Introducing the spookfish – the first known vertebrate to have evolved mirrored eyes

Researchers from Tuebingen University in Germany have made a startling discovery by finding the first known vertebrate to have evolved mirrors, which focus light into the eyes. This odd vertebrate is a species of fish (Dolichopteryx longipes), commonly known as the ‘spookfish‘ or ‘barreleye‘. Although the spookfish has been recognised for over 120 years, it was only recently (last year) that a live specimen was captured of the coast of Tonga.

The reason for their ellusive nature is that spookfish are resident in mesopelagic to bathypelagic zones (~400 to 2,500m depth), inhabiting the border between the photic and aphotic zones. In order to enhance visual acuity at such depths where sunlight barely penetrates, the spookfish has evolved an elaborate system of two sets of connected double eyes. One half of each eye points upwards, capturing the faint light from the surface, whilst the other half point downwards.


The main eyes of spookfish (with the orange-yellow eyeshine from flash photography) are offset with reflective mirrors (indicated here in black) to focus light from above.

These “diverticular” eyes use an elborate mirror constructed of tiny crystals that focus reflected light onto the retina of the eye. Professor Julian Partridge, a co-author on the paper reasons that this system is the reason that the spookfish thrives in such dimly lit regions of the ocean:

“At these depths it is flashes of bioluminescent light from other animals that the spookfish are largely looking for.

The diverticular eyes image these flashes, warning the spookfish of other animals that are active, and otherwise unseen, below its vulnerable belly.

That must give the fish a great advantage in the deep sea, where the ability to spot even the dimmest and briefest of lights can mean the difference between eating and being eaten.”


When viewed from the top of the head, the mirror inside of the diverticulum (marked with an arrow) is clearly visible through the transparent cornea of the eye.

Nature has evolved some absolutely incredible adaptions to environmental conditions – the really neat thing about this study is that it proves that image formation in vertebrate eyes isn’t limited to refraction, a trait that has evolved in nearly every other vertebrate (including mammals).

“In nearly 500 million years of vertebrate evolution, and many thousands of vertebrate species living and dead, this is the only one known to have solved the fundamental optical problem faced by all eyes – how to make an image – using a mirror” (Link)

Click here to read the full paper in Current Biology.

Harbor seal debunks AGW myth

A harbor seal, presumably from the north Atlantic, showed up in Bermuda this week and effectively debunked the global conspiracy known as AGW (Anthropogenic Global Warming).  William Weaver of the group Americans for Climate Truth said in a statement “scientists have reported that thousands of species were moving away from the equator, but this sighting is proof that animals are now moving towards the equator to escape the current global cooling“.  Weaver added, “this discovery overturns that IPCC “report” and the thousands of “scientific studies” that formerly supported the AGW hypothesis”.

Joel Swathmore of Save The Humans, issued a press release stating “this news comes on top of the fact that it got really freaking cold in my town a few weeks ago.  Both pieces of evidence clearly indicate we are heading into an ice age.  Saint Gore was wrong – the big worry now is how to keep the earth from freezing over. ”

Update (07/01/08): it appears that Michael Duvinak over at the Skeptics Global Warming blog doesn’t have much of a sense of humour… J. Roff

Update II (07/01/08):  OK, if it isn’t obvious, THIS IS A JOKE (although the seal story is real).  But I do think sarcasm is one way we can begin to point out the foolishness of some of the skeptic arguments.  And it isn’t uncommon to see believers of AGW make similarly dopey arguments, essentially confusing weather with climate.  “dude, what about that heat wave – must be global warming!”

Bush establishes three massive marine parks

President George Bush has made good on his commitment to protect large areas of the Pacific from fishing:

WASHINGTON — Parts of three remote and uninhabited Pacific island chains are being set aside by President George W. Bush as national monuments to protect them from oil and gas extraction and commercial fishing in what will be the largest marine conservation effort in history.

The three areas -totaling some 195,274 square miles – include the Mariana Trench and the waters and corals surrounding three uninhabited islands in the Northern Mariana Islands, Rose Atoll in American Samoa and seven islands strung along the equator in the central Pacific Ocean.

It will be the second time Bush has used the law to protect marine resources. Two years ago, the president made a huge swath of the Northwestern Hawaiian Islands a national monument, barring fishing, oil and gas extraction and tourism from its waters and coral reefs. At the time, that area was the largest conservation area in the world.

Read the entire story here

Update: no, this is not a hoax!

