A load of old Balanus

We're all familiar with barnacles, at least in broad terms - we see them on rocks, ships, whales etc, they turn up in A-level college biology projects, and if we slip on them, they are sharp and they hurt. However, how often do we really look at them?

A typical view of a barnacle-encrusted rocky shore (Start Point, south Devon, England)

They are of course crustaceans (of the class Cirripedia, order Thoracica) and come in three main forms, the suborders Lepadomorpha (the stalked 'goose' barnacles), Verruomorpha (like 'typical' barnacles but with only two opercular plates - I'll get on to that later), and Balanomorpha (the 'typical' barnacles'). I'm only going to focus on the latter, though I can't let the opportunity pass by without mentioning the existence of the order Rhizocephala. These are evolutionarily derived relatives of the barnacles and parasitise decapod crustaceans (such as crabs), their free-swimming juveniles settling on their hosts and developing into an 'interna' of root-like growths and an 'externa' which is a sac of reproductive parts. They lack as body as such, and their name means 'root head', and as with many internal parasites, they redirect their hosts' physiology and behaviour to their own ends. If I find any, I'll definitely write about them, but until then, here's a fine little 4-minute video introducing their life cycle through the medium of hand-drawn cut-out animation.

Anyhow, back to barnacles as we know them... The rocky shore above was well encrusted with barnacles of several species. There were many of the small limpet-shaped ones (such as Chthamalus stellatus in the family Chthamalidae), but what grabbed my attention were some larger, less flattened specimens typical of the the family Balanidae.

A barnacle of the family Balanidae.

As you can see, this barnacle is fairly tall (rather than being a low flat cone). Although the joins are rather obscured in this mature specimen, there are six plates forming the outer wall. It isn't clear from the photo, but the base forms a calcareous layer on the underlying rock (rather than a membranous layer) and hence this is in the genus Balanus. Identification past this point is a little tricky because the colours are so variable and corrode to a greyish mishmash in old specimens, but the obscure sutures, sharp 'beak' (tergum) and ribbed outer surface suggest either B. perforatus or B. balanus.

The scutum (seen here as a 'keel' beneath the sharply beaked tergum) is slightly saw-edged, and the smaller barnacles (which I assume are the same species) below the large one have yellowish rims with brown banding below/around them. Also, the opening in the large specimen isn't especially small. These features combine to suggest that this is B. balanus - a common species although south Devon is at the very SW extent of its range as it is absent from Cornwall, but is a place where this species has been regularly recorded. A closer look should also help clarify a couple of the features mentioned here.

The operculum, tergum and scutum of Balanus balanus

Aside from the smaller barnacles that are using it as a substrate, the beaked tergum is clearly visible as is the rough, serrated edge of the scutum. Both these structures are paired (you can see the join at the top of the tergum), forming four internal plates (collectively the 'operculum') that can move and open to allow the feeding structures (feathery 'cirri') to waft in the water and catch food particles.


So, a closer-than-usual look at a familiar organism - and a relatively rare (for me) foray into marine and littoral/intertidal habitats. Maybe I'll have to do more on this as it was the habitat that first grabbed my attention in terms of the invertebrate fauna...

What's in a wall?

As you might imagine, I don't mean bricks and mortar - instead I am more interested in the species that can be found growing on walls, particularly old rough stone walls in areas with low levels of air pollution such as might be found in the village of Slapton in south Devon. Yup, where I was one holiday a couple of weeks ago... Old walls are well known to be important for wildlife - for instance, lizards can often be seen basking on them - but for those of us living or working in cities, especially with relatively new and smooth-surfaced buildings (and more air pollution), the opportunities to see such species can be limited.

Some are so strongly associated with this type of habitat that their common names reflect it, such as the wall pennywort Umbilicus rupestris (the generic name reflects its other common name, 'navelwort'). Like many wall-dwelling species, they are also found on natural rocks, but man-made rocky surfaces can be just as good.

The round leaves of wall pennywort Umbilicus rupestris.

You can see pale green lichenous growth here, but a closer look around this wall revealed a somewhat more impressive display - the little trumpet-like fruiting bodies of the lichen Cladonia (one of several similar species).

