Haematoccus algae

I am an amateur naturalist trying to learn a little about everything living in my garden.

Recently, in the interests of finding some life-form with which to entertain the legions of avid readers of this blog (hem, hem), I decided to investigate what life might exist in a small pool of rainwater that had collected in the crevices of a sheet of polythene lying in my garden. Putting a drop under my hobbyist's microscope I was immediately confronted by large numbers of the creature seen in photo 1 (scale:1 small division = 1um). Some were motionless. More excitingly, others were highly active, 'zooming' through the water at a rate of knots (see later)

Some internet searching later, and with the help of photo's such as those on Ralf Wagner's microscopy site, and I'm tolerably confident I'm looking at a Heamatoccus alga.

The red colouration, motile behaviour and the presence of the transparent, gelatinous envelope surrounding the central green body all fit with the the species being H. pluvialis on this site ('Algaebase') . I don't claim any certainty over this identification however, since firstly I'm no expert, and secondly the same site lists 5 other species in the Haematoccus genus and a staggering 123,336 species of algae overall.

The family Haematoccae is part of the Volvocales order of algae, one example of which - Volvox - is a perennial favourite with microscopists. The Volvocales are equipped with two whip-like flagella - the secret to their ability to 'swim' through the water. The length and positioning of any flagella on an alga is an important aid to identification. Unfortunately the quality of my camera/microscope optics doesn't appear to be good enough to have caught these in the (dormant) Haematoccus specimen in photo 1 (or is it that flagella are lost in the dormant state?) - but the superb photo's by Wim van Egmond here show them clearly.

In researching the life in my garden I constantly come across what I imagine at first to be 'obscure' creatures. "Beyond naming it, surely no-one can have found the time to learn anything interesting or remarkable about this little critter!" I think to myself. It's a constant source of enjoyment to me to learn I'm wrong, and that for just about anything I come across, someone somewhere will have discovered some remarkable or interesting 'story' (which isn't to say that vast amounts don't remain unknown about the natural world of course).

So it was with H. pluvialis. Beyond a few dry descriptions in an obscure journal, surely there would be nothing say? Wrong again! It turns out H.pluvialis is an algae of significant commercial importance. It produces the highest known concentrations of astaxanthin of any living creature and is cultured on a commercial scale. Astaxanthins are chemicals used in the cosmetics, food and feed industries. They are antioxidants and have been studied for their potentially beneficial effects against everything from cataracts to colonic cancer. Guerin et.al. have produced a review (Trends in Biotechnology, 21(5), 2003). Astaxanthins are cartotinoid chemicals responsible for the red coloration in photo 1. They act as a 'sun block' against harmful UV rays. Those dormant algae I observed in my microscope sample seemed to contain more red pigment than mobile ones. I assume this is because dormancy is, in part, a mechanism to survive in dry conditions when cells can expect to need more protection from the sun.

Algae introducing astaxathanins into the food chain is the reason why animals higher up like shrimps, salmon and flamingos end up with pink flesh or feathers.

Returning to the issue of the mobility of H.pluvialis, Burchardt et.al (Biodiv. Res. Conserv. 1-2, 163-166, 2006) give a figure for their swimming speed of 200m/h. Given that their size is about 20um, scaling this up, and assuming a human about ~2m tall and I've got my maths right, this corresponds to a person swimming along at 20,000 km/h!

Finally, I can't end without mentioning one of the few books I have that gives a fairly detailed introductory guide to freshwater algae, namely Freshwater Microscopy by W.J. Garnett. Though it contains no real information about Haematoccus beyond a mention, it covers many common UK species in some detail. First published in 1953, I particularly like dipping into it for its evocation of a seemingly quieter more 'holistic' (for want of a better word) world, before out-of-town shopping centres and a life of frenzied commuting up-and-down packed motorways, when armies of amateur hobbyists seemed to spend their evenings and weekends learning the art of painting watercolour landscapes, investigating the geology of their county, or studying the lifeforms in their village pond. Or perhaps that's rose-tinted nonsense, though I do wonder how many hobbyists there are today, who, of a typical weekend, boil hay in rainwater in order to culture pond protozoa for study as Mr Garnet advises!

On the other hand I may be entirely wrong and there are legions of you hay-boilers out there! If you're one such, do leave a message to say hello.

Common Pheasant Phasianus colchicus

I am an amateur naturalist trying to discover everything living in my garden.

Handsome fellow isn't he! Photo 1 shows one of two male Common Pheasants (Phasianus colchicus) that visited my garden recently. Living as I do in rural Oxfordshire, meeting one isn't unusual; their rearing and shooting is common hereabouts.

The RSPB estimates there are 1.8million breeding female pheasants in the UK.

