Snorkellers approach an adult manatee at Three Sisters Spring, Crystal River, Florida. You might imagine that coming face to face with one of these enormous underwater mammals would cause some concern. However, the likelihood is that the rotund creature just wants you to scratch its belly while it floats around happily, as world-renowned underwater photographer Alex Mustard discovered. (Photo by Alexander Mustard/Barcroft Media)

M42 Subtle V1 cropped. One of the most well-known astronomical objects in our universe is the Orion Nebula and this image depicts the wider region of the Orion Molecular Cloud Complex that is its home. This complex also includes another popular target for astrophotographers, the Horsehead Nebula, as well as Barnard’s Loop and the Running Man Nebula, which can be seen to the left of this photograph. (Photo by Patrick Gilliland)

Highly commended birds : Crested guan by Tim Hunt (UK). ‘This photo shows a crested guan in the cloud forests of Costa Rica as it pauses while foraging on a lone branch. Due to the clouds that are so typical for this habitat, I could often only photograph the bird’s silhouette against a grey sky. But then, for a short moment only, the sun broke through the clouds, and I overexposed the image by over two stops in order to blow out the background and allow this beautifully marked bird to stand out’. (Photo by Tim Hunt/GDT European Wildlife Photographer of the Year 2015)

A photographer has shot this series of scenic selfies – scaling freezing mountain tops to snap himself in front of stunning scenery. Paul Zizkas breath-taking work features himself in front of beautiful backdrops such as shimmering lakes, snowy mountains and vibrant auroras. He has travelled to a number of different locations worldwide including Canada, New Zealand, Niue the South Pacific and French Polynesia. Explorer Paul, from Banff, Alberta, Canada, saw his selfies go viral early in 2014 – and has now unveiled his latest work. He said: I find that sometimes including a person in a landscape scene adds to the photograph – that it conveys a different story. Here: lake Minnewanka, Banff National Park, Alberta, Canada. (Photo by Paul Zizkas/Caters News)

“Guns have a massive amount of power associated with them. They are designed to kill. We decided to photograph portraits of them in a similar way you might photograph a powerful person. Like powerful people, pistols have this “perfect” quality that we wanted to explore. As we started shooting them, we could see flaws in their design. Metal burring around the barrels, scratches in the metal. This imperfection and detail were very interesting to us; connecting us back to these images as portraits”. – Peter Andrew. (Photo by Peter Andrew/Simon Duffy/Derek Blais)

“Asaro from the Eastern Highlands”. The mudmen could not cover their faces with mud because the people of Papua New Guinea thought that the mud from the Asaro river was poisonous. So instead of covering their faces with this alleged poison, they made masks from pebbles that they heated and water from the waterfall, with unusual designs such as long or very short ears either going down to the chin or sticking up at the top, long joined eyebrows attached to the top of the ears, horns and sideways mouths. (Photo and caption by Jimmy Nelson)

Nosy neighbour by Sam Hobson, UK. Sam knew exactly who to expect when he set his camera on the wall one summer’s evening in a suburban street in Bristol, the UK’s famous fox city. He wanted to capture the inquisitive nature of the urban red fox in a way that would pique the curiosity of its human neighbours about the wildlife around them. (Photo by Sam Hobson/2016 Wildlife Photographer of the Year)

Behaviour: Mammals category. Giant Gathering by Tony Wu, USA. Dozens of sperm whales mingled noisily off Sri Lanka’s northeast coast, stacked as far down as Tony could see. This was a congregation of dozens of social units, like a gathering of the clans. Aggregations like this could be a critical part of the whales’ rich social lives but are rarely reported. Some two thirds of the population was wiped out before commercial whaling was banned in 1986. This kind of major gathering could be “a sign that populations are recovering”, says Tony. (Photo by Tony Wu/Wildlife Photographer of the Year 2017)