Pauropods are lovely in the way that a spaniel puppy is, waiting to be thrown a stick. For something so small, only collembolans have the ability to elicit the same happy feelings from me when I watch them.
They have an unusual gait, more of a funny, joyful scamper than a walk.
Even being so small, the way they move is so distinctive, that without a hand lens, they can easily be picked out in a line up from similar sized millipedes. They run for a couple of seconds before stopping dead. Then after a quick, inquisitive twirl of their antennae, they run off in another direction. They're usually under 2mm, although one tropical family can get up to 5mm. They all have branched antennae, a defining characteristic for all the group.
They're sightless and don't have a heart.
When freshly hatched, baby pauropods have three sets of legs, increasing up to eight, nine, ten or eleven sets depending on genus. Most of the literature talks about them looking initially like centipedes which seems bizarre, if you've ever seen a centipede. Apart from having quite a few legs and often being sausage shaped, pauropods seem very different.
They are a member of the Myriapoda, and presumed to be a sister group to the millipedes, although even this is disputed. They certainly share some common attributes, but their differences are also large.
In 1873, John A Ryder, an American naturalist, described the difficulties even initially trying to fit the Pauropoda into a one single group.
'In the form of the body and legs the creature recalls the large carnivorous myriapods or centipedes, whilst in the possession of a pulvillus or pad, and a claw on the feet, they resemble in a measure true insects; in their branched antenna they resemble crustaceans and in their herbivorous habitats they resemble the herbivorous, and in the distribution of the legs they combine characters of both the herbivorous and the carnivorous myriapods.'
There's no other word for it. pauropods preen. The antennae are lifted out of the way before they start to delicately nibble at their feet. I've never seen them do any other part of the body... The photo above was taken in Somerset, UK, below, from near Tairua, New Zealand.
And then, if that wasn't enough, One from Germany and another from Mexico. It's a very popular pastime for pauropods.
Above is a short video, taken on my phone. It shows the erratic movements of a typical pauropod quite nicely.
Three species from the UK.
Eirmopauropus species- 1.25mm
Eirmopauropus species- 1.25mm
Above is a member of a new family of sclerotised Pauropoda from New Zealand, the Eirmopauropodidae. So far there has only been one species recorded, and this chap from Stewart Island has a different pattern of sclerification so is probably a new species.
Continuing the sclerotised pauropod theme, The pauropod above, and the juvenile below are from Kuranda, in the wet tropics of Queensland, Australia. The plates are very distinctive in this species.
Then there is this chap, from Binna Burra, Lamington National Park, Queensland, Australia. As an adult, the darkest coloured pauropod I've ever seen, almost purple brown under a magnifying glass. The sclerotised plates are so pronounced, it almost looks like the missing link between the Pauropoda and the Eurypauropodids....
Below is a large juvenile of the same species.
The Eurypauropodidae were first named and described by John A Ryder in the October 1873 edition of The American Naturalist. This was only thirteen years after the first pauropod had been described by Lubbock in London and designated its own class and order of Pauropoda. It makes fascinating reading. At that time, only three species of Pauropus had been described by Lubbock. Even now, 140 years later, Ryder's exuberance and ill-contained excitement is palpable as he gets to announce to the world that he has just discovered a fourth pauropod. And one completely unlike any seen before. Not just a new species and new genus, but a new family.
And they are even harder to find than usual. Not only are they under 1mm big, they're often the same colour as the soil. Their plates are fully sclerotised, where each of the fused pairs of tergites on an adult has 'hardened'. They tend to be a little slower and less manoeuvrable than other pauropods as a result. The photo above is a New Zealand species from the North Island, as are the next two photos of another species, directly below. The patterning is very distinctive on the latter and strangely reminiscent of the Roger Burrows' Altair designs from the 1970s.
first discovered in 1982
first discovered in 1982
Trachypauropus britannicus was the first species of Pauropoda I ever saw and it took a while to track down what exactly it was. It's the UK's only eurypauropod, first described in 1982. As is almost always the case, the soil fauna are less known and less understood than a lot of other, more accessible animals. As it is, we know very little about the pauropods. It's certainly likely that they eat fungal hyphae and soft, rotting matter, though some have such poorly developed mouthparts that they are probably fluid feeders. Worldwide, at this time, there is only one taxonomist and authority on world Pauropoda- Ulf Scheller. For such an engaging little animal, it's a great shame they're not more popular amongst biologists.