Ningaloo Reef under the microscope

r147412_519770ABC News, 5th December 2008

Scientists who recently completed the most comprehensive study of the Great Barrier Reef are now turning their attention to Western Australia’s coast, focussing on Ningaloo Reef.

An Australian Institute of Marine Science study recently found the steepest drop in coral growth on the Great Barrier Reef in at least 400 years, which the Institute attributes to rising sea temperatures and ocean acidification.

The study found that on current trends coral on the Great Barrier Reef will stop growing by 2050.

The Institute’s Dr Janice Lough says scientists are now conducting a similar study on Ningaloo Reef, using coral cores to provide information about the growth of the reef, similar to the way tree rings are used to date trees.

“Some of these should contain records between about 50 to maybe 150 to 200 years, of coral growth at Ningaloo, so we’re really interested to see whether similar slowing of growth is likely to be evident in the West,” she said.

“As with people if you listen to one person they can tell you any old story, if you get a lot of people telling you the same story, or a lot of corals telling you the same story then we will believe what they’re saying, and corals don’t have any axe to grind, they are very objective about what they’re observing in the environment.”

Manta rays

2008 was the year that scientists realised that the humble manta ray (Manta birostris) might not be a a solitary species as initially thought. First described by the naturalist Johann Julius Walbaum back in 1792, the manta ray grows in excess of 7.6m (>25ft) and weighs up to 2300kg (~5,000lbs) – about 4/5ths of the weight of a Hummer SUV.

Andrea Marshall, a PhD student at the University of Queensland has been studying the ecology of manta rays in Mozambique for over 5 years, and his since identified over 900 individuals. Using genetic and morphological markers, her research showed that there are at least two different species of manta ray: the smaller common manta ray (as in the above video clip) specific to coastlines and coral reefs around the globe, and a second larger species of manta ray that is more elusive, and has broad migratory habits.

As Andrea points out, manta populations are frequently small in size, and intense fishing pressure can threaten the stability of local populations in a few years. The more common manta ray is particularly susceptible to unsustainable localised fishing pressures due to their restricted migratory ranges, whilst the larger migratory species causes problems with population estimates and conservation management to it’s broad home range. Manta rays are in increasing danger from the effects of fishing, and cartilidge and branchial plates (the characteristic mandibles or ‘lobes’ that protrude from the mouth) are sold for upto $50USD per kilo in Asia.

mantasatmarket-full1 andreamarketweb-full1

I filmed the video at the top whilst on fieldwork in the central Great Barrier Reef last year. The two manta rays (the smaller ‘common’ type) were feeding on an upwelling of plankton off the edge of the reef crest, and were happy for us to swim between them without being disturbed. Visit the homepage of the the Manta Ray & Whale Shark Research Centre in Mozambique to read more about the conservation and protection of these amazing creatures, or check out their blog (“The latest news on the biggest fishes“) over at wordpress

Nasa climate expert makes personal appeal to Obama

obama_hansen4The Guardian, 2nd January 2008
One of the world’s top climate scientists has written a personal new year appeal to Barack and Michelle Obama, warning of the “profound disconnect” between public policy on climate change and the magnitude of the problem.

With less than three weeks to go until Obama’s inauguration, Professor James Hansen, who heads Nasa’s Goddard Institute for Space Studies, asked the recently appointed White House science adviser Professor John Holdren to pass the missive directly to the president-elect.

In it, he praises Obama’s campaign rhetoric about “a planet in peril”, but says that how the new president acts in office will be crucial. Hansen lambasts the current international approach of setting targets through “cap and trade” schemes as not up to the task. “This approach is ineffectual and not commensurate with the climate threat. It could waste another decade, locking in disastrous consequences for our planet and humanity,” the letter from Hansen and his wife, Anniek, reads.

The letter will make uncomfortable reading for officials in 10 US states whose cap and trade mechanism – the Regional Greenhouse Gas Initiative – got under way yesterday. The scheme is the first mandatory, market-based greenhouse gas reduction programme in the US.

Hansen advocates a three-pronged attack on the climate problem.

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Declining calcification on the Great Barrier Reef – Radio Interview

Glen De’ath and Katherina Fabricius, two co-authors from the recent science paper on the decline in coral calcification on the Great Barrier Reef were interviewed by Australian ABC radio this afternoon. Listen online below, or read on after the jump for a transcript.


update: fixed the link to the correct interview.
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Declining calcification on the Great Barrier Reef

As we’ve covered here before at Climate Shifts, the build up of carbon dioxide in the atmosphere has the potential to slow the growth of reef-building corals by increasing the acidity of the world’s oceans.   By burning immense amounts of fossil fuels, humans have increased the concentration of carbon dioxide (CO2) in the atmosphere by nearly 40%.  Roughly a quarter of this CO2 is being absorbed by oceans, where it reacts with seawater to form carbonic acid, acidifying the upper layers of the ocean.

