It’s definitely a contender. Africa’s tallest indigenous tree – measuring a whopping 81.5 metres – has been discovered in a remote valley on the continent’s highest mountain, Kilimanjaro.

The colossus in Tanzania has matched Africa’s previous tree-height record established by a specimen of the introduced Sydney blue gum (Eucalyptus saligna) in Limpopo, South Africa, which died in 2006.

Andreas Hemp at the University of Bayreuth in Germany first spotted a bunch of tall Entandrophragma excelsum trees while exploring Mount Kilimanjaro’s vegetation 20 years ago. But it was not until recently that he and his team were able to measure their heights accurately using new tools.

They sized 32 specimens with laser instruments between 2012 and 2016, finding that the 10 tallest individuals ranged from 59.2 to 81.5 metres in height and 0.98 to 2.55 metres in diameter. Hemp estimates from growth rates that the arboreal behemoths are between 500 and 600 years old.

The world’s tallest trees are not normally found in Africa: for example, a 116-metre-tall sequoia tree grows in North America, and a 100-metre-tall eucalyptus in Australia.

This is probably a result of both a shortage of studies in Africa, so many trees are overlooked, and the fact that many of the continent’s tree species grow in places where limited resources prevent them from getting too tall.

The latter is not the case at Kilimanjaro, where a combination of nutrient-rich volcanic soils, high temperatures and precipitation have probably helped drive the growth of E. excelsum.

Supporting life

The massive trees play an important role in the mountain’s buzzing ecosystem, harbouring ferns and multiple other plants that grow on them for physical support. “They are like a city in the forest,” says Hemp.

But the green giants face the threat of illegal logging, which has plagued their precious habitat. The team therefore suggests that the valleys harbouring the giants be included in the neighbouring Kilimanjaro National Park for protection.

David Seaborg at the World Rainforest Fund in Walnut Creek, California, supports this view. He points out that protecting the trees could also allow us to preserve the abundance of plants, birds and insects that benefit from their presence.

Journal reference:Ìę Biodiversity and Conservation, DOI:

Read more: The secret of the world’s largest seed revealed;
Why trees can’t grow taller than 100 metres

It’s important to fit in. That seems to be the approach taken by this frogfish, which has turned white to match the bleached coral on which it is living.

Warty frogfish (Antennarius maculatus) are sedentary seafloor dwellers that can change colour over just a few weeks to seamlessly blend in with their surroundings. Their disguise renders them invisible to unsuspecting prey that they snatch for dinner.

Since the warm waters off the Maldives abound in vibrant-coloured corals, the frogfish living there typically match these orange or pinkish hues, says GabrielÌęGrimsditch of the International Union for Conservation of Nature Maldives in MalĂ©. But rising ocean temperatures have led to the widespread bleaching of these once-colourful corals.

When Grimsditch and his team were scuba diving in North Ari Atoll in May they photographed an unusual, white frogfish resting among the bleached corals. Its dark, protruding warts mimicked bits of brownish algae growing on dead parts of the coral skeletons. “We were very excited to see this,” says Grimsditch.

Frogfish rarely change location, so this spooky-looking individual had probably been in that same spot for a while, the team speculated. It is likely to have turned white as the corals were bleached in late April or early May, when ocean temperatures were unusually high.

Frogfish first

“It was fascinating because we had never seen a frogfish that had changed colour to become white because of a bleaching event,” Grimsditch says.

The team thinks this may show how these animals will react to these increasingly frequent events. It would be curious to see whether the frogfish would change colour again if the coral died and turned brown as it became overgrown with algae, Grimsditch says. “I would think it would – that would be my guess,” he says.

The fish’s adaptation to a changing environment recalls the famous peppered moth, which changed from being light to dark coloured during the UK’s Industrial Revolution.

“I just think it is fascinating,” says Caroline Rogers of the United States Geological Survey on St John in the Virgin Islands. “I think most people would be amazed to see that any fish could blend itself so remarkably.”

For John Parkinson at Oregon State University in Corvallis, the observation is a gloomy reminder of the longest-recorded global bleaching event, which has been hammering reefs since 2014. “It is another example of the sad state of affairs,” he says.

