they are a resource that benefits all of us as a society.