Sunday, 29 May 2016

Lichens and mosses

A leafy foliose lichen on the trunk of my Acacia karroo tree

After heavy rains we had in early April, many of my trees, and rocks, sported lichens and mosses, totally fascinating! And now, two months later, they are still there, but have turned pale grey. But understanding lichens is complex (to me at least!), so I've had to resort to an internet search to explain them.

Worldwide, over 20,000 species are known. A lichen is not a single organism. Rather, it is a symbiosis between different organisms - a fungus and an alga or cyanobacterium. Cyanobacteria are sometimes still referred to as 'blue-green algae', though they are quite distinct from the algae. The non-fungal partner contains chlorophyll and is called the photobiont. The fungal partner may be referred to as the mycobiont. While most lichen partnerships consist of one mycobiont and one photobiont, that's not universal for there are lichens with more than one photobiont partner. When looked at microscopically, the fungal partner is seen to be composed of filamentous cells and each such filament is called a hypha. These hyphae grow by extension and may branch but keep a constant diameter. Amongst the photobionts there are those that are also filamentous in structure while others are composed of chains or clusters of more-or-less globose cells.

Given that they contain chlorophyll, algae and cyanobacteria can manufacture carbohydrates with the help of light via the process of photosynthesis. By contrast, fungi do not make their own carbohydrates. Every fungus needs existing organic matter from which to obtain carbon. In a lichen some of the carbohydrate produced by the photobiont is of course used by the photobiont but some is 'harvested' by the mycobiont.

Lichens are classified with the fungi (being sometimes referred to as lichenized fungi) and can be found growing in almost all parts of the terrestrial world, from the ice-free polar areas to the tropics, from tropical rainforests to those desert areas free of mobile sand dunes.

Foliose lichens could be thought of as halfway between crustose (two dimensional) and fruticose (erect). Though obviously three dimensional, they grow in a more-or-less sheet-like form, but often with a lobed appearance. They are not attached by their entire lower surfaces to their substrates. Indeed, some foliose lichens are just centrally attached.

Another part of the same tree trunk, lower down, was covered in moss. Now Wikipedia says, "Mosses are small flowerless plants that typically grow in dense green clumps or mats, often in damp or shady locations. The individual plants are usually composed of simple, one-cell thick leaves, attached to a stem that may be branched or un-branched and has only a limited role in conducting water and nutrients."

The same thick mat of moss also formed on a rock on my patio, but both of them never quite got to the thick stage and have now all but disappeared. The moss life-cycle starts with a haploid spore that germinates to produce a protonema (pl. protonemata), which is either a mass of thread-like filaments or thalloid (flat and thallus-like). Massed moss protonemata typically look like a thin green felt, and may grow on damp soil, tree bark, rocks, concrete, or almost any other reasonably stable surface. This is a transitory stage in the life of a moss, but from the protonema grows the gametophore ("gamete-bearer") that is structurally differentiated into stems and leaves. A single mat of protonemata may develop several gametophore shoots, resulting in a clump of moss. But they do need a lot of damp to continue surviving.

Most mosses rely on the wind to disperse the spores, but It has recently been found that microarthropods, such as springtails and mites, can effect moss fertilization.

It seems that, given enough moisture, moss might still take over the world! lol!

Monday, 9 May 2016

Black-headed Heron (Ardea melanocephala)

I had an awesome visitor this morning, a Black-headed Heron (Ardea melanocephala). We don't often see them, mostly just after a veld fire, when they will snack on some unfortunate crispy tit-bits left in the wake of the fire. But this morning he was close to my garden fence and, as previously, didn't seem that perturbed about me taking some photos.

They mostly hunt near water, but will also hunt well away from water, taking large insects, small mammals, and birds. It will wait motionless for its prey, or slowly stalk its victim. It's fascinating to watch, but his patience long outlives mine, as he can stand motionless for longer than 10 minutes and by that time I think he's fallen asleep! Both sexes are alike, so I have no idea whether this is a male or a female.

Monogamous and usually colonial, they breed in small, mixed-species heronries. The male calls from a perch to attract a mate, raising its head and giving a loud yelp, sometimes extending its bill vertically as it does so. I've only heard that sound once, and I was totally thrilled!