Crafty crows

Species: Sponge of the Rossellidae family
Habitat: Deep waters off Hawaii, US

Deep in the waters off the Northwestern Hawaiian Islands lurks a 3.5-metre-long behemoth – the world’s largest known sponge that could be hundreds, if not thousands, of years old.

Sponges are some of the simplest and most ancient of animals, though they don’t look like animals as we usually know them.

Large ones provide ecosystem services such as filtering seawater, recycling nutrients on reefs and providing habitat for other species, and are estimated to be able to live for more than 2300 years.

Daniel Wagner of the NOAA Papahānaumokuākea Marine National Monument and his colleague spotted the giant, a member of the Rossellidae family, during an expedition to the islands last year.

The sponge was filmed from two remotely operated vehicles during a dive on a ridge at the Papahānaumokuākea site – one of the world’s largest marine conservation areas, containing coral reefs that more than 7000 marine species.

Images of the sponge taken at a depth of just over 2100 metres revealed that it was 3.5 metres long, 2 metres high and 1.5 metres wide (see video below).

Its huge size trumps the dimensions of the sponge previously recognised as the largest – a colony of Aphrocallistes vastus with respective measurements of 3.4, 1.1 and 0.5 metres found in shallow waters off western Canada.

Rise of a giant

The stable, relatively undisturbed habitat of the conservation site has probably been conducive to the sponge’s unfettered growth.

“A lot of organisms in deep seas grow very slowly, so they need their habitats to remain stable over a long time to be able to grow larger and larger,” Wagner says.

We don’t know exactly how old it is. “Sponges don’t have things like growth rings that can be used to estimate age,” Wagner says. “We do know, however, that several coral species that live at those depths can live to multiple hundred to even a few thousand years: the oldest one is 4500 years. Thus, my best guess is that this is likely a very old sponge on the order of century to millennia.”

The discovery of the sponge at the site underscores the need to protect the area with strict conservation measures, says the team.

Sponges are thought to be some of the earliest animals to have evolved on Earth – perhaps even ancestors of all complex animals. They are also thought to have helped aerate ancient seas, boosting life in the oceans some 750 million years ago.

Most sea sponges feed on single-celled organisms, which they filter from water, but some are more voracious, catching small crustaceans.ÌęDolphins use sponges as tools to help them uncover food on the seabed.

Journal reference: Marine Biodiversity, DOI:Ìę

Read more: Sponge larvae: Your unlikely ancestors

Safari guide Onesmus Irungu witnessed and took photos of the unusual theft last year in Kenya’s Maasai Mara National Reserve.

He first saw a spotted hyena hunting and killing an adult topi antelope (above). Shortly after, a cheetah mother with her three 15-month-old cubs — one female and two males — approached the hyena and its breakfast. The cheetahs chased the hyena off the topi carcass before returning to feast on it (below).

Though cheetahs are known as top predators, finely adapted for high-speed hunts, this case shows they can occasionally put their legs to use to chase away the original owner of a kill and scavenge.

This behaviour is rare, says Femke Broekhuis, project director of the in Nairobi, Kenya, who co-authored the study reporting it together with Irungu. “It is inherently risky for a cheetah, especially one with cubs, to interact with larger predators such as spotted hyenas, as spotted hyenas are known to kill both cheetah cubs and adults,” they say in their paper.

The average body mass of an adult female cheetah is 36 kilograms, considerably less than an adult spotted hyena that can weigh up to 82 kilograms. Indeed, spotted hyenas are often implicated in the decline in cheetah populations, partly because they kill cheetahs and steal their kills.

But in this case, the lone hyena was probably a subordinate juvenile male that had dispersed to breed and was outnumbered by the gutsy, hungry cheetahs. “I think it is a fluke occurrence,” says of the University of Pretoria, South Africa. “It is probably just this perfect brew of things coming together that probably doesn’t happen often.”

Read more: Five wild animals that won’t do it in cages; When hyenas kill their own

Competing carnivore

Species: northern Pacific rattlesnakes ()
Habitat: stalks prey across much of western North America

It’s a premeditated attack. A deadly rattlesnake seems to be planning attacks by clearing a path for its strike in advance.