A cluster of Cladonia

There were also larger growths of non-lichenous fungi among the damp, mossy hollows. One was the branched and spindly Grey Coral Clavulina cinerea. This is a common species but being associated with the ground in woodlands, might not seem a likely wall-colonist. However, the crevices were full of moss and soil, and roots were present from the woody plants on top of the bank the wall retains. So, from the fungus' point of view, just like home! Another was an attractive orange-red waxcap Hygrocybe sp., possibly H. helobia which was only described scientifically in 1974 and is more often associated with grassy woodland clearing or heaths (but again, conditions are suitable in this wall). However, without closer examination (beyond what I'm likely to do on holiday), the species-level ID remains tentative.

Grey Coral fungus Clavulina cinerea

Waxcap Hygrocybe sp.

Moving through the major taxonomic groups, there are also ferns associated with walls. One of these is the rustyback Asplenium ceterach which I initially thought I had found; however, closer examination (yes, sometimes even on holiday, though it took iSpot to confirm it as I don't ID ferns very often...) showed it to be A. adiantum-nigrum, though both are common in SW England. Another (which I can also find growing from crevices in the walls of the church near where I live) is the maidenhair spleenwort A trichomanes.

Asplenium adiantum-nigrum (upper surface of fronds)

Asplenium adiantum-nigrum (lower surface of frond showing red-brown sori)

Maidenhair spleenwort Adiantum trichomanes

Lastly I want to return to the flowering plants, this time a non-native garden escape Nerine bowdenii, also known as the Guernsey Lily. This southern African species is a popular plant in the village of Slapton and can be seen along the narrow lanes outside many of the cottages. However, coming from mountainous areas, it too can adapt to 'mural' life and at least one had managed to escape through a garden fence and grow on top of the old stone wall featured here. I could continue - after all, with all these plants, fungi and lichens, there are of course many invertebrates (my usual topic!) - however, as I promised my wife I would not spend the week rummaging around with collecting pots, these will remain mysterious for now and I'll simply leave you with the big pink lily which, although appearing delicate, was clearly capable of surviving repeated buffeting by passing vehicles...

Guernsey Lily Nerine bowdenii.

No seeds, no fruit, no fungi - November!

It's been an odd year in the UK (and elsewhere) - an unusually warm early spring, then a cold, wet early spring and summer and a very variable autumn with frosts and warm periods. Unsurprisingly, this has seriously impacted some of the UK's wildlife negatively. For example, the Big Butterfly Count found declines in many common species, with 11 of the 21 target species decreasing in abundance by more than a third since 2011. There are a number of reasons - low temperatures clearly affect cold-blooded groups such as insects, which in turn reduces the food available for insectivores such as birds and bats. Plant growth is also affected by cold and water-logging, so less sugar is produced, fruit growth is reduced (and what does grow may be affected by moulds and blights and fall early or rot on the plant), leading to less seed production - bad for plant reproduction and seed-feeders such as many winter birds. This is already having visible effects as more unusual species appear in gardens - so, it is even more important to keep bird-feeders full. Poor fruit/seed growth in Scandinavia has already meant that at least a couple of thousand waxwings have flow across the North Sea to NE Britain. There are also less obvious effects. For example, the reduced sugar production means that ectomycorrhizal (externally root-associated) fungi grow poorly despite the damp conditions.

However, not all is doom and gloom. Some species have taken advantage of warm late summer and autumn temperatures to grow and breed - I have certainly seen late bird-nesting activity, and while in south Devon last week (the SW is the warmest part of the country), while some trees were losing their leaves, others were budding as seen here.

Hazel coming into bud in mid-November in south Devon

Late flowering has provided at least some extended nectar availability (apart from ivy which is always a winter source) as seen here where a small Panurgus calcaratus bee is feeding on a yellow composite flower, again in mid-November. Found in a band across SE England it is also known all round the SW coast as you can see on the map here; clearly a species needing warm temperatures as it is absent further north.

Panurgus calcaratus feeding on a yellow composite flower in warm sunny mid-November conditions in south Devon

Warm damp autumn weather has meant that some fungi have done well eventually, such as those living on damp deadwood and leaf-litter, while in our new garden pond, the pond-skaters have bred very successfully and are highly active. Slugs and snails have also had an excellent year, though this is not popular with gardeners and allotment-holders, not to mention those of us with old houses that have little holes where slugs can gain access in the middkle of the night...

