Q & A
Email your questions to wildquestions@immediate.co.uk
How loud are whales?
CHRIS VICK ANSWERS:
Very! Whales make all kinds of noises for a variety of reasons and there are some truly spectacular examples. The song of the humpback whale is not especially loud, but it can travel over hundreds or even thousands of kilometres.
The blue whale – the largest animal ever to have existed – has been recorded vocalising up to 188 decibels. To put that into perspective, a jet engine when a plane takes off emits about 140 decibels, and the threshold before humans experience pain is 120 decibels. Sperm whales can be even louder when they make sonic ‘clicks’ to explore the waters. Divers report ‘feeling’ the clicks and sonic booms reverberating through them.
Many whales rely on sound and the use of sonar to navigate their watery habitat. Yet the oceans are filling with human-made noise – oil and gas exploration, boats, military sonar and more. And whales may struggle to make themselves heard.
Why aren’t common gulls all that common?
DAVID LINDO ANSWERS:
This dainty gull is very similar looking to its larger cousin, the herring gull, and thus is often overlooked. And despite the name, it is actually one of the scarcest of our regular gulls. It is principally a winter visitor to most of the UK, with numbers augmented by many Scandinavian birds. They are partial to loafing on sports fields, landfill sites and the green spaces within housing estates. Their breeding populations in the UK are based predominately in northern England and Scotland.
The name ‘common gull’ was first coined by Welsh naturalist Thomas Pennant in 1768 because he thought that it was our most numerous gull. The accepted thinking now is that it is so named because it breeds on common land in parts of Scotland and winters on common land throughout the rest of Britain.
Why do flies rub their hands together?
ERICA MCALISTER ANSWERS:
Okay, first off – flies don’t actually have hands, instead they have something called tarsi (from the Greek tarsos, which roughly means ‘flat surface’). The tarsus is the segment on the leg that is furthest from the body and comprises several smaller segments, ending with one or two claws.
A fly’s tarsi are used for walking, grabbing, tasting and, importantly, cleaning. For although you may think that flies have some less-than-salubrious habits, to maintain all of their activities they must keep their sensory equipment clean. And so, with these often rather hirsute tarsi, they clean their heads – particularly their eyes – wiping away any particles that may have become stuck there.
Not only are they cleaning their heads, but by rubbing the tarsi they are also freshening-up the smell and taste receptors located on them. Tasting with your feet is incredibly useful in helping you determine whether something is edible without having to get your delicate mouthparts out.
Why do we react badly to onions and chillies?
DAVID HAMILTON ANSWERS:
Growing onions absorb sulphur from the soil. This is stored in cells in the form of amino acid sulfoxides. When the onion is cut, its cells release special enzymes along with these amino acids. These react together, forming sulphenic acid, which quickly converts into a catchily-named gas called syn-propanethial S-oxide. On contact with our eyes, this gas overstimulates basal tears as our eyes try to eliminate it.
Chillies also burn, but rather than forming an acid, they work in a slightly different way. The burning sensation we feel is thanks to a compound called capsaicin. When you chow down on a chilli, this capsaicin binds with pain receptors in the tongue that trick the brain into thinking the mouth is on fire. The body then does what it can to get rid of this perceived danger – causing our eyes to water and our skin to create sweat.
RECORD BREAKER!
What’s the world’s longest snake?
This accolade is awarded to the reticulated python, which can be found in the rainforests, grasslands, woodlands and occasionally even the sewers of South and South-East Asia. The longest ever recorded individual was found in 1912 and measured 10m, and the longest in captivity was a female in the USA that measured 7.67m. This non-venomous species is also amongst the three heaviest snakes. MS
FACT.
Nine-banded armadillos always give birth to quadruplets. After fertilisation of a female’s single egg by a male, the zygote implants in the uterus and splits into four identical embryos.
WHAT ON EARTH?
Sticky situation
The description of a fellow human as “no stick insect” is rarely meant as a compliment. Directed at a member of the Proscopioidea, though, it is just a statement of taxonomic reality. These twiggy characters look, move and eat like stick insects – in this case, one that looks as if it has just been caught raiding the fridge after midnight – but they belong to an entirely different group of insects. Stick grasshoppers, as they are less formally known, are found across tropical America and can be distinguished from their twiggy lookalikes by hind legs built for jumping, elongated faces and high-set eyes. SB
What is a false autumn?
ANDREW SMITH ANSWERS:
When and why the leaves of a tree change colour and drop depends on many different things as trees react to their environment and adapt to their growth.
When it’s hot and dry, a tree may be losing too much water and so drops some of its leaves. This is known as ‘summer leaf drop’. It can be mistaken as autumn but is in fact a ‘false autumn’ where typically only 20 per cent of a tree’s leaves are lost. This is a normal response and doesn’t usually affect the health of the tree – unless it happens for several years in a row.