From a search of the internet a few random facts I've turned up about pheasants include some evidence that pheasants are sensitive to noises beyond the range of human hearing (Stewart, The Ohio Journal of Science. v55 n2 (March, 1955), 122-125). Secondly, given a choice, the 'stuff' (sand, loam, straw, feathers...) in which an adult pheasant will choose to take a dustbath can be predicted ahead of time by noting the material a bird prefers to peck at when still a chick (Vestergaard&Bildsoe, B Acta Vet. Brno, 1999,68, p141). This may seem an esoteric piece of knowledge, but as anyone who has ever watched a documentary about battery chickens will know, feather plucking is a damaging problem among livestock birds under confined conditions and an understanding of pecking behavior in birds can have worthwhile commercial implications.

The Common Pheasant is native to Asia. Like the peacocks, the Common Pheasant is an example of a sexually dimorphic species - a species in which males and females show consistent difference in form. Male pheasants are brightly coloured; Females are cryptically camouflaged. Photo 2 shows a female I spotted lurking in my garden shrubbery early last summer.

Sexual dimorphism is a much studied topic in the theory of evolution. Scientists would like to understand more deeply what forces encourage it and what advantages follow.

An internet search led me to a number of papers on sexual dimorphism in pheasants but unfortunately most were on the pay-to-view sites of commercial publishing firms. This always irritates me as it's typically you and I, the taxpayer, that has paid for the research contained in these papers. To be asked to pay again to read the results seems a bit much! Anyway, I did manage to find a few freely available papers from which I learn that female pheasants choose male mates based, in part, on the length of their spurs. Studies have shown spur length to be an honest indicator (see my peacock posting) of male health - males with longer spurs really do seem to be fitter than less well endowed males.

Spurs are a secondary sexual characteristic - a characteristic that differs between the sexes.

Girl pheasants also appear to judge their men folk according to the quality of their wattles (the red cheek patches in photo 1). Smith et.al. provide one study of this. My (amateur) understanding of their work is as follows:

Biologists had previously worked out that certain 'carotinoid' chemicals were associated with coloured appendages in some animals. At the same time, animals getting a good diet were known (perhaps unsurprisingly!) to have stronger immune systems than poorly nourished specimens. Smith et.al. wondered whether carotinoids were the root cause of both i.e. whether both the strength of a male's disease immunity and their wattle quality were directly controlled by the amount of carotinoids in their diet. If so, this might provide a very natural explanation of why females have 'a thing' for wattles -good wattles would be an honest indicator of the disease resistance of a suitor.

And the answer...after a series of detailed experiments Smith et.al. found no such correlation! Back to the drawing board in terms of discovering the deeper explanation of what's going on, but a nice example for those who might question whether science isn't ultimately a process of rigorous enquiry.

A lichen Aspicilia calcarea

I am an amatuer naturalist trying to discover what lives in my garden.

Those following my recent posts will know I have been on something of a mission to blog the lichen-life on the exterior of my house. Photo 1 shows yet another inhabitant - another crustose lichen (for those unfamilar with lichens, see my post here).

Incidentally, photo 1 also captures (upper left) our old friend, the moss, Tortula muralis.

After a little research I'm confident the lichen here is Aspicilia calcarea. Characteristic features include the cracked, white thallus (the main body of the lichen) and the irregularly shaped apothecia (the black, spore-liberating cups) sunk into the thallus. The books tell me that A. calcarea is common on hard calcareous walls etc. in lowland Britain. Photo 2 shows a closeup.

For those wanting a cheap photographic key to some common, British, urban lichens incidentally, I recommend the short-form guide sold by the good people of the Field Studies Council . For something more detailed the book Lichens (Frank S.Dobson) is especially good.

I'm fond of lichens. Their ability to shrug off the worst the elements can throw at them gives them, for me, an appealing minature 'feistiness' - I picture them squatting on exposed boulders on windswept mountain sides goading the rain "Come on! Give me your best shot! Is that all you've got pal !?"

On a more rational note (!), something that intrigues me is the diverse array of colours and shapes lichens adopt. I have no deep expertise in evolutionary ecology but as I understand it, there is nothing haphazard about the forms taken by species. Life is hard and an ever-present scarcity of resources and the threat of predation and disease is a constant imperative, forcing species to individually specialise in unique methods of suvival. A famous example is of course the beaks of finches, with different species having been driven to evolve different beak-shapes to allow them to eat different nuts and seeds. Different birds evolving different beaks to help them occupy different feeding niches is one thing. The distinct environmental pressures or purposes that drive two lichens such as A. calcerea and C. citrina to adopt such different colours and (once you look closely) really quite different textural forms, when both seemingly occupy the same ecological niche of lowland stone (indeed, the same household windowsill in my case!) - I struggle to guess. Do leave a comment if you can help me.

European Hornet Vespa crabo

I am an amateur naturalist trying to learn something about everything alive in my garden.

