Ask Your Weird Animal Questions: Venomous Mammals, Octopus Mothers

Do echidnas have venomous spines similar to a platypus that can be used in defense? —John McMillan, Metung, Victoria

There are two echidna species—the long-beaked echidna, which lives on the island of New Guinea (map), and the short-beaked, which is found on New Guinea and Australia. Both funky little mammals lay eggs, among a very small group that does so.

A photo of a short-beaked Echidna
A short-beaked echidna forages for food in South Australia in 2013. Photograph by Jürgen & Christine Sohns, imagebroker/Corbis

Like its egg-laying cousin, the platypus, male short-beaked echidnas have venomous spurs on the backs of their hind legs that get bigger during mating season. (Related: “Spiky Baby Killers: Echidna Secrets Revealed.”)

But “unlike the platypus spur,” which is used to inject venom into potential predators, “the echidna spur is not attached firmly to the heel and can’t be used aggressively,” said National Geographic explorer Stewart Nicol of the University of Tasmania, who has spent 18 years tracking and studying the short-beaked echidna.

Instead, “we think [the spur’s] main role is in producing pheromone-like compounds,” said Nicol, who was a co-author on a 2013 PLoS ONE study about the echidna spur.

By the way, echidnas do brandish what are called “spines” on their bodies, like hedgehogs, but they’re actually harmless hairs.

Added Nicol: “They are wonderful animals to work with because they don’t have teeth and they are completely unaggressive.”

[In regard to Longest-Living Octopus Found, Guards Eggs for Record 4.5 Years]—Is it possible that she ate some of her eggs in order to survive? —Alexandre Beaudry

Probably not, said Jennifer Mather, an octopus expert at Lethbridge University in Alberta, Canada.

“Never say never,” of course, but female octopuses stop eating when they are brooding eggs, Mather said. “They’re programmed to turn off eating because they don’t have anything to eat for. That’s quite weird to think about, but it’s true,” Mather said. (See “Social Octopus Species Shatters Beliefs About Ocean Dwellers.”)

Even if they did eat, their digestive gland shrivels, so they couldn’t process the food.

Mather said this is a smart system, because female octopuses don’t need to leave their eggs to hunt—making sure more offspring survive.

I have armadillos in my backyard … Are they destructive? Just asking to know what kind of measures I should take. —Gloria, Florida, U.S.A.

How do you distract (armadillos) from an area, e.g., digging under a mobile home? —Sue, Canada

Jim Loughry of Valdosta State University in Georgia said that armadillos—nocturnal, burrowing animals—will dig for “ants, beetles, earthworms, [and] just about anything in the soil layers.” That behavior may leave bare patches in a lawn or garden.

The fact that the mammals are diggers makes them tough to keep out, he said. (Related: “World Cup Mascot: Explaining the Armadillo.”)

“There’s not a whole lot that you can do to permanently keep armadillos out of your yard without [going to] some kind of extreme expense,” Loughry said.

For instance, a homeowner could build a fence that goes into the ground a couple of feet deep, but very few people are “going to do that just to keep out an armadillo.”

Loughry has heard of people using pepper spray-type chemical repellents or even electrical fences, but pets or children could run afoul of those. Shooting armadillos just leaves a space open for another animal to get in.

In the long run, he said, it might be best to just let these armored critters feast and move along.

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Wildlife

Liz Langley is the award-winning author of Crazy Little Thing: Why Love and Sex Drive Us Mad and has written for many publications including Salon, Details and the Huffington Post. Follow her on Twitter @LizLangley and at www.lizlangley.com