Mammals that glow in the dark
1 WHAT ON EARTH IS GOING ON?
This is biofluorescence, where fluorescent proteins in living things reflect light. The light is absorbed at one wavelength (blue), then re-emitted at another (blue-green, green, pink, yellow or red). Over the past 50 years, the phenomenon has been seen in fungi and more and more groups of animals, including amphibians, fish, birds, scorpions and marine invertebrates. It occurs in shells, bones, muscle teeth, and keratin-based skin, beaks and feathers.
2 BUT WHICH MAMMALS CAN DO IT?
In the 1980s, biofluorescence was first documented in mammals when UV light was shone on museum specimens of North and South American opossums (their belly fur glowed candy-pink). All the species were nocturnal, which suggests the ability may have something to do with communication or camouflage in low light. Then, in 2019, came the discovery that North America’s three species of flying squirrel
( – also nocturnal – glow pink.
3 WILL WE FIND ANY MORE GLOWING MAMMALS?
We just have. In October 2020, US researchers announced that the platypus ( glows blue-green under UV light. As before, the chance discovery came while examining preserved ‘skins’. Hot on the heels of this, curators in Western Australia checked their own collection, and found that wombats also glow under UV. It shows the value of museum collections, and we may yet find more biofluorescent mammals.
Sperm
whales are the planet’s largest ‘active’ hunters – blue and fin whales may be mightier, but as filter feeders, don’t target individual prey items. However, size alone doesn’t make sperm whales immune to becoming prey themselves. Their main foes are killer whales, while other potential assailants include false killer whales and large sharks. Calves are most likely to fall victim and the adults will form a protective ring, known as marguerite formation, around any vulnerable group members.
Do sperm whales have predators?
Another, somewhat unexpected, adversary has recently come to light. Giant petrels and sperm whales both feed around longline fishing boats in the Southern Hemisphere, and the petrels have now been seen ripping chunks of flesh out of the whales. The birds bother the whales enough for them to give up and dive or take avoidance measures such as rolling. Laurie Jackson
SLIME MOULD
If we zoom in, a woodland floor becomes as otherworldly as the deep sea. Here, some slime mould of the species Stemonitis
provides a perch for an assassin bug, perhaps hunting springtails or other tiny creatures feeding on the mould. No longer considered fungi, slime moulds
Ben Hoare