Friday, November 11, 2011

Friday Roundup-Hero Dogs and a Mouthful of Slime

Here are a couple items that caught my attention this week.

1. Rattlesnakes From Abandoned Lots Invade Neighborhood, Terrorize Residents. This sounds like it could be the premise of a reasonably entertaining horror movie. Residents of Port St. Lucie, Florida are convinced that Eastern Diamondback Rattlesnakes are thriving in their neighborhoods because there are too many vacant and abandoned lots. This might be somewhat of an overstatement. Eastern Diamondback Rattlesnake populations are thought be in decline throughout most of their range. If the only thing Eastern Diamondback Rattlesnakes needed to thrive was for people to stop mowing their lawns, the United States Fish and Wildlife Service wouldn't have been petitioned to protect them.

  But, the fact remains that there are Eastern Diamondbacks occasionally showing up where people don't want them. This week, a seven-foot rattlesnake bit a pit bull in someone's yard. Did you do a double-take when you read the rattlesnake was seven feet long? Me too...We'll come back to that in a moment.

  This isn't the first story in the last few weeks to describe a dog being bitten by a venomous snake. And, like these other stories, the owner said that their life had been saved by their heroic dog. I think it may require some imagination to believe that these people were about to be killed by a snake until their dog saved the day (I should make clear here that I wish all dogs involved a speedy recovery and even offer some tips here about how to reduce the chance of your dog getting bitten). Why is it unlikely any human life was in danger? We never even see most of the snakes that are in our yards or under our houses, just because a dog found one and got bitten doesn't mean any lives were saved. Plus, most snake bites occur when people try to handle or kill the snake. The best way a dog could save their human-companion from getting bitten by a serpent is to keep them from messing with it.

This Australian veterinarian has an interesting hypothesis. He says dog-owners shouldn't kill snakes in front of their dog (I assume this happens often when a dog finds a snake), because the dog may learn to try to kill snakes on their own. Perhaps this is a concern when dog-owners get excited after their dog finds a snake, it is easy to imagine that the dog perceives the excitement as a reward.

What's the morale of the story? If you want to avoid getting bitten by a venomous snake, don't rely on hero dogs; train your dog to avoid snakes and do not handle, capture, or attempt to kill snakes yourself.

  Whenever I see a newspaper article about a seven-foot rattler, I know it's a relatively safe bet that the reporter simply took someone's word regarding the length of the snake. It's a common enough occurrence despite many people having surprisingly outrageous ideas regarding how to estimate a rattlesnake's size. We know a seven-foot rattlesnake would be an exceptionally rare and absolutely huge snake. It's not something many people will ever see in their lives. Two days after the original article, a follow-up story now mentions that the snake is three feet long; there is no explanation regarding how the snake shrank four feet in 48 hours.

2. It Turns Out Hagfish Don't Taste As Good As They Sound. Hagfish are an ancient group of animals that live on the ocean floor. For a long time, most people assumed that these creatures, which look a lot like eels, were scavengers, foraging on whatever dead things they could find. But, it is hard to say anything about the natural history of these animals with certainty because it's almost impossible to observe them where they live, i.e. the ocean depths. In this paper, researchers use a bit of modern technology to shed some light on these mysterious creatures. By dropping some bait (and a video camera) into the ocean, a few New Zealand and Australian researchers were able to film some surprising behavior. First are all the attempted predation attempts on hagfish as they swim around the bait. Hafish are interesting in that they are lined with slime pores which exude, you guessed it, a slimy substance. It's long been assumed that this slime deters predators. Now, we can watch this defense mechanism in action. It's a must see. Second, they filmed a hagfish diving into a burrow and extracting a small fish to eat, conclusively demonstrating that they aren't solely scavengers. Check it out.


Much of what I write is based on my experience in the field, however I also rely on the research of others, citations of some relevant scientific articles are below.

Vincent Zintzen, Clive D. Roberts, Marti J. Anderson, Andrew L. Stewart, Carl D. Struthers, & Euan S. Harvey (2011). Hagfish predatory behaviour and slime defence mechanism Scientific Reports, 1 (131)

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