Bite Force of The Great White Shark

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ABSTRACT: The notorious jaws of the white shark Carcharodon carcharias are widely feared, yet poorly understood. Neither its bite force, nor how such force might be delivered using relatively elastic cartilaginous jaws, have been quantified or described. We have digitally reconstructed the jaws of a white shark to estimate maximum bite force and examine relationships among their three-dimensional geometry, material properties and function.

We predict that bite force in large white sharks may exceed c. 1.8 tonnes, the highest known for any living species, and suggest that forces may have been an order of magnitude greater still in the gigantic fossil species Carcharodon megalodon.

However, jaw adductor-generated force in Carcharodon appears unremarkable when the predator's body mass is considered. Although the shark's cartilaginous jaws undergo considerably greater deformation than would jaws constructed of bone, effective bite force is not greatly diminished.

Carcharodon was found that the largest great whites have a bite force of up to 1.8 tonnes. By comparison, a large African lion can produce around 560 kg of bite force and a human approximately 80 kg - making the great white's bite more than 20 times harder than that of a human.

UNSW's Dr Steve Wroe, the study's lead author, says the great white is without a doubt one of the hardest biting creatures alive, possibly the hardest.

"Nature has endowed this carnivore with more than enough bite force to kill and eat large and potentially dangerous prey," he says.

"Pound for pound the great white's bite is not particularly impressive, but the sheer size of the animal means that in absolute terms it tops the scales". From the press release.

Three-dimensional computer analysis of white shark jaw mechanics: how hard can a great white bite?. 2008. S. Wroe, et al. J. Zoology 276: 336 – 342.

She Gods of Shark Reef

I Fought The Tyrannosaurus

From Tales of Suspense #5 (Sept. 1959) comes this story illustrated by Steve Ditko:

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The Perfect Imperfect Body

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Having an imperfect body may come with some substantial benefits for some women, according to a new article in the December issue of Current Anthropology.

The hormones that make women physically stronger, more competitive and better able to deal with stress also tend to redistribute fat from the hips to the waist.So in societies and situations where women are under pressure to procure resources, they may be less likely to have the classic hourglass figure.Cashdan's hypothesis aims to explain a peculiar observation.

Women around the world tend to have larger waist-to-hip ratios—more cylindrical rather than hourglass-shaped bodies—than is considered optimal.Medical studies have shown that a curvy waist-to-hip ratio of 0.7 or lower is associated with higher fertility and lower rates of chronic disease. Studies have also shown that men prefer a ratio of 0.7 or lower when looking for a mate.

The preference makes perfect sense, according to evolutionary psychologists, because the low ratio is a reliable signal of a healthy, fertile woman.But in data that Cashdan compiled from 33 non-Western populations and 4 European populations, the average waist-to-hip ratio for women is above 0.8. If 0.7 is the magic number both in terms of health and male mate choice, why are most women significantly higher?

Androgens, a class of hormones that includes testosterone, increase waist-to-hip ratios in women by increasing visceral fat, which is carried around the waist. But on the upside, increased androgen levels are also associated with increased strength, stamina, and competitiveness. Cortisol, a hormone that helps the body deal with stressful situations, also increases fat carried around the waist.

Trading the benefits of a thin waist for better ability to collect resources may be a good deal in certain societies and situations. link

The Seed of Life Floats Between The Stars

Astronomers have detected a building block of RNA floating within the hot, compact core of a massive star-forming region in the Milky Way. The molecule appears to have formed with all of the other stuff that makes up planets, suggesting that many other worlds are seeded with some of life's ingredients right from birth.

Using the IRAM radio dish array in France, a team of European astronomers has detected glycolaldehyde--a simple sugar that makes up ribose, one of the constituents of RNA--within the core of what appears to be a coalescing disk of dust and gas in a star-forming region called G31.41+0.31, about 26,000 light-years away. The sugar molecule can apparently form in a simple reaction between carbon monoxide molecules and dust grains.

The discovery is significant for two reasons.

1: G31.41+0.31 lies far away from the radiation-filled center of the Milky Way, so if any biological processes start up there, they will have a chance to establish themselves.

