It's Springtail Time Again!

08th November 2013
Well, the vast majority of bees are now inactive so it's time to turn to one of my other photographic favourites; springtails. There are three Orders of the Collembola (springtails). The Entomobryomorpha and the Poduromorpha are elongated in form, and the Symphypleona are globular. It's the globular springtails that particularly interest me.

The globular springtails that I see locally, vary in size from around 0.4mm to 3.0mm. Most days I try to spend some time in my local churchyard looking for them in leaf-litter. This one; Sminthurinus aureus is quite common locally at the moment. The Sminthurinus springtails are typically 1mm long or less and vary considerable in colour and in pigmentation patterns. There is actually a Sminthurinus 'aureus-group' that includes black, brown or yellow body colouration. This yellow colouration seems the most common. The darker lateral markings are not uncommon. The pale greenish dorsal colouration is caused by the gut content colour showing through.

This individual with very dark lateral, longtudinal bands is Sminthurinus elegans. The UK literature suggests that this species is generally found in slightly drier areas than Sminthurinus aureus, but I'm finding them both in the same places. There's uncertainty as to whether all the main colour forms represent different taxa or are just colour variations of Sminthurinus aureus. Genetic studies will no doubt sort this out in time. In the meantime, I'm content to just find and photograph as many colour forms/variations as I can!

This individual is interesting. I've seen quite a few like this. The dark body colour and pale head (together with some other abdominal details) suggest that it is Sminthurinus igniceps. The literature notes that there have been only a scattering of reports of this species in the UK, usually in glasshouses or environments protected from frost. Whatever, this is a most attractive springtail and one that I have not seen before. It would need detailed microscopical examination to confirm the species.

Just in case you are not familiar with the anatomy of springtails, this upturned individual (that has "sprung" and landed in moisture) shows a couple of interesting features. Although six-legged they are not insects, but are in a separate class of the Arthropoda. Two distinguishing features are the furca and the collophore (or ventral tube). The furca is a two-pronged appendage that is visible in the photograph. It is usually held in tension under the abdomen but when released, propels the springtail into the air. A useful escape mechanism.

The ventral tube has the ability to extrude two long vesicles. The whole mechanism is involved in osmo-regulation and for self-righting. Two partially-extruded vesicles are visible in the photograph. In case you are worrying, the springtail did manage to right itself and walk off!

The smaller globular springtails (around 0.5mm) are just visible with the naked eye but the larger ones are reasonably easy to spot. If you have a hand-lens, turn over fallen leaves and give them a scan or look on low vegetation or fallen bark and branches. It's a fascinating world and one that can provide a lot of interest through the autumn and winter months. Also keep a look out for psocids (barkflies), tiny predatory wasps, harvestmen, spiders and lots more!

[Click on any image for a larger version]

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