Wednesday, 4 March 2015

Bird's-claw Beard-moss

Bird's-claw Beard-moss - Barbula unguiculata

Almost everyone can look at a tree and know that the green spongy covering is most likely a species of moss. Which species is the difficult question.
I definitely did not know that the moss I was photographing was called Bird's-claw Beard-moss, even though now I know it is one of the most common species found across Britain. It grows, just like most other mosses, in dense aggregations forming a mat like appearance in usually damp areas.

Mosses fall under the division Bryophyta which includes liverworts, hornworts and lichen. All these are small plants which do not have a vascular system and so stay quite small.Their similarities can easily lead to identification confusion which is furthered by confusing names such as 'Reindeer moss' which is in actual fact a species of lichen. They do not produce flowers and reproduce instead through spore formation. The gametophytes of moss are motile and rely on the moist environment to 'swim' to each other.

Mosses are abundant throughout the UK and can be found on structures such as buildings and paths which remain damp. It is safe to drink the water squeezed out of mosses, and in fact to eat most moss and lichen species. Having not eaten any moss here yet myself I cannot comment on their taste with confidence, though I have read they can be acidic and earthy. I quite like the earthy taste found in foods or smelt after a heavy rain - this is caused by a protein called Geosmin that is produced by Streptomyces a genus of Actinobacteria - if you do too, you might enjoy a nibble of moss!

Monday, 2 March 2015

Dunnocks Don't Date

Dunnock - Prunella modularis 

Dunnocks are a species of bird where the females are polyandrous. This means they mate with multiple males during one breeding season. The level of paternal uncertainty increases as males are unsure of how many other males the females has already mated with. From this the term sperm competition arises. Male dunnocks will peck at a females cloaca, urging her to eject the sperm from a previous male before mating.

Because of this method of competition between the males they invest little in extravagant plumage and so look very similar to the females.

A great video that explains this reproductive strategy can be found following the link below:

http://bbc.in/1DNwT3M

Despite this strategy being rather uncommon it can even be found in certain human groups. Females ensure resources from different males to her offspring by copulating with multiple males as each male knows there is a chance the offspring could be his own. This seems like quite an effective strategy but only if there is no way of the male finding out exactly which are his offspring. It relies on good female deceit, in the 'selfish gene' terms.

(The Selfish Gene by Richard Dawkins is a great book - read it!)