2: The abundance of glycolaldehyde in the G31.41+0.31 cloud suggests that the molecule is "common throughout star-forming regions," says astrophysicist and co-author Serena Viti of University College London. The implication is that wherever there is starmaking and planet formation going on, organic building blocks could be assembling as well.

Astrobiologist Michael Mumma of NASA's Goddard Space Flight Center in Greenbelt, Maryland, says it's possible that life's building blocks arrive on planets after this violent period has passed. Glycolaldehyde, for example, seems to be located in an area of the star-forming region where it could become part of comets. If so, Mumma says, some of those comets could eventually deliver the sugar to young planets. From Science Now

First detection of glycolaldehyde outside the Galactic Center. 2008. M.T. Beltran et al. Astrophysics

Ancient Climate Change Influenced Modern Octopus Evolution

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Many of the world's deep-sea octopuses evolved from species that lived in the Southern Ocean, according to new molecular evidence. Octopuses started migrating to new ocean basins more than 30 million years ago as Antarctica cooled and large ice-sheets grew.

These huge climatic events created a 'thermohaline expressway' - a northbound flow of deep cold water, providing new habitat for the animals previously confined to the sea floor around Antarctica.

Isolated in new habitat conditions, many different species evolved. Some octopuses lost their defensive ink sacs because there was no need for the defence mechanisms in the pitch black waters more than two kilometres below the surface.

Megaleledon setebos, the closest living relative of the octopuses' common ancestor. Photo: Census of Marine Life

"It is clear from our research that climate change can have profound effects on biodiversity, with impacts even extending into habitats such as the deep oceans which you might expect would be partially protected from it. "If octopuses radiated in this way, it's likely that other fauna did so also, so we have helped explain where some of the deep-sea biodiversity comes from."

The findings form part of the first Census of Marine Life (CoML), set to be completed in late 2010. It aims to assess and explain the diversity, distribution and abundance of marine life in the oceans, past, present and future. link

The thermohaline expressway: the Southern Ocean as a centre of origin for deep-sea octopuses. 2008. J. M. Strugnell et al. Caldistics, published on-line Nov. 11, 2008

Sea Urchin Hold Secret of Biomineralization

Used to crush food, for structural support and for defense, the materials of which shells, teeth and bones are composed are the strongest and most durable in the animal world, and scientists and engineers have long sought to mimic them.

A new study describes how the lowly sea urchin transforms calcium carbonate — the same material that forms "lime" deposits in pipes and boilers — into the crystals that make up the flint-hard shells and spines of marine animals. The mechanism, the authors write, could "well represent a common strategy in biomineralization."

The sea urchin larval spicule is a model system for biominerals, and the first one in which the amorphous calcium carbonate precursor was discovered in 1997 by the same Israeli group co-authoring the current PNAS paper. A similar amorphous-to-crystalline transition has since been observed in adult sea urchin spines, in mollusk shells, in zebra fish bones and in tooth enamel. The resulting biominerals are extraordinarily hard and fracture resistant, compared to the minerals of which they are made.

"The amorphous minerals are deposited and they are completely disordered," Gilbert explains. "So the question we addressed is 'how does crystallinity propagate through the amorphous mineral?'"

“We found that at 40-100 nanometer amorphous calcium carbonate particles aggregate into the final morphology. One starts converting to crystalline calcite, then another immediately adjacent converts as well, and another, and so on in a three-dimensional domino effect. The pattern of crystallinity, however, is far from straight. It resembles a random walk, or a fractal, like lightning in the sky or water percolating through a porous medium," explains Gilbert.

Vampire Moth Discovered

From National Geographic News:

Only slight variations in wing patterns distinguish the Russian population from a widely distributed moth species, Calyptra thalictri, in central and southern Europe known to feed only on fruit.

When the Russian moths were experimentally offered human hands this summer, the insects drilled their hook-and-barb-lined tongues under the skin and sucked blood.
Entomologist Jennifer Zaspel at the University of Florida in Gainesville said the discovery suggests the moth population could be on an "evolutionary trajectory" away from other C. thalictri populations. This is the second population of vampire moths Zaspel and her team have found. They discovered the first in Russia in 2006.

"Based on geography, based on behavior, and based on a phenotypic variation we saw in the wing pattern, we can speculate that this represents something different, something new," Zaspel said.