Q & A
Email your questions to wildquestions@immediate.co.uk
Are all parts of a yew poisonous?
DAVE HAMILTON ANSWERS:
The yew tree (Taxus spp.), commonly found in churchyards and grand gardens, is one of the most poisonous woody plants in the world. Nearly all parts of the tree contain a toxic alkaloid called taxine. Taxine in small doses, typically under 50g of yew material, would be enough to cause severe gastric upset. However, doses over 50g or more (the equivalent weight of two AA batteries) would be enough to kill an adult human.
The tree’s toxicity may be one of the reasons it was planted in so many churchyards. Locals would have been put off taking their animals to graze in the churchyard for fear of poisoning. The seed of the tree is also highly toxic, yet the flesh surrounding the seed is edible and sweet tasting, but you would need to spit the seed out or remove it before you swallow – and we wouldn’t recommend it!
What is the largest moth?
STUART BLACKMAN ANSWERS:
The answer to this really depends on what you are measuring – surface of the wings, wingspan or weight. The title is most commonly bestowed upon two giant silk moths: the East Asian atlas moth and the Australasian Hercules moth, which can confidently be compared to dinner plates on the basis of the surface area of their wings.
However, if you were to measure by the wingspan, both of these are beaten by the white witch moth of tropical America – aBrazilian specimen was once recorded at very nearly 30cm across. Also known as the ghost moth (this common name is also used for a UK species), great grey witch and great owlet moth, it’s a mysterious species whose caterpillars have still not been found.
If weight is what you’re interested in, then Australia’s giant wood moth is the clear winner at 30g – about 50 per cent heavier than a robin. Its huge larvae, which bore into the trunks of eucalyptus trees and are in turn eaten traditionally by indigenous Australians, may well be the world’s biggest caterpillars, although that, too, will depend on what you are measuring.
FACT.
In the 1890s, a US society released 100 European starlings in Central Park as part of an attempt to introduce birds mentioned by Shakespeare.
Do bullfinches ever nest in gardens?
DAVID LINDO ANSWERS:
In former times, the bullfinch was a common bird in our British gardens. Unfortunately, they have declined considerably since then and these days their sporadic appearances can spark great delight. They are shy visitors but stunning to behold, with the male’s rich red underparts being particularly striking.
They nest from May to July within dense undergrowth, usually in woodlands, but also in hedgerows, parks and, yes, large gardens.
Bullfinches can nurture three broods a year and once the eggs hatch – normally within three weeks of being laid – both sexes help to feed the young.
Despite nesting in very secret areas, adults can travel long distances in search of food for their offspring, especially if their seed supplies are in short supply. They have specially developed food sacs positioned in the floor of their mouths for the parents to bring food back to their young. They are the only species of finch to have such an adaptation. Amazing!
Does the UK have any scorpions?
MEGAN SHERSBY ANSWERS:
The UK lacks any native scorpion species, but one non-native species has managed to make itself at home on the Isle of Sheppey in Kent – the European yellow-tailed scorpion. Measuring up to 45cm in length, this mostly black scorpion species (with yellow-brown legs and tail) is thought to have arrived in the 1800s in shipments of Italian masonry. The population is believed to be the northernmost population of wild scorpions outside of the Americas.
The UK does have 27 pseudoscorpion species, however. Much smaller than scorpions, and only measuring up to 8mm in length, these arachnids have two long pincers like scorpions, but lack the infamous stinging tail.
RECORD BREAKER!
What’s the world’s smallest cat?
The rusty-spotted cat and black-footed cat are both contenders for this title, measuring 35-48cm and 35-52cm in length respectively. Both species are thought to be nocturnal, feeding on rodents and small birds – though black-footed cats are known to prey on Cape hares, which are heavier than them. Whilst the black-footed cat is usually solitary, little is known about the behaviour of the rusty-spotted cat.MS
FACT.
The pygmy shrew has the fastest heartbeat of any mammal at 1,200 beats per minute. In comparison, an adult human’s resting heart rate is much lower, usually 60 to 100 beats per minute.
WHAT ON EARTH?
Zombie hunter
If spiders ate zombies, we might see more disembodied forearms of the un-dead decorating silken webs. They don’t, of course. What looks like a severed humanoid limb is the very spider that made the web. By day, this tree-stump orb-weaver sits motionless on a branch, where it convincingly passes for a snapped twig. Only with the arrival of darkness does it emerge from the safety of the undergrowth to spin its snare. And as daylight begins to break, it will dismantle its web and resume its twig-like pose on a nearby branch. SB
Why is rosebay willowherb known as ‘bombweed’?
DAVE HAMILTON ANSWERS:
As summer comes to a close, the tall pinkish-purple flower spikes of rosebay willowherb give way to a multitude of fluffy, wind-dispersed seeds. These seeds allow the plant to be one of the first colonisers of empty ground.