Photo 1 (click to enlarge) shows the handsome insect I found lying dead on a windowsill in my house some months ago. I am not expert at insect identification so at first I wasn't sure what I was looking at, but a little internet browsing and I'm confident I've found a European Hornet (Vespa Crabo): of the half dozen-or-so social wasps one might encounter in a British garden, the hornet is the only one with a distinctly brown coloured thorax. Much the most extensive introductory source I've come across online is Dieter Kosmeier's excellent hornet website.

Despite their fearsome reputation hornets are no more likely to attack humans than other wasps, nor is their sting notably worse. They are voracious predators of other insects however; a nest colony can take up to half-a-kilo a day. There are even records of hornets taking down pairs of copulating dragon flies (see Dijkstra et. al., Int. J. of Odonatol. 4(1),17-21, 2001).

Queen hornets hibernate over winter - the site of the Bees, Ants and Wasps Recording Society gives a record of a queen discovered beneath a rotting branch of cherry wood. She emerges around May and begins the process of constructing a nest and egg laying. By mid summer the nest is in full swing and may contain in excess of 500 individuals. Nests of one species of hornet (Vespa wilemani) have been recorded at altitudes of 2300m (Martin, Jpn.J.Ent.61(4), 679-682,1993). Come winter the nest is permanently abandoned (hornets do not reuse a nest the next year).

Figure 2 (click to further enlarge - if you dare!) shows a close up of my hornet's feasome jaws and, atop the head, the circle of small primitive light sentive 'eyes' (ocelli). Counting the number of segments on the antennae (=12) tells me my hornet is a female (males have 13)

A debate amongst professional naturalists concerns the mechanism and role of 'brood policing' in Vespa crabo. In brief the debate surrounds the question of why only the eggs of the queen, and not of the workers, are allowed to hatch (I was surprised to learn that the workers are not in fact sterile, and are quite capable of producing progeny). In the 60's the British evolutionary theorist W.Hamilton, argued mathematically that, other things being equal, in order to benefit their gene-line organisms ought to behave in ways that favour their close relatives (kin). Genetically however, a Vespa crabo worker is closer to its own offspring or indeed the offspring of a fellow worker than that of the queen. Despite this, workers ruthlessly seek out the eggs of fellow workers and discard them. Foster et.al. argue (Molecular Ecology (2000) 9, 735-742) that this may be due to the queen chemically controlling the 'minds' of the workers, hence the title of their paper 'Do hornets have zombie workers?' - although overall the jury seems still out.

Or at least that's my loose understanding of things. As I say often, I'm not a professional. I'm happy to be corrected and in particular I've not managed to follow the quantitative aspects of this debate. For example, Foster et. al. begin:

"In a colony headed by a singly mated queen, workers should prefer rearing sons (r= 0.5) and other workers’ sons (r= 0.375) to their mother’s sons(r= 0.25)'

I get the general idea, but can anyone give me a simple explanation of what these numbers mean and how they're calculated?

A lichen Caloplaca citrina

I am an amateur naturalist trying to discover everything living in my garden.

I've previously blogged the yellow lichen Xanthoria parietina that grows on the upper, east-facing exterior window sills of my house. On the lower sills there's another yellow algal/fungal partnership taking place (photo 1 - click to enlarge), this time in the form of a crustose, Caloplaca lichen.

I'm not a lichen expert, but having referred to the text books, I'm fairly confident the species here is Caloplaca citrina. The apothecia (the little, yellow spore-producing 'pin cushions') are spread about over a powdery, yellow thallus. Were this C. holocarpa (another common Calopaca with yellow/orange apothecia) the thallus would be grey. The thallus of C. dalmatia is cracked by thin black lines. The lack of any change in lichen texture / colour near the perimeter of the patch also distinguishes it from other various other superficially similar Caloplaca species such as C. decipiens. Identifying lichen is all about noting the tiny details!

There is yet another common possibility: the superficially similar powdery, yellow lichen Candelariella vitellina. In this case however there is an acid test (if you'll forgive the (chemically imprecise!) pun) to tell the two apart: a tiny drop of potassium hydroxide applied to most Caloplacas will turn them red. Candelariellas on the other hand, show no reaction. Photo 2 shows the positive result in my case.

I've read a suggestion that the purpose of yellow colouration in lichens is to provide protection against the harmful UV part of sunlight. I'm happy to accept this but it makes me wonder why only some lichens need to bother (there are plenty that don't: green, grey, white and even black lichens being commonplace - the two Verrucaria lichens I've previously blogged for example) .

Finally, the fact that C. citrina occupies the lower sills or my house and X. parietina the upper ones, makes me wonder whether the latter is more tolerant of low light conditions. Can anyone tell me?

Coal Tit Parus ater

I am an amateur naturalist trying to teach myself something about everything alive in my garden.