Overall, there are sadly probably more wildlife losers than winners, but what does the future hold? Well, nothing is certain, but an important study by Overland et al. (2012) does give some indications. Firstly, as many people have suggested, it isn't just 2012 when the summer has been cold and wet - this is a pattern that seems to have begun in 2007 when there was what appears to be a sustained shift in early summer Arctic winds. This change is linked to increased North American atmospheric blocking which ultimately leads to the southward movement of the jet stream that has been mentioned in TV weather forecasts. The study also looked at why this has happened and has unsurprisingly concluded that climate change is a likely candidate - in particular the melting of Arctic ice (particularly around Greenland, remembering that Greenland is politically European but geographically North American) which highlights the potential connectivity between Arctic climate and mid-latitude weather i.e. the Arctic heats up, the UK gets bad summers.

This is of course an ongoing story - research is undoubtedly ongoing to finesse some of the findings and explanations. As an academic, I find this fascinating but as someone interested in wildlife and environmental issues, I also find it deeply troubling, especially when the UK government seems to be trying to pull back from its low-carbon committments. However, I'll stop there lest the Ecology Spot becomes my political ranting zone!

Reference

Overland, J. E., Francis, J. A., Hanna, E. & Wang, M. (2012). The recent shift in early summer Arctic atmospheric circulation, Geophysical Research Letters 39, L19804 (6pp.)

Cocoons of woolly doom

Back in the day, wardrobes and blanket-boxes smelled of mothballs (largely naphthalene though it was flammable, and camphor is a less toxic alternative) placed to keep fabric-eating moths of the family Tineidae away. Now, they are less common as the moth larvae do not eat synthetic materials, and on the whole houses are cleaner and more hygeinic. However, in forgotten cupboards, they still nibble their way through wool and other animal materials such as furs. The adults tend to be rather drab, but as I found out while clearing a cupboard of woollen items in the attic, the larvae of one species, Tinea pellionella, the case-bearing clothes moth can produce something rather colourful (if also annoying) - their cases or cocoons.

A larval case of Tinea pellionella

The larval case above is clearly made of fibres spun from differently coloured wools (the ones with the holes in...) and in its own way is quite a beautiful thing. It is dorso-ventrally flattened, and the ends are open; thus the larva's front end can protrude to allow feeding and faeces can be ejected (the rear is bottom-right and shows small dark faecal pellets). The moth pupates in the case which is fixed some distance from where it feeds and then emerges, leaving the empty skin protruding. The group as a whole can be difficult to identify, often requiring dissection of adults.

A case of T. pellionella with protruding skin after emergence

Having found (and squashed, sorry) quite a number of these, I hope that I won't need to sew up any more holes - fortunately I'd noticed a few adults flying around and realised that the larvae needed to be found; so, with  a bit of luck the infestation will remain minor, and I'll be off to buy some cedarwood repellent, though the number of dried husks also indicated that our house-spiders were doing a useful job!

A smaller, brighter case of T. pellionella.

Further reading

Heath, J. & Emmet, A.M. (1985). The Moths and Butterflies of Great Britain and Ireland. Volume 2: Cossidae - Heliodinidae. Harley, Colchester. [Part of the impressive (but sometimes expensive) MBGBI series covering all Lepidoptera of the British Isles in considerable detail, including dissection of genitalia]
Palmer, R.M., Porter, J. & Collins, G.A. (2012). Smaller Moths of Surrey. Surrey Wildlife Trust, Woking. [Distribution maps for the county of Surrey, but much information which is more widely applicable]
Stirling, P., Parsons, M. & Lewington, R. (2012). Field Guide to the Micromoths of Great Britain and Ireland. BWP, Gillingham. [excellent affordable guide]

Leaf beetle key - write, edit, plug

If you are a regular here, you'll know that I have a considerable interest in invertebrates and that they form a large proportion of the topics I write about (a glance at the 'tag cloud' in the right margin will confirm that). However, you might not know that I specialise a little more than that and that one of my areas of specialism is in the Chrysomelidae - the 'leaf beetles', which include the 'seed', 'reed', 'flea' and 'tortoise' beetles - and the two small closely related families, the Orsodacnidae and Megalopodidae. You may be familiar with these groups having a slightly different taxonomic arrangement, such as the Bruchinae being accorded full family status, but recent cladistic work (e.g. Reid, 1995) suggests otherwise.