Of course, tree species react in a range of ways and some are more tolerant of hot, dry weather. Even individuals of the same species planted in different conditions can react differently. Planting a variety of species using seed from separate provenances will ensure the resilience of our nation’s forests in a changing climate.
FAST ANSWERS
Why is the blobfish so ugly?
Droopy, gelatinous and with a large bulbous nose, the blobfish rose to fame when it was voted the ugliest fish in the world in a public poll. However, it’s worth noting that specimens of this fish species suffer from decompression damage when brought to the surface. At the extreme depths where it is naturally found, it actually looks like a normal fish – so perhaps we’ve all been judging it too harshly. MS
What are daddy long-legs?
It depends who you ask! Usually this refers to spider species in the Pholcidae family, particularly the cellar spider (pictured) – the species that hangs out on ceilings and vibrates dizzyingly fast if touched. However, the name ‘daddy long-legs’ is also sometimes used to refer to craneflies or harvestmen. MS
Are there any animals named after Pokémon?
We’ve previously covered the Pokémon creatures based on real-life animals (see discoverwildlife.com/pokemon), but did you know that it’s also happened in reverse? In 2016, an entomologist named a Chilean bee species after the draconic Charizard, calling it Chilicola charizard. MS
INSTANT EXPERT
The phenotype: nature via nurture
ANY OBSERVABLE CHARACTERISTIC or combination of traits – not just something like colour or behaviour, but features you can’t easily see, such as physiology – are known as an organism’s phenotype. These features are a product of genes and influenced by the environment – so a phenotype is the physical manifestation of genetic instructions.
What’s the genotype?
The genotype is the combination of genes that produces a particular phenotype. When an individual inherits one copy of a gene from its mother and one from its father, those two copies are either distinct genetic variants (alleles) or the same. Two variants will differ in their DNA sequence, but the distinction between them is traditionally represented by capital and lowercase versions of a letter.
A classic example comes from Gregor Mendel – a19th-century monk and father of genetics – who studied flower colour as part of his breeding experiments in pea plants. From a single gene with two variants, ‘A’ and ‘a’, a copy from each parent gives four possible genotypes: AA, Aa, aA, aa. By crossing two pure-bred parents – one with white flowers, the other purple – Mendel showed that offspring had purple flowers if they carried the dominant ‘A’ variant of a gene, but had to inherit both copies as the ‘a’ (recessive) variant to end-up with the white phenotype. That study inspired the concept of ‘dominance’, one of Mendel’s laws of inheritance.
So genotype determines phenotype?
Sometimes, but be wary of ‘genetic determinism’! That’s the belief that traits are caused by genetics alone. It’s important to note that many phenotypes aren’t simply ‘monogenic’ traits dictated by a single gene, as phenotypes can also be ‘polygenic’ traits that depend on multiple genes. Saying that genes determine traits is a convenient shorthand, and one genotype can actually produce a variety of different phenotypes.
Why might a phenotype not reflect its genotype?
Because the link between them can be influenced by environmental factors, such as a habitat’s resources or how an individual is raised. If you’re not careful, that idea can lead you to believe that traits are determined by either genes or the environment – nature or nurture, which is another common misconception.
Variation in phenotypes exist because genes aren’t isolated from other factors that cause ‘gene-by-environment’ interactions.
Think of twins with identical genotypes for the potential to grow muscle: only the one who lifts weights ends up with a muscular body. So a phenotype is the result of nature via nurture.
How do phenotypes affect evolution?
A genotype is often invisible to natural selection because variants are hidden behind environmental factors or a genetic phenomenon like dominance. That means ‘survival of the fittest’ actually occurs between individuals according to their visible phenotype. Because only survivors pass genes to the next generation, an organism’s genotype survives by being dragged along with its phenotype.
That effect explains why harmful genetic variants (‘bad mutations’) can persist in a population’s gene pool over time. For example, with sickle-cell anaemia, people who inherit two copies of a defective gene have abnormal haemoglobin and short-lived, crescent-shaped red blood cells. Carrying just one copy causes ‘sicklecell trait’, where a person will carry the abnormal variant (and may pass it on to their children), yet won’t suffer from disease. Although affected individuals are less likely to survive and reproduce, the variant survives in places where malaria is endemic because the parasite is less able to infect people with sickle-cell phenotypes.
What’s the ‘extended phenotype’?
It’s a concept proposed by Richard Dawkins, who argued that a gene’s effect can extend beyond the body to produce phenotypes in an organism’s surroundings. Humans are an obvious case, because we create structures such as buildings and roads, but in his book, The Extended Phenotype, Dawkins presented the example of a beaver’s dam – an artificial structure that the animal makes through planning and dexterity, which is ultimately determined by its genes.
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EYES AND VISION
How animals see the world
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