Taken on the same morning as my Blue Tit photo, photo 1 shows a Coal Tit (Parus ater) on my garden birdfeeder.

Averaging around 9-gm, Coal tits are the smallest British tit and easily recognised by their black crown and the white patch at the back of their head: No other British tit has the same. They are common in the UK, often inhabiting conifer woodland, the RSPB website giving the number of breeding pairs as 653,000.

What other I know about coal tits I've learned from reading The Titmice of the British Isles (John A.G.Barnes, publ. David&Charles 1975), this includes the rather charming fact that once mated a male-female pair will tend to remain bonded across the years, assuming both manage to survive that is; Annual mortality for coal tits is around 80%.

I was surprised to learn that coal tits make their nests very near to ground level in tree stumps or even in holes in the ground. I've spent many hours walking through woodland and don't recall ever having seen one, which I suppose must mean they're well concealed. Females lay on average 9 eggs around April-May. Coal tits are diligent parents and have been recorded making upwards of 60 visits to the nest in a single day to feed their chicks.

Coal tits spend a great deal of their day - around 90% - feeding. Given their small body size and slender beaks they consume the smallest insects (typically 0-2mm according to the book above) among the tits, an example of evolution driving different species to specialise in different feeding habitats and foodstuffs to best survive in one another's company. An exception to the rule is beech mast, which is so plentiful in Autumn that many different tit species come together to enjoy the glut.

Something I didn't know is that coal tits will sometimes store food (seeds etc.) for later consumption. Typical hiding places might be holes or under moss on tree trucks. There is a record of one bird digging up a seed that it had hidden more than a fortnight previously.

Finally, I have often wondered about the time at which birds go to bed. Of course 'late in the day', but is that as light is dimming, or say, a little after sunset? Dr. Barnes' book has answered my question: the coal tit is on average an early rooster, typically abed 1.7 minutes before local sunset. Good night!

Blue Tit Parus caeruleus

I am an amateur naturalist trying to learn something about everything living in my garden.

Some of you may recall that in my posting on White Tipped Bristle Moss I mentioned being impressed at the performance of the camera I was fortunate enough to borrow on that occasion. Well, I'm pleased to announce that the birthday fairies have since visited and I am now the proud owner of a fancy digital SLR. I offer this in explanation for why I have spent the greater part of Saturday morning, crouched in a 'birdhide' (a.k.a my garden shed!) my zoom lens trained on my garden birdfeeder.

Blue Tits (Parus caeruleus) are small birds (around 11gm, 11cm), easily recognised by the yellow breast, black eye stripe on a white face, blue crown, and blue and green dorsal (=viewed from back) feathers (photo 2 - click to enlarge). With experience (which I don't have!) it's apparently possible to distinguish males from females by the slightly smaller size and less vivid colourings of the latter.

The Blue Tit's call is a high pitched 'tsee-tsee-tsee' or occasionally a scolding 'churr'. They are one of Britain's commenest birds: The RSPB website gives the number of breeding pairs in the UK as approximately 3.5million.

According to my copy of The Blue Tit (Jim Flegg, Shire Natural History) female Blue Tits normally lay a single batch of between 5- and 16-eggs, during March or April. As with Robins, life is hard, and annual mortality in Blue Tits is around 90%. I had not hitherto realised that predators of the chicks include the Greater Spotted Woodpecker. Late summer and autumn see the highest mortality rates. More happily for my blue tit, birds that make it into Winter have a decent chance of reaching the Spring.

During Spring male Blue Tits defend terretories. During Autumn these break down and Blue Tits join large flocks of small birds roaming the hedgerows. During Winter a sort of 'half way house' emerges with birds forming smaller flocks and confining their travels to smaller (300-400m^2) areas. Again, like Robins, UK Blue Tits tend not to travel any great distance during their lives, <1% moving more than 100km although every few decades climate conditions lead to mass influxes ('irruptions') of birds from the European mainland.

A puzzle about Blue Tits, described in the book above, relates to their dietary fondness for Winter Moth (Operohtera brumata) and Tortix caterpillers. In some years in Oak woodlands, these attain epidemic proportions. Blue Tits seem able to predict (or to state things less anthopromorphically - there is a correlation between) when, and how many eggs to lay to take best advantage of the arrival of the caterpillers. How they do this isn't known, or at least wasn't when the book was written.

Finally, a fact well know to Brit's of a certain generation, which I include here for the interest of overseas readers, was the tradition (now rendered largely extinct by the ubiquitous supermarket) of having milk delivered to the doorstep in glass bottles capped with aluminium foil. It was to a national hazard to find Blue Tits had pecked through the foil to get at the cream below. You can find a photo of this here. Charming at first, but the householder soon learnt to leave empty youghurt pots out for the milkman to place over the bottles to thwart the theives!