The discovery of a colony of large fish-eating spiders in a Swansea canal has excited nature experts.
The fen raft spider positions itself to 'fish for its prey'
Countryside Council for Wales spokesman David Painter said: "Up until now, the fen raft spider was only found at UK sites, both in eastern England.
"Finding a population of this size in Wales is extremely good news," he said.
Michael Clark, of the South and West Wales Wildlife Trust, first discovered an adult fen raft spider on weeds that were floating on the Tennant Canal at Pant-y-Sais, near Jersey Marina, making this the first Welsh record of this rare spider.
Since this first discovery, more than 20 spiders have been found, some of them with young.
The fen raft spider has a black or brown body nearly an inch long, white or cream stripes down its sides and hairs on its legs that allows it to glide across the water's surface to grab prey.
Its name comes from the way it leans over pools on a plant and dangles its front legs on the waters' surface to pick up vibrations from approaching prey - mainly pond-skaters and dragonfly larvae.
Fishes for prey
It can even catch small fish such as sticklebacks as well as tadpoles.
Mr Painter, CCW's Warden for Crymlyn Bog and Pant-y-Sais Fen, said: "This is a exciting find.
"Up until now, the fen raft spider was only found on two sites throughout the UK - both in eastern England. So, finding a population of this size in Wales is extremely good news.
"It is extraordinary that such a large spider has not been noticed before!
"We will now start to survey the site and other similar sites in the area - including Crymlyn Bog - and we expect to find more.
There are about 36 trillion spiders in the UK
That's about 600,000 spiders for every person in the country
And about 150 spiders for every square metre of land
"The canal has been traditionally managed by the Tennant Canal Company who have helped us survey the area for new sightings of this rare spider."
This endangered species was first discovered in 1956 and has long been thought to be restricted to two sites at Lopham and Redgrave Fens on the border between Suffolk and Norfolk and the Pevensey Levels in Sussex.
It is protected under the Wildlife and Countryside Act 1981 and is thought to be under threat of extinction in western and central-southern Europe whilst remaining well established in Scandinavia and the Baltic States.
CCW is the Government's statutory adviser on sustaining natural beauty, wildlife and the opportunity for outdoor enjoyment throughout Wales and its inshore waters.