A few years ago I became interested in this group as a voluntary species recorder for the UK's Biological Records Centre (BRC), and later as organiser of the related UK Recording Scheme. I soon found that, even with the excellent Atlas to British and Irish species having been published (Cox, 2007), I needed to collect a large number of individual journal articles in order to be able to reliably identify adults of the British chrysomelid fauna and that even then there were gaps. The last key covering all species was Joy (1932) which, although excellent, was unavoidably out of date (and hard to find affordably until the CD-ROM version appeared), while the update (Hodge & Jones 1995) was out of print. Grr. Although the BRC were extremely helpful, sending me copies of the articles I needed if they had access to them, it became clear that a lack of readily available user-friendly identification literature was a major barrier to expanding interest in this beetle group. Such a barrier needed to be overcome, especially as the Chrysomelidae includes many charismatic (shiny, colourful and metallic such as the green dock-beetle Gastrophysa viridula) species as well as a number of considerable economic importance (horticultural and agricultural pests) such as the unpopular Lily Beetle (Lilioceris lilii) and the notorious potato pest, the Colorado Beetle (Leptinotarsa decemlineata) although the latter is currently unable to colonise Britain due to low winter temperatures. There is also a conservation component as accurate identification is needed to provide useful distribution and monitoring data. For example, there are a number Biodiversity Action Plan (BAP) and Red Data Book (RDB) species, such as the Pashford Pot Beetle Cryptocephalus exiguus which provides an (unfortunately) excellent case study of ineffective landscape-scale conservation, while the flea beetle Psylliodes luridipennis is a UK endemic known only from Lundy Island where it is threatened by over-grazing and invasive rhododendron.

Consequently, I made the decision that 'the book' would only appear if I wrote it, and so I began, aiming for an intermediate audience as I wanted to cover all British and Irish species, and many require dissection under a low-power microscope - not something for beginners maybe... I won't go into too much detail other than to say it was difficult - really, really difficult. The initial draft wasn't too bad to write, but - as expected - had many errors and omissions which were discovered during testing. However, many testers provided excellent tips and suggested changes - some extensive - which greatly improved the final version. The difficulty came where species were not covered reliably by existing literature, and this happened a lot while trying to write keys for the notoriously tricky flea beetle genera such as Longitarsus. I was aided in many cases by the excellent images (including genitalia) on the European Chrysomelidae website, but in the end there is no substitute for going to a museum or other institution, and consulting specimens in their reference collections such as those held in Winchester (Hampshire County Council), Oxford (Oxford Uni Museum of Natural History) and at the BENHS HQ near Reading. This is what sampling and collecting is for - it ain't decoration or 'train-spotting'!

A tray of beetles from the Oxford Uni MNH collections

So, after editing, re-editing, adding a few species that had been newly found in Britain, and making changes following taxonomic updates, the final version - complete with cover photo - went off to the publisher and then the printer. I was expecting it to be ready in mid to late November, but - much excitement - a courier delivered a box of my author's copies this morning - whoop! I think they are great (obviously) and a bargain at only £8.50 - available here - enjoy! All the many many hours of beetle-scrutiny was worth it - now, I seem to remember there's no general textbook covering this family...

Woo hoo! A box of brand new copies of my key to British and Irish leaf beetles.

References

Cox, M.L. (2007). Atlas of the Seed and Leaf Beetles of Britain and Ireland. Pisces, Newbury.

Hodge, P.J. & Jones, R.A. (1995). New British Beetles: Species not in Joy's Practical Handbook. BENHS, Reading.

Joy, N.H. (1932). A Practical Handbook of British Beetles (2 vols., 1976 reprint). Classey, Faringdon.

Reid, C.A.M. (1995). A cladistic analysis of subfamilial relationships in the Chrysomelidae sensu lato (Chrysomeloidea). In: J. Pakaluk & S.A. Ślipiński (eds.) Biology, Phylogeny, and Classification of Coleoptera: Papers Celebrating the 80th Birthday of Roy A. Crowson. Muzeum i Instytut Zoologii PAN, Warsaw, pp. 559-631.