Sunday, 24 April 2016

African Striped Skink (Trachylepsis striata)

This Striped Skink was enjoying the sun on the wall of my bathroom court-yard garden and she was heavily pregnant (pic taken last October). Mating occurs between October and November, with a gestation period are 90 to 100 days, so I presume she was to give birth within a month or two, usually a single litter of 3 – 9 babies. Growth is relatively fast, sexual maturity is reached in 15 – 18 months. Last summer, my Skinks had several litters in my bathroom court-yard garden, much to my delight.

The African Striped Skink (Trachylepsis striata), commonly called the Striped Skink, is a lizard in the skink family (Scincidae). The species is widespread in Southern Africa, including extreme southern Angola and Zambia, Namibia, Botswana, Zimbabwe, Mozambique, and parts of central and eastern South Africa.

Skinks typically seek out sheltered environments out of the elements, such as thick foliage, underneath man-made structures, and ground-level buildings such as garages and first-floor apartments. When two or more skinks are seen in a small area, it is typical to find a nest nearby. Skinks are considered to be territorial and often are seen standing in front of or "guarding" their nest area.

Two males squaring it off, ready to defend their territory

This skink is brown or bronze coloured with two yellowish stripes that run lengthwise on either side of the spine. Both sexes grow to a length of 25 cm.1 Their tails are often missing due to predators.

Monday, 18 April 2016

To bless this kind earth... and yourself

Now that we're over the worst of summer (and it really was the pits, with extreme heat-waves, temps in the 40℃'s and drought) and had some lovely rain to break the heat and drought, I'm enjoying time outside in my garden again. I just get absolutely cranky, and listless, when it gets that hot, and can't seem to get around to doing anything outside. But as we all know, we NEED to get outside, we need to spend time in nature, otherwise life becomes unbearable. Well, for me anyway. My plants and the birds in my garden are part of my family, and I feel as though I've lost track of what's going on in their lives. I just did the bare necessities during that heat, filling the water bowls and feed tables and the rest, like watering the garden, was left up to my trusty garden manger, Chrissie. I even thought of telling her to chat to the birds, because I wasn't getting round to it!

But my garden doesn't seem to have minded my absence. It's like a jungle out there after all the rain. Nature's revenge to neglect is that, when left undisturbed and given time, she will reclaim anything built by humanity. So basically, no need to feel guilty here, life finds a way.

 There's a pathway somewhere in there, totally covered now by Bulbine and Sword ferns.

Even the birds don't seem to have noticed my absence. No excitement or fluttering or welcoming twittering when I started spending time in the garden again. Maybe they were even pleased about not being constantly stalked by my camera. Eating and bathing and nesting carried on as usual, making me feel a bit unwanted...


Sunday, 14 February 2016

Hedgehog lore and legends - Snakes alive!

Are hedgehogs in danger from snakes?

It's not surprising that such a strange-looking little animal as a hedgehog should be the subject of some extraordinary legends and beliefs. Strange hedgehog activities such as running in circles and 'self-anointing' (smearing their spines with their own frothy saliva), are definitely fact, not fiction, through we don't know why they do these things.

But there are also a number of intriguing legends about hedgehogs, most of them dating back to the distant past.

The myth, particularly prevalent in South Africa, that snakes have been found with hedgehogs in their stomaches, is a long stretch of the imagination. It would be quite impossible for a snake, no matter how big, to swallow a rolled-up hedgehog.

A hedgehog under attack from a snake would immediate roll up and protect itself with its bristling spines. If the snake persists, it is likely to damage itself severely on the spines, and the hedgehog may seize the opportunity to sink its teeth into the snake and roll up again. In the end, the hedgehog often makes a meal of its former enemy!


Wednesday, 10 February 2016

Have we evolved for the better?

The animal kingdom is filled with almost an infinite variety of creatures. Scientists discover new species and sub species every year. Each one is a wonder onto itself and one could labour for years to uncover its secrets. It is an unfortunate fact that the closest that most of us get to wildlife is through bars at the zoo. Our urban lifestyle has the effect of cutting us off from the glorious world of the animal kingdom.

Every animal has a lesson to teach us that we are not hearing. We may think that we have evolved, the question is, at what cost?

A Butterfly Life
As the caterpillar sleeps inside its cocoon

Like a baby wrapped in her blanket 

She waits and waits until she blooms 
Into a beautiful new life 

With wings of deep sapphire blue

She takes her first flight, soaring high
Into the clear cornflower sky

She flutters over to perch on the pink flowers 

To sip the sweet nectar of pure gold 

But this butterfly is daintier than a ballerina

Like a leaf in the wind, but controlled

So delicate and fragile

But so free, so free this butterfly will always be.



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