BBC_Science_Focus_-_08.2019

DISCOVERIES

ink or swim

Seals can consciously control their circulatory systems before diving

When submarine crews in movies hear
“Prepare to dive!”, they jump into action
to get the vessel ready to submerge. A new
study, led by Dr J Chris McKnight of the
University of St Andrews, suggests seals
use an equivalent thought to prompt the
physiological changes needed to help them
stay underwater for so long.
The team studied a group of harbour
seals (Phoca vitulina) wearing near-infrared
spectroscopy devices, which track patterns
of blood circulation. These PortaSeal
wearables were attached to the animals’
heads and shoulders to monitor changes in
their bodies while swimming and diving in
a quasi-natural foraging habitat.
“Discovering that seals can seemingly
actively exert control over their

ZOOLOGY

EKTEWNCVQT[ U[UVGOU KU TGCNN[ GZEKVKPIq

says McKnight.

Mammals, including humans, have a

range of automatic cardiovascular responses

to being submerged in water, including a

reduced heart rate and constriction of the

peripheral blood vessels in their limbs

and extremities – a process known as the

OCOOCNKCP FKXKPI TGGZ/CTKPG OCOOCNU

GZJKDKV VJKU TGGZ RCTVKEWNCTN[ UVTQPIN[DWV

we cannot see inside their bodies before

and during a dive to see the extent of

changes that they undergo.

McKnight and his team wondered if

near-infrared spectroscopy (NIRS), used

VQ OQPKVQT DNQQFQY CPF QZ[IGPCVKQP

levels in brains, might provide the answer.

It involves shining light (of wavelengths

between 800 and 2,500 nanometres)

into the subject’s head and analysing

VJG URGEVTWO QH NKIJV VJCV TGGEVU DCEM

Different molecular bonds absorb different

YCXGNGPIVJU QH NKIJVUQ VJG TGGEVGF

wavelengths provide clues as to the amount

of blood passing through vessels in the

subject’s brain and surrounding tissue.

The results showed that seals constrict

their peripheral blood vessels and

boosted their cerebral blood volume

about 15 seconds before diving. These

anticipatory adjustments suggest that

blood redistribution in seals is under some

EQIPKVKXG EQPVTQN CPF PQV UKORN[ C TGGZ

response to submersion. Seals also increase

oxygen in their brain at a consistent time in

each dive, despite a lack of air.

A tracking device weighing just

one-tenth of a gram and small

enough to be fixed to a bumble

bee’s back was made by a team

at the University of Washington.

A white beluga whale wearing a

harness with a GoPro camera

holder and label suggesting it

came from St Petersburg,

Russia, approached a fishing

boat in Norway. A defecting spy?

University of

Birmingham

researchers have

developed

sensor-packed

backpacks for pigeons to collect

data on urban microclimates.

BRAIN ENERGY LINK TO

CHILDHOOD OBESITY?

American researchers speculate that

childhood weight gain may be linked to the

amount of energy the brain uses. Research

has shown that, in five-year-olds, the brain

uses almost half of the body’s energy. This

has implications for weight gain, which, at

its simplest, occurs when someone’s energy

burn is less than their calorie intake.

ANIMAL

WEARABLES