Porites Cores

X-ray photographs of core sections from a massive coral (Porites lutea) showing annual density banding patterns similar to tree ring growth (Image courtesy of Bob Dunbar, Stanford University)

Several laboratory experiments suggest this could make it more difficult for corals and other organisms such as crabs and clams to secrete the calcium carbonate skeletons they depend on for survival.  The increased acidity essentially makes it more energetically costly to secrete skeletons and could eventually literally dissolve them.

A new research article published today in Science magazine (De’ath et al. 2009) takes the case for ocean acidification a step further.  The article suggests that the recent man-made increase in ocean acidity has lead to a reduced growth rate of massive reef-building corals.  A team of scientists from the Australian Institute of Marine Science measured the growth of hundreds of corals from 69 reefs on the Great Barrier Reef (GBR), Australia.  The team took core samples of the coral skeletons (up to 5m in length) and measured annual growth rings going back over 400 years. Their results strongly indicate that the vertical extension of massive, long-lived corals has slowed by roughly 13% since 1990.  This decrease in growth coincides with an increase in the acidity of tropical oceans. A previous paper from the group published earlier this year (see here) was widely criticized because it was based on corals from reefs close to shore and was limited to two geographic locations. However, the teams new paper found evidence of declines in calcification across over 300 corals growing across 2000 km of the GBR, which is indeed a cause for concern.

Whilst slower growth rates might not seem like a big problem in isolation, reef scientists are concerned that this will exacerbate the impacts of other threats to coral reefs.  Slower vertical growth of corals will make it harder for reefs to keep up with rising sea levels, whilst decreases in calcification makes corals more vulnerable to physical damage such as destructive storms and bioerosion.

Changes in (A) calcification, (B) linear extension, (C) density between 1905-2005 (328 corals from 69 different reefs across the length of the GBR. (D) shows trends in calcification between 1572-2001 (10 corals)

Changes in (A) calcification, (B) linear extension, (C) density between 1905-2005 (328 corals from 69 different reefs across the length of the GBR. (D) shows trends in calcification between 1572-2001 (10 corals). Light blue bands indicate 95% confidence intervals for comparison between years, and gray bands indicate 95% confidence intervals for the predicted value for any given year.

The fact that coral growth since the 1990’s has fallen to its lowest rate for 400 years is particularly worrying, and in stark contrast to the usual inductive reasoning portrayed in the media that “corals grow faster in warm water, therefore warm water is good for coral reefs” (see here for more discussion).

Given that global CO2 emissions are now exceeding the worse-case IPCC scenario, and the likely lag time of several decades between the addition of CO2 and the resulting increase in ocean acidity, we will almost certainly see such problems with coral calcification escalate over the coming decades. We can add this to the list of ‘surprises’ (such as deep water anoxia and the runaway collapses of iceshelves), and strongly suggests that we have seriously underestimated not only the rate of climate change, but the scale of the impacts on ecosystems across the globe. These results should compel the Rudd government to make immediate and drastic steps to decarbonise Australian economic systems as a urgent priority.

Did early climate impact divert a new glacial age?

Are we preventing a new ice age by burning greenhouse gases and increasing CO2 concentration in the atmosphere?  Steve Vavrus presented a study at the annual American Geophysical Union meeting on Dec 17 suggest exactly that scenario.  Furthermore, he suggested that humans started impacting climate thousands of years ago via deforestation and agriculture.

SAN FRANCISCO — The common wisdom is that the invention of the steam engine and the advent of the coal-fueled industrial age marked the beginning of human influence on global climate.

But gathering physical evidence, backed by powerful simulations on the world’s most advanced computer climate models, is reshaping that view and lending strong support to the radical idea that human-induced climate change began not 200 years ago, but thousands of years ago with the onset of large-scale agriculture in Asia and extensive deforestation in Europe.

Using three different climate models and removing the amount of greenhouse gases humans have injected into the atmosphere during the past 5,000 to 8,000 years, Vavrus and Kutzbach observed more permanent snow and ice cover in regions of Canada, Siberia, Greenland and the Rocky Mountains, all known to be seed regions for glaciers from previous ice ages. Vavrus notes: “With every feedback we’ve included, it seems to support the hypothesis (of a forestalled ice age) even more. We keep getting the same answer.”

Link to the full article on EurekAlert here