New Scientist - USA (2021-11-06)

6 November 2021 | New Scientist | 25

Zoology

HUMANS and seals look remarkably

similar in the water from a great

white shark’s perspective, adding

evidence to the idea that shark

bites on humans may be a case

of mistaken identity.

Although shark bites on humans

are extremely rare, they cause a

significant and disproportionate

amount of public concern.

Laura Ryan at Macquarie

University in Australia and her

colleagues made video recordings

of a seal and a sea lion swimming

in tanks, and also recorded people

swimming and paddling on a

surfboard in a tank.

To assess the visual similarity

from the perspective of juvenile

great whites, which are responsible

for the majority of shark bites, the

team analysed the recordings using

a model of the sharks’ visual system,

taking into account their colour

blindness and inability to see detail.

The researchers found that the

sharks would see little difference

between the motion of humans

swimming, humans paddling on

surfboards and seals and sea lions

swimming. They also found that

seals and sea lions with their fins

out looked similar in shape to

human swimmers and surfers

(Journal of the Royal Society

Interface, doi.org/g35z). Chen Ly

Why sharks may mistake

surfers for seals and sea lions

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Panda’s coat acts as

great camouflage

The distinctive black-and-

white coat of the giant

panda helps the bears hide.

When images of pandas in

forests were fed through a

program that simulates the

visual system of predatory

cats, the pandas were

difficult to spot, particularly

if they were tens of metres

away (Scientific Reports,

doi.org/g35r).

‘5D’ storage beats

Blu-ray technology

A method of writing

on glass could squeeze

500 terabytes onto a single

disc – 10,000 times more

data than fits on a Blu-ray

disc. Dubbed 5D storage,

it writes data using two

dimensions of laser

light – based on intensity

and polarisation – and

three spatial dimensions

(Optica, doi.org/g35s).

Unowned cats in UK

number 250,000

With the help of residents

in five UK towns, an

estimate has been put

on the number of lost,

abandoned and feral

cats living in UK urban

centres. Knowing there

are potentially 250,000 of

them will help authorities

monitor the population in

the years ahead (Scientific

Reports, doi.org/g35v).

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Ornithology

BIRDS have been found to eat

truffles – fungal fruiting bodies

that were assumed to be eaten

only by mammals. The discovery,

in the Patagonian region of South

America, suggests birds in this

area play an important role in

the dispersal of truffle spores.

Matthew Smith at the

University of Florida and his

colleagues collected 169 bird faecal

samples mainly belonging to two

bird species, the chucao tapaculo

(Scelorchilus rubecula) and the

black-throated huet-huet

(Pteroptochos tarnii). The

researchers collected the samples

in Patagonia in 2018 and 2019.

They then used DNA analysis

to identify truffle spores in the

samples, as well as fluorescence

microscopy to see whether the

spores were intact.

They found truffle spores in

42 per cent of chucao tapaculo and

30 per cent of black-throated huet-

huet samples. Many of the spores

in the faecal samples were intact,

which means they were still viable

(Current Biology, doi.org/g354).

The findings suggest that birds

play a large role in spreading

truffles to new areas throughout

the forests of Patagonia. They also

imply that fungi are a big part of

these birds’ diets. CL

Birds have a

taste for truffles

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Particle physics

THE hunt for mysterious

theoretical particles known

as sterile neutrinos has turned

up empty again.

Neutrinos are subatomic

particles that barely interact with

regular matter. There are three

known types and the search for

a fourth, called sterile neutrinos,

has been going on for decades.

These get their name because,

unlike the other three types, they

would only interact via gravity.

Because neutrinos are so small

and interact so weakly with other

matter, we can only observe them

indirectly, via the products of

collisions between other particles.

Two neutrino experiments have

previously found more of these

products than expected. However,

neither could tell the difference

between electrons and photons in

its results – and sterile neutrinos

would only produce extra

electrons. An experiment called

MicroBooNE at the Fermi National

Accelerator Laboratory in Illinois

can tell the difference, but its

first three years of data show

no extra neutrino products.

“I would have expected to see an

excess in either the photons or the

electrons and we haven’t seen one

in either, which opens up more

questions,” says MicroBooNE

spokesperson Justin Evans at the

University of Manchester, UK.

Is the hunt over? “We definitely

are not seeing any evidence for a

sterile neutrino,” says Evans. “As

to whether it is completely dead,

I think that depends who you ask,

but you’ve certainly got to get a

lot more inventive to get a sterile

neutrino into your particle physics

models now.” LC

Physicists fail to

find sterile neutrino