I studied microbiology in college many years ago and one of the tests we had to conduct was on the toxicity of compounds in food. In the sciku above, I’m drawing a comparison with the toxicity we seek to isolate in biology and that we wish to isolate and avoid in our everyday lives.
Ancient crimson flame burning on lofty Olympus a new era is calling
by Sarah Das Gupta
Botanical name:
Amaranthus
Popular names:
Prostrate pigweed, Love lies bleeding
Family:
Amaranthaceae
Origin:
Central and South America. Currently found on all continents except Antarctica
Flower:
Catkin-like cymes, closely packed
Habitat:
Dry conditions, drought resistant
There are over 70 species of this ancient plant and they are very diverse. In 1996 Mosyakin and Robertson divided the family into 3 subgenres. There is some argument as to where and when the first plants were cultivated. It may be that both in South America and separately in south-east Asia cultivation occurred over 8,000 years ago.
In Ancient Greece the plant had spiritual significance. Its name means ‘unfading flower’, perhaps because it has a long flowering period. It was associated with immortality and believed to grow on Mount Olympus, the home of the gods. Aesop’s Fables also refer to the flower.
The Aztecs in the 15th and 16th centuries, grew three crops, beans, maize and amaranth. In a sacrifice to the god of war, the amaranth grain and honey were used to mould the image of the god which was later broken into pieces and eaten by the people. After the Spanish conquest, the cultivation of amaranth was discouraged as it was associated with old customs and religious practices.
Fifteen of the species have edible parts: the grain from the seed-head, the root and the leaves are high in nutrients and oxalates but some of the former are lost in cooking. However, with rises in temperature and growing interest in vegetarian diets, there may well be a future for this ancient plant. The seed-head produces a high yield while the plant is very drought resistant. In parts of Asia, amaranth is largely grown for its dye and for ornamental reasons.
Sarah Das Gupta is a young 81 year old. Loves writing haiku and most forms of poetry. Is learning to walk after an accident. Main outside interests include equine sports. Lives near Cambridge, UK. Read other sciku by Sarah here.
When it comes to food, a devil may indeed care. Picky scavengers.
Scavengers are opportunists, feeding whenever and on whatever they can. If an animal relies primarily on scavenging (instead of hunting) then food is not guaranteed and so it’s important to feed when they can. As a result, scavengers shouldn’t be picky eaters.
Yet recent research by Lewis et al. (2022) suggests that the Tasmanian devil may buck these expectations. The researchers took whisker samples from devils caught around Tasmania and analysed the stable isotopes present in them to determine what the devils had been eating.
Rather than seeing the generalised diet typical of a scavenger, the researchers found that most Tasmanian devils are actually dietary specialists, preferring to feed on specific foods (for example birds, wallabies or possums). Curiously, heavier devils were more likely to show this specialisation in feeding behaviour, although the reasons for this are as yet unknown.
So why are Tasmanian devils different from all other scavengers?
It may be because there are no larger predators to compete with in Tasmania – their main competition is each other. Medium-sized mammals, such as wallabies and possum, are common victims of road collisions which may mean that there’s an abundance of carcasses of these species for devils to choose from, which combined with reduced competition enables dietary specialisation.
Caring mothers aren’t the first thing that spring to mind when you think about spiders. Yet plenty of evidence exists of female spiders providing food for their young and protecting their offspring. A recent and very surprising example of arachnid maternal care comes from a species of ant-mimicking jumping spider.
Chen et al (2018) observed female spiders secreting a nutritious milk-like substance, which the offspring first consume from the floor of the nest and once they are a bit older directly from the mother herself. Through a careful set of experiments the researchers found that the spiderlings are entirely dependent on this ‘milk’ for survival, and that there are still huge survival benefits to it even once they are old enough to forage independently.
Milk provision was once seen as an exclusively mammalian trait but this research adds to growing evidence that the practice is more widespread across animal taxa than previously thought.
Dietary changes can lead to big health benefits, but there are global benefits to a change in diet too. Vanham et al (2018) have found that a healthy diet results in a decrease in the water footprint required to produce the food. Whilst healthy vegetarian or pescetarian diets have the lowest water footprint, even a change to a healthy diet containing meat results in a decrease in water footprint of between 11% and 35%.
Polar bears rely on marine mammals such as seals which are high-fat prey. Despite the richness of their diet however, new research suggests that a reduction in the prey availability can have severe consequences on polar bear survival.
Pagano et al (2018) monitored nine free-ranging female polar bears over 2 years, measuring their metabolic rates, daily activity patterns, body condition and foraging success. They found that more than half of the bears had an energy deficit resulting from a high metabolic rate (1.6 times higher than previously assumed) and a low intake of the high-fat prey. As fragmentation of sea ice continues and seals become harder to catch the high metabolic requirements of polar bears is likely to become increasingly catastrophic for the species.
Invertebrates are often used as live food for other animals in captivity (for example geckos are often fed live crickets). Increasingly there are suggestions that some invertebrate species may be able to experience a sensation of pain and may have higher cognitive functions such as emotions and learning. As a result, should we be considering the ethical and welfare issues associated with using invertebrates as live prey?
Keller (2017) has published a review of the latest research into invertebrates and how institutes using live prey might consider and act on any welfare implications. Since there is mounting evidence that some invertebrate species can suffer, perhaps it would be best to stop all live prey feeding? But this response has its own problems: live prey feeding provides enrichment to captive species and many captive species will not feed if the food item is dead.
Gut microbes are important for digestion, nutrition and immunity, and gut microflora may impact on life expectancy. Young African turquoise killifish have diverse microbial communities but this diversity decreases over time. By feeding middle-aged killifish the microbes from younger fish, Smith et al (2017) found that the older fish lived longer and were more active in later life. Manipulating gut microbe composition may therefore be a way of delaying diseases related to ageing.
Choosing what and how much to eat is crucial as even those nutrients that are normally beneficial can be harmful if consumed excessively. But the mechanism for how animals regulate the amount they eat isn’t always clear.
The common fruit fly develops a strong appetite for amino acid-rich food if fed a diet lacking in certain essential amino acids, and the fly’s reproductive effort will also decrease. However, this change in appetite and reproduction is suppressed if the fly has certain species of gut bacteria. Interestingly, when given the choice fruit flies will eat more food that contains these bacteria than food that doesn’t suggesting an ability of the flies to direct their own gut bacterial microbiome.
How the bacteria influence fruit fly behaviour and physiology is uncertain but results suggest that it is not down to the bacteria producing the missing amino acids for the flies or that the flies are consuming the bacteria themselves. Possible explanations are that the bacteria secrete metabolites that help the flies use their remaining amino acids more effectively or that the bacteria directly modulate the flies own nutrient sensing pathways so that the flies don’t recognise a decrease in amino acids. Leitão-Gonçalves et al, 2017.