The New York Times - USA (2020-12-01)

The shrimp stop swimming at dusk and gather near

the river’s edge. After sunset, they begin to climb out

of the water. Then they march. All night long, the

inch-long crustaceans parade along the rocks.

The parading shrimp of northeastern Thailand

have inspired legends, dances and even a statue. (Lo-

cals also eat them.) During the rainy season, between

late August and early October, tourists crowd the riv-

erbanks with flashlights to watch the shrimp walk.

Watcharapong Hongjamrassilp first learned about

the parading shrimp, and the tourists who come to

see them, about 20 years ago. When he started

studying biology, he returned to the topic. “I realized

that we know nothing about this,” he said: What

species are they? Why and how do they leave the

safety of the water to walk upstream on dry land?

Where are they going?

Mr. Hongjamrassilp, a graduate student in Califor-

nia, decided to answer those questions himself. His

findings appeared in a new study released this

month. Working with wildlife center staff members,

Mr. Hongjamrassilp staked out nine sites along a

river in the Thai province of Ubon Ratchathani and

found shrimp parading at two of the sites — a stretch

of rapids, and a low dam.

Videos they recorded revealed that the shrimp pa-

raded from sundown to sunup. They traveled up to

65 feet upstream. Some individual shrimp stayed out

of the water for 10 minutes or more.

“I was so surprised,” Mr. Hongjamrassilp said, “be-

cause I never thought that a shrimp can walk that

long.” Staying in the river’s splash zone may help

them keep their gills wet, so they can keep taking in

oxygen. He also saw that the shells of the shrimp

seem to trap a little water around their gills, like a

reverse dive helmet. ELIZABETH PRESTON

CRUSTACEANS, ACTUALLY

When Shrimp Start Acting Like Fish Out of Water

WATCHARAPONG HONGJAMRASSILP

Observatory

FINDINGS, EVENTS AND MORE

D2 N THE NEW YORK TIMES, TUESDAY, DECEMBER 1, 2020

‘We are now on a landing course for Earth. The altitude will now gradually decrease towards Woomera.

Fasten your seatbelt firmly, and if you are traveling with young children, please assist them.’

Yuichi Tsuda,project manager of Japan’s Hayabusa2 spacecraft, which is scheduled to eject a canister full of samples collected from the asteroid Ryugu down to the Australian outback on Sunday.

When food gets scarce, monarch butterfly caterpil-

lars will turn on one another, duking it out for the

rights to grub, according to a new paper. The jousts

don’t get bloody, but they involve plenty of boxing

and body-checking.

The study focuses in on the phenomenon of

caterpillar aggression. It could also aid entomolo-

gists racing to preserve monarchs and the milk-

weed plants they depend on, as populations of the

species continue to plummet. “It’s interesting to

think about how this would potentially impact the

survival of these caterpillars, when they’re

crowded onto plants,” said D. André Green, a Mich-

igan biologist who wasn’t involved in the study.

“The amount of milkweed is decreasing.”

Alex Keene, a neuroscientist at Florida Atlantic

University and an author on the study, was first

inspired to tackle the project after he and his wife

noticed two monarch caterpillars tussling on a

milkweed plant in his backyard.

The altercation made a lasting impression on Dr.

Keene, who scoured the internet for scientific data

documenting these milkweed melees. There was

nothing. So he and his colleagues decided to fill the

gap themselves. KATHERINE J. WU

TUSSLING MONARCHS

It’s Not Wise to Get Between

A Caterpillar and Its Milkweed

FLORIDA ATLANTIC UNIVERSITY

Paleontologists call it the Permian-Triassic mass
extinction, but it has another name: the Great
Dying. It happened about 252 million years ago,
and, over the course of just tens of thousands of

years, 96 percent of all life in the oceans and, per-
haps, roughly 70 percent of all land life vanished.
The smoking gun was ancient volcanism in what
is today Siberia, where volcanoes disgorged
enough magma and lava over about a million years
to cover an amount of land equivalent to a third or
even half of the surface area of the United States.
(Above, a fossil of brachiopod shells that showed
clues of very high temperatures.)
But volcanism wasn’t the only factor. The Great

Dying was fueled, two studies say, by extensive oil
and coal deposits that the Siberian magma blazed
through, leading to combustion that released
greenhouse gases like carbon dioxide and meth-
ane. The findings show what a changing climate
can do to life on our planet. LUCAS JOEL

ANCIENT CLIMATE CHANGE

Burning Fossil Fuels Helped Drive

Earth’s Largest Mass Extinction

RENATO POSENATO/FERRARA UNIVERSITY

Daily nuggets of science for
mobile readers:
nytimes.com/trilobites

ONLINE:TRILOBITES

For a rodent resembling the love child of a skunk

and a steel wool brush, the African crested rat

carries itself with a surprising amount of swagger.

In sharp contrast to most of their skittish rodent

kin, Lophiomys imhausi lumber about with the

languidness of porcupines. When cornered, they

fluff up the fur along their backs into a tip-frosted

mohawk, revealing rows of black-and-white bands

that run like racing stripes down their flanks —

and, at their center, a thicket of specialized brown

hairs with a honeycomb-like texture.

Those spongy hairs contain a poison powerful

enough to bring an elephant to its knees, and are

central to recent research by the biologist Sara

Weinstein, which confirmed ideas about how this

rat makes itself so deadly.

The rats sometimes chew on the branches of a

poison arrow tree and spit them back out into their

fur, giving themselves a chemical armor that may

protect them from predators. The ritual turns them

into the world’s only known toxic rodents and

ranks them among the few mammals that borrow

poisons from plants.KATHERINE J. WU

UNEDIBLE YOU

Chewing the Fruit of a Poison Tree

Gives This Rodent a Toxic Outlook

STEPHANIE HIGGINS

Few things on the island of Hawaii are more valu-

able than fresh water, even though it receives

plenty of rain. The trouble is that much of it that

does accumulate on the island’s surface disappears

before it can be used.

But a new study reveals that underground rivers

running off the large island’s western coast are a

key force behind this vanishing act.

Fresh water is often pumped on the island from

aquifers formed from rain at higher elevations

where it is easy to access. The drawback is that if

too much water gets pumped, little remains to

travel through rocks to farms and the ecosystems

that depend upon it. And other studies have re-

vealed that these aquifers are also heavily leaking

somewhere else. “Everyone assumed that this

missing fresh water was seeping out at the coast-

line or traveling laterally along the island,” said

Eric Attias, above, a researcher in Hawaii, who led

the study. “But I had a hunch that the leak might

be subsurface and offshore.” MATT KAPLAN

WATER, WATER NOT EVERYWHERE

Off Hawaiian Island, Trying

To Put a Finger on a Water Leak

UNIVERSITY OF HAWAII