This article, written by James B. Barnett, McMaster University, originally appeared on The Conversation and has been republished here with permission:
What would you do if you could be invisible? Would you use your power for good? For evil? Or just to avoid awkward conversations?
Transparency may seem like the simplest form of camouflage, but in the last year, research has revealed new complexities behind what some animals do to vanish into their surroundings.
In my research, I have experienced first-hand how effective and sophisticated transparency really can be. That story begins on a dark night in the pouring rain in the thick of French Guiana’s tropical rainforest.
My colleagues and I could only see as far as the beams of our headlamps would permit. We scanned the branches overhead for the source of a strange, high-pitched chirp: an almost metallic sound cutting sharply through the nightly cacophony of buzzing, rasping and squeaking.
Finally, our headlamps revealed a pair of googly eyes peering down on us, and we knew we had found what we had been searching for: a tiny glass frog (Teratohyla midas), only a couple of centimetres long. These bizarre frogs have transparent skin that lets us look directly at their intestines and bones — even at their beating hearts.
Transparent, not invisible
Glass frogs are an amazing sight but seeing one raises an interesting question: what’s the point of having transparent skin if your predators can still see you, or your internal organs?
Let’s take a step back to see how transparency works and understand why we’re not constantly bumping into invisible creatures. Although transparency seems like an obvious type of camouflage — if that’s not too much of a contradiction in terms — becoming transparent is not easy.
We can see what’s around us because of how different objects interact with light. If something is opaque, light is either reflected or absorbed at its surface. For something to be transparent, light must instead travel straight through it.
But as light moves between transparent materials it can be bent and scattered. Think about how a straw in a glass of water appears to bend. This is refraction, and results from the different ways that light moves through air and water.
An animal’s body is made up of many organs and tissues, each with a different thickness, structure and chemical makeup. For the animal to be transparent, light must not be reflected, absorbed, scattered or refracted as it travels through each of these different layers.
Water-dwelling animals are at a clear advantage in terms of achieving transparency. Animal bodies are mostly made of water, and if a creature is already in the water, there is much less refraction and scattering of light. As a result, some of the most effective examples of transparency are oceanic species like jellyfish and shrimp.
On land, transparency is much rarer, but we are now learning that it can be very effective, sometimes in unexpected ways.
Clearwing butterflies, for example, are not bound by the colours and patterns other butterflies use to blend into specific backgrounds. Instead, their fully transparent wings mean that predators look straight through them, and they can blend effectively into any background.
Several large moth species have taken a different route. Instead of making the whole wing transparent, their wings have transparent panes that allow patches of the background to show through. By combining these transparent panels with opaque colours, the wing surface is broken up and the moth transformed into an unrecognizable mosaic.
Translucence
So, what of our little transparent frogs back in the rainforest? Here, transparency provides yet another form of camouflage. Unlike butterflies and moths with their transparent wings, these frogs have all of their internal organs on show, preventing true transparency. Instead, by combining their transparent underside with a green topside, the frogs become translucent: allowing some light through but not showing a clear image.
Their green colouring is a close match to that of a generic leaf, and the trick of translucency allows the frog to brighten or darken in keeping with the leaves around it. What’s more, the frogs’ legs are more translucent than their bodies, providing an extra advantage from a process called “edge diffusion,” further blending frog and leaf together in the eyes of its predators.
Transparency makes animals hard to find, but there are many ways for animals to achieve invisibility.
Understanding how animals evade detection can help us protect species as humans continue to change the natural world around us.
NAIROBI, Kenya (AP) — The body of Ugandan Olympic athlete Rebecca Cheptegei — who died after being set on fire by her partner in Kenya — was received Friday by family and anti-femicide crusaders, ahead of her burial a day later.
Cheptegei’s family met with dozens of activists Friday who had marched to the Moi Teaching and Referral Hospital’s morgue in the western city of Eldoret while chanting anti-femicide slogans.
She is the fourth female athlete to have been killed by her partner in Kenya in yet another case of gender-based violence in recent years.
Viola Cheptoo, the founder of Tirop Angels – an organization that was formed in honor of athlete Agnes Tirop, who was stabbed to death in 2021, said stakeholders need to ensure this is the last death of an athlete due to gender-based violence.
“We are here to say that enough is enough, we are tired of burying our sisters due to GBV,” she said.
It was a somber mood at the morgue as athletes and family members viewed Cheptegei’s body which sustained 80% of burns after she was doused with gasoline by her partner Dickson Ndiema. Ndiema sustained 30% burns on his body and later succumbed.
Ndiema and Cheptegei were said to have quarreled over a piece of land that the athlete bought in Kenya, according to a report filed by the local chief.
Cheptegei competed in the women’s marathon at the Paris Olympics less than a month before the attack. She finished in 44th place.
Cheptegei’s father, Joseph, said that the body will make a brief stop at their home in the Endebess area before proceeding to Bukwo in eastern Uganda for a night vigil and burial on Saturday.
“We are in the final part of giving my daughter the last respect,” a visibly distraught Joseph said.
He told reporters last week that Ndiema was stalking and threatening Cheptegei and the family had informed police.
Four in 10 women or an estimated 41% of dating or married Kenyan women have experienced physical or sexual violence perpetrated by their current or most recent partner, according to the Kenya Demographic and Health Survey 2022.
TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.
Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.
Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.
The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.
The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.
It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.
Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.
Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.
Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.
Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.
Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.
The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”
VICTORIA – The British Columbia government is partnering with a bear welfare group to reduce the number of bears being euthanized in the province.
Nicholas Scapillati, executive director of Grizzly Bear Foundation, said Monday that it comes after months-long discussions with the province on how to protect bears, with the goal to give the animals a “better and second chance at life in the wild.”
Scapillati said what’s exciting about the project is that the government is open to working with outside experts and the public.
“So, they’ll be working through Indigenous knowledge and scientific understanding, bringing in the latest techniques and training expertise from leading experts,” he said in an interview.
B.C. government data show conservation officers destroyed 603 black bears and 23 grizzly bears in 2023, while 154 black bears were killed by officers in the first six months of this year.
Scapillati said the group will publish a report with recommendations by next spring, while an independent oversight committee will be set up to review all bear encounters with conservation officers to provide advice to the government.
Environment Minister George Heyman said in a statement that they are looking for new ways to ensure conservation officers “have the trust of the communities they serve,” and the panel will make recommendations to enhance officer training and improve policies.
Lesley Fox, with the wildlife protection group The Fur-Bearers, said they’ve been calling for such a committee for decades.
“This move demonstrates the government is listening,” said Fox. “I suspect, because of the impending election, their listening skills are potentially a little sharper than they normally are.”
Fox said the partnership came from “a place of long frustration” as provincial conservation officers kill more than 500 black bears every year on average, and the public is “no longer tolerating this kind of approach.”
“I think that the conservation officer service and the B.C. government are aware they need to change, and certainly the public has been asking for it,” said Fox.
Fox said there’s a lot of optimism about the new partnership, but, as with any government, there will likely be a lot of red tape to get through.
“I think speed is going to be important, whether or not the committee has the ability to make change and make change relatively quickly without having to study an issue to death, ” said Fox.
This report by The Canadian Press was first published Sept. 9, 2024.
