LEAPING BUGS, LIZARDS AND SHARKS
My update on the revenge of the whales last week reminded me that the ‘animals’ file is bulging so follow along as we enter the wild and sometimes wacky world of animals.
STRAIGHT AS AN ARROW (OR BENT LIKE A BOW)
Our first story concerns the insect known as the froghopper. They are also called spittlebugs because they encase their young in a frothy white foam that protects them against predators.
We all know that fleas are often considered the champion leapers of the world but fleas can’t hold a candle to froghoppers. These little guys can jump more than 100 times their own body length. If I could do that, I could soar over the length of a football field and come down considerably farther out than the opposite goal post. And if I did it straight up, I could jump over most of the hotels in Tumon.
So, what’s the froghopper’s secret? New research reveals that they achieve their prowess by flexing bow-like structures between their hind legs and wings and releasing the energy in a catapult-like action.
The researchers have discovered that a froghopper stores energy by bending a paired bow-shaped part of its internal skeleton called a ‘pleural arch’. This structure is made from layers of hard cuticle and a rubbery protein called resilin. When the froghopper contracts its muscles to jump, these arches flex like a composite archery bow, and then spring back to catapult the froghopper forward with a force that can be over 400 times its body mass.
There are other similarities between the froghopper’s jumping mechanism and the design of composite bows used in archery. Pairing a rigid and an elastic material means that the skeleton of a froghopper, or an archery bow, can resist damage even if they’re bent for a long time. Froghoppers can hold their pleural arch in a bent ‘ready position’, ready to jump at a moment’s notice, and can jump repeatedly without damaging their bodies.
More often than not, we discover that Mother Nature has beaten us to the punch in our designs and inventions. Here’s to the froghopper, the champion jumper on old Mother Earth!
An adult froghopper. (Credit: Burrows et al, BMC Biology 2008)
I’m not sure if we have froghoppers here in the Marianas, but I think I’ve seen their spittle nests. We certainly don’t have the next animal subject here, but we do have a close relative which makes this story all the more interesting.
IT’S IN THE BITE
An international team of scientists led by Dr Bryan Fry from the University of Melbourne have used sophisticated medical imaging techniques to reveal that the Komodo Dragon (Varanus komodoensis) has the most complex venom glands yet described for any reptile (including snakes), and that its close extinct relative Megalania was the largest venomous animal to have lived.
"These large carnivorous reptiles are known to bite prey and release them, leaving the prey to bleed to death from the horrific wounds inflicted. We have now shown that it is the combined arsenal of the Komodo Dragon’s teeth and venom that account for their hunting prowess. The combination of this specialized bite and venom seem to minimize the dragon’s contact with its prey and this allows it to take large animals," said Dr Fry from the Department of Biochemistry and Molecular Biology.
This is in direct contrast to most information, which holds that Dragon victims die from septicemia caused by toxic bacteria living in the Dragon’s mouth. Komodo Dragons are native to Indonesia, and adult males can weigh up to 250 pounds and grow to 10 feet long. They have around 60 highly serrated teeth that are frequently replaced during their lifetime.
The researchers conducted a comprehensive study of the Komodo Dragon bite, that included using computer techniques to analyze stress in a dragon’s jaws and compare their bite strength to crocodiles. The dragons were found to have much weaker bites than crocodiles, but magnetic resonance imaging (MRI) of a preserved dragon head revealed complex venom glands and specialized serrated teeth which create deep lacerations for entry of the venom.
The researchers located and surgically removed the venom glands from a terminally ill Komodo Dragon at the Singapore Zoo, and used mass spectrometry to obtain a profile of the venom molecules. The team also analyzed which toxin genes were expressed in the dragon’s venom gland.
The venom was found to be similar to that of the Gila monster and many snakes. Its primary effect is that it’s a vasodilator. The venom causes a severe loss in blood pressure by widening blood vessels, thereby inducing shock in the victim. These findings may explain many observations that Komodo Dragon prey become still and unusually quiet soon after being bitten. The bite wounds also bleed profusely, consistent with the discovery that the venom is also rich in toxins that prolong bleeding.
The researchers also examined fossils of the Dragon’s giant extinct relative Megalania (Varanus priscus). From similarities in skull anatomy, they determined that this twenty-five foot long lizard apparently had a similar venom and bite system, making it the largest venomous animal to have ever lived.
Komodo dragons are the largest lizards in the world. (Credit: iStockphoto/Anna Yu)
And of course, we have our very own Varanus species here in the Marianas. Varanus indicus is more commonly known as the hilatai or monitor lizard. They’re also called iguanas, but these bad boys aren’t even closely related to the iguanas of the eastern Pacific. They are, however, close first cousins of the Komodo Dragon. We all know how they got their spots, but I wonder if anyone has ever looked to see if they also have venom glands?
And now a story about animals in unexpected places.
HOW CAN YOU HIDE SOMETHING THAT BIG??
Scientists have finally solved the mystery of the disappearance of the world’s second largest fish. No, it didn’t go extinct, it was just gone for six months of the year. Read on!
Researchers have recently discovered where basking sharks – the world’s second largest fish – hide out for half of every year. The discovery revises scientists’ understanding of this iconic species and highlights just how little we still know about even the largest of marine animals.
Basking sharks are commonly sighted in surface waters during summer and autumn months, but their disappearance during winter has been a great source of debate ever since an article in 1954 suggested that they hibernate on the ocean floor during this time. The researchers from Massachusetts Marine Fisheries have helped solve the mystery and completely re-defined the known distribution of this species.
They used new satellite-based tagging technology to discover that basking sharks make ocean-scale migrations through tropical waters of the Atlantic Ocean during the winter, traveling at depths of 600 to 3,000 feet. Their data show that the sharks sometimes stay at those depths for weeks or even months at a time and thus have avoided detection by humans for millennia. Basking sharks are hard to hide. They can be over 30 feet long a
nd weigh as much as seven tons.
The researchers said they were "absolutely surprised" when they first received a signal from the tagged sharks coming from the tropical waters of the western Atlantic, near the Caribbean and the Bahamas. After all, basking sharks have always been considered to be cool-water sharks, restricted to temperate regions.
Several factors make basking sharks a challenge to study. Not only do they disappear for long periods of time, they also feed exclusively on plankton. That means they aren’t at all interested in traditional fishing methods (unlike the whales of last week’s story). And even when the sharks are found closer to the ocean surface, they spend their time in the cool-temperature, plankton-rich waters that limit underwater visibility and make diving difficult.
The findings could have important implications for the conservation of basking sharks, which have shown some signs of dramatic decline in the last half century and are listed as threatened by the International Union for Conservation of Nature.
The researchers also say that their discoveries indicate the Atlantic population – and perhaps the world population – are connected and may constitute a single population. Therefore the global population of basking sharks may be even smaller than previously thought. Efforts to boost basking sharks’ numbers will therefore need to be coordinated on a global scale.
Basking shark. (Credit: Photo by Chris Gotschalk [http://www.piscoweb.org/who/techs/cgotschalk.html], courtesy of Wikimedia
And apparently the answer to “Where does the basking shark go in the winter?” is “Anywhere it wants to!” Do they hide out on the ocean bottom? No, silly, they vacation in the Bahamas! And of course, this also serves as another reminder that there is no Atlantic Ocean or Pacific Ocean or Indian Ocean. There is the World Ocean and humans would be a lot better off if we started thinking of it in that way!
