This has been – is being – a rough week, so this post is designed to be undemanding and easy on the eye. Continuing with the theme of patterns in nature, this week I feature spots and dots, shapes from nature that are appreciated and celebrated. Such patterns are re-presented in many forms, such as in leopard skin prints and polka-dot fabrics, but here I stick with dots I spotted in their natural form.
Spotted cats are perhaps the most famous representatives of dot patterns in nature. The cheetah (Acinonyx jubatus) in the photo above is a beautiful example.
Here is another photo of the same cheetah when he came out into more open ground near the road (photographed at Mabuasehube Game Reserve, part of the Kgalagadi Transfrontier Park in Botswana). Just look at those long and strong hind legs that can power him into incredibly fast action when he needs to give chase.
It is thought that spots help break up the shape of an animal and provide a form of camouflage, which can benefit predators such as cats, and also prey – think for example of spots dappling the fur of baby deer fawns. As they grow older they shed their spots as they moult into their adult coloration.
We don’t have deer occurring naturally in South Africa, only antelope, such as bushbuck (Tragelaphus sylvaticus). Bushbucks vary a lot in their colour and also in the number of stripes and spots that they carry, with some variations being characteristic of specific regional populations. The bushbuck in the photo above has only a few spots on its flanks, and no vertical stripes. I photographed this bushbuck as he crossed a road while I was walking near the campsite at Cape Vidal near St Lucia in the iSimangaliso Wetland Park World Heritage Site in KwaZulu-Natal.
Leopards (Panthera pardus) must surely be the king of spotted cats. We almost failed to notice this leopard sitting in dense vegetation not far from the road in Mabuasehube Game Reserve. I took this photo from the car window before the leopard moved off and it silently and swiftly melted into the foliage.
Taking its common name from the big spotted cat, this leopard magpie moth (Zerenopsis lepida) is striking in both its colour and spottedness. It was resting at dusk earlier this week on a potted pelargonium on our front deck.
Also named for the big spotted cat, this leopard lily (Ledebouria petiolata – previously known as Drimiopsis maculate) sports spots on its leaves. We can only speculate what practical purpose these spots might serve.
I can think of only a few plants with spotted leaves and they don’t occur in our garden. We used to have arum lilies (calla lilies – Zantedeschia aethiopica) with spotted leaves in the garden, but I have grown the next generation from seed and they have reverted to having leaves of a solid green colour.
The snake lily also known as the paintbrush lily (Scadoxus puniceus) bears spots at the base of young flower stalks in the spring.
Fern spores group into spot-shaped clusters on the underside of the leaf of a fern. For information on the complex life cycle of ferns and how they reproduce see here.
We do not have any obviously spotted flowers in our garden – so I stretched the pattern a bit to show the dots, dashes, splashes and stripes on the flowers of the ribbon bush (Hypoestes aristata).
There are small dots and three dark almost spot-like patches on the flowers of the yellow wild iris (Dietes bicolor) that grows in our garden.
It appears that more insects are likely to bear spots and dots than flowers. In the above photo, common-dotted fruit chafers (Cyrtothyrea marginalis) are feeding on nectar from the miniscule yellow male flowers on the spadix of an arum (calla) lily (Zantedeschia aethiopica). The female flowers are usually unseen as they are concealed where they form at the base of the spadix. The spadix is surrounded by a protective white spathe, which is commonly thought of as the flower of the arum.
Fruit chafers eat nectar and I have not found any eating the spathes of arum lily. I always leave the chafers to do their nectar-eating and pollinating thing with no apparent damage to the arums. In fact our arums produce a lot of seed – perhaps because of these visiting pollinators – and I collect the seed to generate new plants.
Ladybirds, or more accurately ladybeetles, are well known for their spots although not all species of ladybirds do in fact bear spots. Spotted or not their conspicuous colour serves as a warning to predators that they are toxic to eat. The only indigenous ladybirds I have photographed in our garden do not have spots, so we will have to make do with this spotted example, which unfortunately is an alien harlequin ladybird (Harmonia axyridis).
