Sanctuary Asia – July 2019

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More at http://www.sanctuaryasia.com |Natural History

Crocodiles are known to ingest small stones called gastroliths, which help grind up the food contents in the stomach.

Did You Know?

The Uninvited Assassin

Giant Spiders of the

Antarctic

Invasive species are one of the biggest causes of extinctions

globally. Introduced, intentionally or accidentally by humans,

alien species can wreak havoc for native species. While

some invasives such as cats and rats predate upon some

native species, others compete for resources, while some

can even alter the landscape of the region. The Asian toad

Duttaphrynus melanostictus that was accidentally introduced

from Southeast Asia to the eastern port of Toamasina on the

island of Madagascar, presents a rather precarious challenge.

Like most true toads, it produces toxins through the parotid

glands located on its back, as a defense mechanism against

predators. These toxins impede sodium and potassium levels

in cells, leading to rapid heart failure. In habitats where Asian

toads occur naturally, some predators have evolved a simple

immune mechanism to tackle the toad toxins or have learnt

to avoid preying on them altogether. But, in Madagascar

where no known toad species occured naturally, the endemic

species never had to build resistance against them.. As a

result, the unique and rare fauna of Madagascar is at risk of

getting poisoned by the invasive Asian toad.

The frigid waters of the North and South Poles harbour

some of Earth’s most gigantic marine animals. In the

Antarctic, for example, giant sea spiders Colossendeis

robusta reach lengths of up to 70 cm. In other parts of

the globe, sea spiders, which are related to terrestrial

spiders, are much smaller. These deep-sea dwellers

have neither lungs nor gills to absorb oxygen. They do

so through the skin pores on their legs! As they grow, their

exoskeletons become more porous. This ability gives them

an edge as the oceans warm.

In a study, which was carried out at McMurdo Station

in Antarctica and published in the Proceedings of the Royal

Society of London, researchers found that despite being

large-bodied, giant sea spiders were able to cope with rising

temperatures. This could be because of their highly porous

legs. “The exoskeletons of the really big ones look almost

like Swiss cheese,” said Caitlin Shishido, a Ph.D. student at

the University of Hawai’i.

Sanctuary Asia, June 2019 85

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The Antarctic giant sea spider grows up to 70 cm. in length

and breathes in oxygen through the pores on its legs!

Madagascar's unique and endemic fl ora and fauna are at risk

from the Asian toad that was unwittingly introduced to the

island nation.

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