During World War II, this ability to seed disturbed and cleared land saw the plant thrive. By 1946, it had spread across bombsites all over London, gaining the name ‘bombweed’. It also goes by the names ‘fireweed’, from its natural tendency to grow on land cleared by fire, and ‘blooming Sally’, from a corruption of the word ‘Salix’, the scientific name for willow.
It’s an important wildlife plant, not only for pollinators, but also as a food source for the caterpillars of numerous moths. Elephant hawk-moths and the bedstraw hawk-moth are among those who enjoy snacking on the leaves. For us humans it can be useful too. In Russia, it is made into Ivan’s tea, a delicious caffeine-free alternative to black tea.
FAST ANSWERS
Why do beavers have orange teeth?
If you’ve ever caught a glance of a beaver’s teeth, you may have been shocked to see that they are orange in colour. This is because the protective coating of enamel is very rich in iron, in the form of ferrihydrite and ironcalcium phosphate. MS
Are sturgeon endangered?
Sturgeon and paddlefish have been swimming in our rivers and seas for about 250 million years and shared the planet with the dinosaurs. But they face an uncertain future. All 26 remaining species are threatened with extinction and collectively they are considered the most endangered group of animals on Earth. Conservation efforts focus on tackling overfishing, the illegal caviar trade and the harmful effects of dams and pollution.DT
What is vivipary?
A rather odd-looking phenomenon, sometimes seen in plants such as tomatoes, strawberries and teasels, vivipary is when the seeds start to develop and germinate whilst still attached to, or still within, the parent plant. MS
INSTANT EXPERT
Vision: more than meets the eye
ALMOST ALL ANIMALS HAVE EYES TO sense light in their environment – even in dark habitats such as the deep ocean, where the only source might come from the odd burst of bioluminescence. But although species across the animal kingdom have evolved various structures for sight, they all need special cells called photoreceptors.
What are photoreceptors?
They’re cells that transform light energy into electrical signals that can be interpreted by the brain. There are two types based on shape: rods and cones. Rod cells are built for contrast (black versus white) and contain the light-sensitive pigment rhodopsin. A cone cell will carry one of many pigments, each tuned to a specific range of wavelengths – matching a colour – on the visible spectrum.
The number and type of photoreceptors an animal has dictates which colours it can perceive. Humans have three kinds of cones or ‘spectral classes’ for trichromatic vision (around red, green and blue wavelengths). In comparison, butterflies and mantis shrimp have a dozen classes to cover a broader range of the spectrum (from deep ultraviolet to far-red light), which gives them hyperspectral vision.
But there’s more to sight than sensing light, right?
Very poetic! Yes, vision also requires neural circuits. The electrical signal generated by a photoreceptor is relayed via branching neurones that connect to other nerve cells, which amplify or dampen signals before they reach the brain. The brain then processes complex patterns in that visual information to detect the edges of objects and form an image of the outside world.
Speaking of circuitry, how’s this for ‘intelligent design’? In vertebrates like humans, light only hits photoreceptors after passing through the neural wiring. But in cephalopods, eyes are wired sensibly: behind light-sensitive cells.
Enough neuroscience. What about eyes?
Well, one reason they come in pairs is so animals can calculate distance. But like most features, sight is an adaptation to an ecological niche, leading to a trade-off. Prey typically have monocular vision – an eye on each side of their head so two fields of view can be combined into one large visual field, helping them watch out for hunters. But predators have binocular vision, with forward-facing eyes so fields can overlap for depth perception, helping them spot food.
Eyes have a layer of photoreceptors and neurones – the retina – spread across a curved surface so that the brain can compare light and shade on separate cells to deduce direction. Evolution has since elaborated on that basic plan to create a variety of eyes – 10 distinct forms, in fact, with two main kinds: simple and compound.
What’s a simple eye?
The organ is simple because it’s made up of a single chamber with a concave retina at the back of the eye. Some worms, larvae and molluscs have open ‘pit eyes’, but more complex creatures have a closed eyeball with a window (cornea) to help direct light beams to numerous photoreceptors on the retina. Many animals have a diaphragm (iris) that adjusts the amount of light entering the eye through its aperture (pupil).
To produce sharp images, scallops and certain crustaceans use mirrors, but the majority of species focus light using lenses. Fish and other aquatic organisms have a spherical lens, whereas land animals have a disc lens and the eye is filled with a gel or ‘vitreous fluid’ that refracts light as it travels from air into the fluid medium (like a ‘bent’ straw in a glass of water).
How does a compound eye differ?
It’s composed of multiple chambers, optical units called ommatidia, arranged in a convex structure. While each ommatidium only captures a blurry image, because it directs light at narrow angles to relatively few photoreceptors, the signals from each facet are pieced-together by the brain to from one pixelated image.
The multifaceted eyes of insects aren’t inferior, merely different. If a simple eye is like an HD television, a compound eye resembles the wall of screens in a CCTV control room: each individual screen doesn’t show much detail, but a change to one is noticeable and reveals sudden motion. This helps explain why a house fly can easily avoid being swatted by, say, a rolled-up copy of BBC Wildlife.
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