Did you know there’s a whale with a horn like a unicorn?

The narhwal (Monodon monoceros) is an arctic whale, closely related to the beluga whom it resembles.

Like the beluga, it has teeth though it doesn’t use them for chewing.  All but two of the teeth are vestigial but one of those, the left canine, grows though the male’s upper lip spiraling counter-clockwise, straight out, in a single tusk as much as nine feet long.

The tusk is not a sword.  Instead, like our teeth it’s made up of layers but it’s hollow inside and much more sensitive.  The outer layer is permeable, allowing seawater to pass through the dentin into the hollow core filled with millions of nerves. Scientists know the tusks can sense salinity but they probably can sense a lot more. When narwhals surface to breathe and rub tusk to tusk they’re not fighting, they’re communicating.

Narwhals are so specialized it may lead to their extinction.  They live only in the Arctic Ocean where they depend on its icy habitat for food and shelter.  They roam in pods of 5-10 individuals and may migrate in groups of 1,000 but they seem more loyal to their favorite sites than to following their food.  As climate change heats the water and melts the arctic ice, narwhals will have less food and fewer places to live. Like the polar bear, narwhals are threatened by climate change.

If or when this whale goes extinct it may pass into mythology, like the unicorn.

(photos from Wikimedia Commons. Click on the images to see the originals)

19 January 2016

A hawk perched on a pig? Well, almost. A caracara on a capybara.

The bird is a yellow-headed caracara (Milvago chimachima), a member of the falcon family native to South America(*) and similar in size to a Cooper’s hawk.

The mammal is a capybara (Hydrochoeris hydrochaeris), the world’s largest rodent. Its scientific name is Greek for “water pig.”  Its English name means “eats slender leaves” in the extinct Tupi language of Brazil.

Semi-aquatic, vegetarian, and closely related to the guinea pig, capybaras swim a lot.  They eat grass and aquatic plants which fortunately wear down their continuously growing teeth.  They also eat their own feces to get more nutrition out of their partially digested food.

Capybaras are big.  They stand as tall as a German shepherd but of course they’re not the same shape and they weigh a lot more.  For a sense of scale, here’s a group of capybaras grazing in a park in Brazil.

These groups are typical.  Capybaras are very social and live with 10-20 and up to 100 other individuals.  The round bump on their snouts is a scent gland called a morillo which they rub on everything to say “I’m here.”  They also use anal scent glands and urine for the same purpose.  Obviously capybaras do not make good pets.

As for the bird, why is the caracara on the capybara?

More on that tomorrow (here).

(photos from Wikimedia Commons. Click on the images to see the originals.)

(*) Both the bird and the mammal have expanded their range into southern Central America.