BBC Wildlife - UK (2020-08)

Clockwise from bottom left: Getty; Laurent Geslin/NPL; MYN /Gil Wizen/NPL; Alan Murphy/NPL (x2); Solvin Zankl/NPL; Nigel Cattlin/FLPA

C

hildren often question if you’ll get

two worms by chopping one in

half. It’s true that an earthworm’s brain

and other vital organs are all at the head

end, so if it is cut in two behind the

swollen ‘saddle’ region, the front half of

the worm may regenerate a tail. But the

rear half will die.

More primitive flatworms (below) have

simpler anatomies, however. Splitting

in two is how some of these species

reproduce, and therefore dividing them

can result in a pair of clones. Tiny

marine flatworms are reportedly able

to recover from strategically placed

partial cuts, producing a two-headed (or

two-tailed) worm. A Harvard University

study of the snazzily named three-

banded panther worm revealed last year

that it can regenerate within eight days

of being sliced into thirds, in a process

termed ‘whole body

regeneration’.

Ellen Husain

Do worms survive

being cut in half?

INVERTEBRATES

MARINE BIOLOGY

ENVIRONMENT

I

n days gone by, the word

‘fish’ was pinned to

virtually any creature that

lurked beneath the waterline.

Gradually, as people paid more

attention to the biology of those

animals, it became clear that

some ‘fish’ belonged to other

groups, such as reptiles

or mammals. This left a

motley collection of aquatic

vertebrates, including

sharks, stingrays, hagfish,

sturgeon, lungfish, goldfish and

tuna. They are all animals that

(usually) breathe through gills,

have bodies covered in scales

(though not always) and limbs

in the form of fins.

The problem is that birds,

frogs, lizards, turtles, mammals

and all the other vertebrates

evolved from fish ancestors. So,

strictly speaking, those land-

dwelling vertebrates should all

be called fish, too. Generally,

though, most ichthyologists are

content to refer to the closely

related gathering of aquatic

animals as fish – as long as we

don’t go forgetting our own

fishy ancestry. Helen Scales

T

he marine environment has enjoyed

corona-quiet oceans, as COVID-19

brought the human world to a standstill.

A reduction in shipping and boat traffic

is making for quieter seas while less

road traffic is benefitting the terrestrial

environment, too. It’s as if the noisy

neighbours from hell have decided to

give it a rest and the animal kingdom is

enjoying the relative peace and quiet.

Recent research, published just

months before the coronavirus outbreak,

found that the impact of noise pollution

echoes through all animal phyla. From

amphibians, birds, fish and mammals

to reptiles, arthropods and molluscs,

there is very little variation between

these different animal groups in their

sensitivity to anthropogenic (human-

made) sound. Rather than viewing

noise pollution as a problem for the

hypersensitive few – such as bats and

whales – we should see it as a challenge

for the majority of species. Gillian Burke

Is there really no

such thing as a sh?

Which animals suer noise pollution?

Whatever you want to

class it as, the great

white shark is an

impressive creature.

Changing their tune: male

grasshoppers adjust the

pitch of their song so

females can hear them

above the urban din.

Q&A

82 BBC Wildlife August 2020