The brown commodore butterfly (Junonia natalica natalica) displays prominent spots some of which resemble eye-spots that may serve to deceive predators. The formation of patterns, including eye-spots, has been the subject of much scientific study.
Looking for an undemanding pattern to be the focus of this post, I thought spots might mean that mathematics would not come into the picture. I soon learnt that this assumption was wrong. In fact the formation of patterns and shapes in nature and their regulation, a process known as morphogenesis (literally the formation of a body’s shape), was the subject of a study by Alan Turing, who was a mathematician involved also in other academic disciplines and theoretical and practical fields of study. Perhaps he is best known for his code-breaking work at Bletchley Park in Britain during World War II and for his pioneering work as a computer scientist.
The small grass jewel butterfly (Freyeria trochylus – formerly Chilades trochylus) has an exquisite pattern that abounds with dots
Turing was also interested in mathematical biology, and in a 1952 paper “The Chemical Basis of Morphogenesis” he presents a mathematical model to explain the production and self-regulation of pattern morphogenesis in plants and animals.
The process of developing pattern formations involves two chemicals that react with each other as they diffuse through the body at a cellular level. These reaction-diffusion mechanisms Turing mapped mathematically. Only recently has computer modelling been able to demonstrate that Turing’s mathematical models can accurately predict pattern formation during development in certain species, for example in species of striped fish.
Well this very brief introduction is all I can manage for now, so I only add that further work is being done utilizing Turing’s models in investigating the development of patterning in animals, including in the hair of mammals and in feathers of bird – for more information see, for example, here.
The occurrence of spotted patterns in birds is relatively common, such as in the lovely spots on the plumage of an African olive (formerly Rameron) pigeon (Columba arquatrix), this bird photographed in our garden. Sometimes though the appearance of spots can result from how barring is revealed by overlapping feathers.
One of the best known of our spotted bird is the helmeted guineafowl (Numida meleagris). This one I photographed while it was resting on the grass at Kirstenbosch National Botanical Garden in Cape Town.
With a wig-like feathered ‘hairdo’, vivid scarlet eyes, and a kind of feathered jabot, the crested guineafowl (Guttera pucherani) also has spotted feathers on its body. I photographed the above crested guineafowl while we were walking at Kuleni Game Reserve, near Hluhluwe in KwaZulu-Natal.
The beautiful pattern formed by the markings on the feathers of a Burchell’s sandgrouse (Pterocles burchelli) is enlivened by white spots. A bird of the Kalahari Desert sands, this sandgrouse I photographed early one morning in the Central Kalahari Game Reserve in Botswana.
I find it somehow unexpected that the largest of our eagles, the African martial eagle (Polemaetus bellicosus), is decorated with spots. This eagle at Mkhuze Game Reserve in KwaZulu-Natal is ruffling its feathers and looking uncharacteristically frilly, in a photo that is somewhat grainy because it was taken at quite a distance.
And so I end this selection of spotted creatures and plants with a spotted hyena (Crocuta crocuta), a species that along with cats falls into the suborder Feliformia. I always find the intensity displayed by hyenas undeniable. This individual is making its way probably back to its den early one morning at the Addo Elephant National Park in the Eastern Cape.
The order Carnivora is divided into two suborders: Feliformia and Caniformia. Included in Felimormia, along with cats and hyenas are mongooses, genets, Malagasy carnivores, civets and Asiatic linsangs (I had to look them up). Included in the suborder Caniformia are dogs, bears, red panda, skunks, members of the Mustelidae family (ferrets, weasels, badgers, otters and so on), racoons, walruses and seals. I wonder how many species in these two suborders of Carnivora are spotted?
Sources: Chen, Jessica W. 2012. Understanding Pattern Formation during Morphogenesis. Harvard University. The Graduate School of Arts and Sciences. http://sitn.hms.harvard.edu/flash/2012/morphogenesis/; Untamed Science. [n.d.] Order Carnivora: The Carnivores. https://untamedscience.com/order/carnivora/
Posted by Carol