Northern Pacific rattlesnakes (Crotalus oreganus) have been filmed manipulating vegetation near the burrows of ground squirrels. It’s the first time they have been captured on video moving grass in such a way, says at San Diego State University in California.

Putman and her colleague Rulon Clark recorded two instances of hunting rattlesnakes pushing away grass around them at the Blue Oak Ranch Reserve in California’s Santa Clara County.

The snakes checked out the area for signs of prey and then, once they had identified a burrow, forcibly jerked their heads and necks to move surrounding grass (see video, below). The hunters proceeded to wait for their prey in an ambush spot for up to 3 hours.

[youtube]https://www.youtube.com/watch?v=hx_9OT3frpA[/youtube]

“Perhaps the snakes are modifying their habitat to try and increase their hunting success,” says Putman.

Problem solvers

One of the snakes was seen eating a ground squirrel later that afternoon, says Putman, but it’s not clear if the clearing behaviour played a role in catching the squirrel.

Two related hunting rattlesnakes, Crotalus viridis and Crotalus molossus, have previously been reported manipulating vegetation near prey burrows or runways.

“I think it points to some fascinating problem-solving behaviour,” says of the College of New Jersey in Ewing.

Birds and mammals are known to use clever foraging tricks, but most snakes haven’t been seen doing such things. “They’re just cool creatures that we take for granted,” Putman says. “They actually have behaviours that we once thought were only exclusive to mammals and birds.”

Journal reference: The Southwestern Naturalist, DOI:

Read more: Stunning fossils: Snake eating baby dinosaur; Extreme evolution: How snakes became the ĂŒber-eater

That’s remora

Pink whiprays

Piggyback rider

Looking good. Giant manta rays have been filmed checking out their reflections in a way that suggests they are self-aware.

Only a small number of animals, mostly primates, have passed the mirror test, widely used as a tentative test of self-awareness.

“This new discovery is incredibly important,” says , of the University of Colorado in Boulder. “It shows that we really need to expand the range of animals we study.”

But not everyone is convinced that the new study proves conclusively that manta rays, which have the largest brains of any fish, can do this – or indeed, that the mirror test itself is an appropriate measure of self-awareness.

, of the University of South Florida in Tampa, filmed two giant manta rays in a tank, with and without a mirror inside.The fish changed their behaviour in a way that suggested that they recognised the reflections as themselves as opposed to another manta ray.

They did not show signs of social interaction with the image, which is what you would expect if they perceived it to be another individual. Instead, the rays repeatedly moved their fins and circled in front of the mirror (click on image below to see one in action). This suggests they could see whether their reflection moved when they moved. The frequency of these movements was much higher when the mirror was in the tank than when it was not.

The rays also blew bubbles in front of the mirror, behaviour that Ari had not observed in the rays before.

“The behavioural responses strongly imply the ability for self-awareness, especially considering that similar, or analogous, behavioural responses are considered proof of self-awareness in great apes,” Ari says.

, of Hunter College in New York, says that it is interesting that manta rays did not show social behaviour towards the mirror image, as fish usually do. But she says it is unclear whether the rays actually recognise themselves in the mirror.

Curious behaviour

Jr, of the University at Albany, New York, who originally developed the mirror test, is also sceptical. The unusual movements in front of the mirror might have merely been a sign of curiosity or exploratory behaviour, he says.

Other studies have suggested that dolphins, elephants, monkeys and magpies, and even a robot, can recognise themselves in the mirror. But Gallup says these were usually conducted on just one or two animals and the results were not reproducible.

“Humans, chimpanzees and orangutans are the only species for which there is compelling, reproducible evidence for mirror self-recognition,” he says. This implies that self-awareness may be limited to humans and some great apes.

But Bekoff says that the mirror test may not be the litmus test for self-awareness in all animals. It is a visual measure, so it might not work in species that navigate their worlds primarily using senses other than vision. Such species may fail the mirror test, but they may still be self-aware, Bekoff says.

He thinks it is time to raise the bar on the way we study self-awareness in animals, including manta rays.

“It would be nice if someone could do neuroimaging while these animals are doing something in response to seeing a reflection,” he says.

Journal reference: Journal of Ethology, DOI:

Read more: Hey! good looking

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