Posts tagged "marine biology"
SEAHORSE HEADS ARE PERFECTLY SHAPED TO KILL
The seahorse may appear ungainly,
but seahorses are sophisticated copepod-killing machines.
They may be slow swimmers, but seahorses are amazingly fast when it comes to snatching prey. “A seahorse is one of the slowest swimming fish that we know of, but it’s able to capture prey that swim at incredible speeds for their size,” says Brad Gemmell, research associate at the University of Texas Marine Science Institute. (via Futurity)
IMAGE Credit: Theodore Scott/Flickr) and Brad Gemmell
GIF of seahorse and copepod via Smithsonian)
IF the lower image isn’t animated (thanks, Tumblr), you can see it here.
Read more …
Reporting on “Morphology of seahorse head hydrodynamically aids in capture of evasive prey”
In Nature Communications 4, Article 2840 [doi:10.1038/ncomms3840]
Safety in Numbers? Not So for Corals
"The last 10 thousand years have been especially beneficial for corals. Acropora species, such as table coral, elkhorn coral and staghorn coral, were favored in competition due to their rapid growth. This advantageous rapid growth may have been attained in part by neglecting investment in few defenses against predation, hurricanes, or warm seawater. Acropora species have porous skeletons, extra thin tissue, and low concentrations of carbon and nitrogen in their tissues. The abundant corals have taken an easy road to living a rich and dominating life during the present interglacial period, but the payback comes when the climate becomes less hospitable.”
University of Hawaii (2013, November 15). Safety in numbers? Not so for corals. ScienceDaily.
Silly Acropora cut corners in Evolution class.
Ocean Glow Stick: Sea Worm Emits Strange Blue Glow
One common sea worm has a rather uncommon trick: Chaeteopterus variopedatus – also known as the parchment tube worm for the paperlike tubes it builds for itself and lives within throughout its life — secretes a bioluminescent mucus that makes it glow blue.
Now, scientists are a step closer to understanding the mechanisms behind the worm’s glow.
The parchment tube worm can be found on shallow, sandy seafloors all around the world. Its glow sets it apart from other tube worms, most of whichdon’t glow, and other shallow water organisms, which typically emit green light, not blue.
Green light is more typical of shallow-water bioluminescencebecause it travels farther than any other color on the light spectrum, a useful quality in the turbid near-shore environment.
IN SCIENCE TERMS, JAPAN HAS NO NEED AT ALL TO KILL WHALES
Final arguments from the defence and prosecution were heard in mid-July, and the world court is now considering its judgment. At issue is Japan’s right to conduct its seasonal “scientific” whaling program in Antarctic waters. But the case has involved arguments about how to define science itself.
The legal challenge to Japan has been brought to the International Court of Justice (ICJ) in the Hague by Australia, which has asked the Netherlands-based court to find that Japan’s whaling program is illegal because it is actually commercial whaling — not scientific research that is permissable under the 1982 moratorium on commercial whaling declared by the International Whaling Commission (IWC), which went into effect in the 1985/86 coastal and pelagic hunting seasons.
Allan Boyle, a professor of public international law at the University of Edinburgh, made the claim that if Japan’s current whaling program was not scientific, then neither were the research activities of numerous institutions worldwide that use fisheries data to assess sustainable catch levels.
- More: The Japan Times
- Photo: A Minke whale and her 1-year-old calf are hauled aboard the Nisshin Maru, the world’s only whale-factory ship, in the Southern Ocean in February 2008. In this case, Japan’s ‘legal research’ advertised on the ship’s stern left a large wound from an explosive harpoon in the calf’s belly. | AUSTRALIAN CUSTOMS AND BORDER PROTECTION SERVICE
What gives the sea that smell we love?
It has been known for some time that corals serve as the main producer of dimethylsuphoniopropionate (DMSP), the chemical which acts as the seed for clouds and that gives the sea its unique sent, but until recently it was not known that it was not just the algae living with the coral that produced DMSP, but also the young coral animals, or polyps.
In a paper published in the journal Nature, a documented increase of 54% in the levels of DMSP was observed when polyps were introduced into the setting. “… In fact we could smell it [DMSP] in a single baby coral,” said co-author Cherie Motti from the Australian Institute of Marine Science. The researchers also found that when the temperature of the water was increased the polyps produced ~76% more DMSP. This could be used as an indicator for warming sea temperatures, but would also forewarn a mass die-off of the corals. This is of importance because of the role clouds place in climate regulation in the tropics; if the corals die off because of increasing temperatures less DMSP will be produced and thus less clouds will form leading to an even higher increase in sea temperatures. This is known as a negative feedback loop.
Why Fish Don’t Need to Be ‘Schooled’ in Swimming
How do fish swim in schools, effortlessly coordinating their every move? The answer appears to be ingrained in their genes.
The genetic basis underlying the complex, social behavior of schooling is revealed in two studies published Sept. 12 in the journal Current Biology. The studies suggest that schooling is not a learned behavior, and instead show it relies on several regions of the fish genome.
The findings may point to the genetic underpinning of why humans also are social, and tend to gather in groups, some experts said, although others debated this.
Colorful phytoplankton blooms off the coast of France. Nasa writes:
Blooms can be a blessing to other marine species, as these tiny floating plants often feed everything from zooplankton to fish to whales. But some algae and plankton blooms can turn dangerous, either through the production of chemical toxins or by severely depleting the oxygen supply in the ocean and creating “dead zones” that suffocate marine creatures.
Pulsing corals. Scientists hypothesize that the movement of the coral keeps oxygen from building up near by, improving the availability of carbon dioxide for the photosynthetic algae that the coral rely on. The pulsation also stirs the water to improve nutrient supplies. Only corals of the Xeniidae pulsate.
Read more about the study at Science News.
Cancer detection equipment shows us why some corals resist bleaching
Coral bleaching is a huge problem made worse by global warming. It threatens extremely productive ecosystems that are home to countless marine species. Yet some corals do better than others wen exposed to the same hostile environment. Why is that? Scientists at Northwestern University and the Field Museum of Natural History asked themselves that very question, and they think they found the answer using optical technology designed for early cancer detection.
The researchers discovered that reef-building corals scatter light in different ways to the symbiotic algae that feed the corals. Corals that are less efficient at light scattering retain algae better under stressful conditions and are more likely to survive. Corals whose skeletons scatter light most efficiently have an advantage under normal conditions, but they suffer the most damage when stressed.
The findings could help predict the response of coral reefs to the stress of increasing seawater temperatures and acidity, helping conservation scientists preserve coral reef health and high biodiversity. (source)
So the corals that were the “fittest” (in the natural selection meaning of the word) in the past are turning out to be disadvantaged compared to their less efficient cousins under today’s environment. This is the first research to show that light-scattering properties are a risk factor for corals. Hopefully this will help us devise ways to better protect coral reefs, as they are the most fertile biodiversity hotspots in our planet’s oceans.
The whole study was published under an open access license, so you can read it here.
Squid’s Daily Rhythms Are Controlled by Glowing Symbiotic Bacteria
At nightfall, the Hawaiian bobtail squid digs itself out of the sand and rises into the ocean water like a spaceship taking off. It switches on its cloaking device: glowing bacteria inside its body light up, disguising the squid’s silhouette against the moonlight for any predators swimming below. As sleek a vehicle as it appears, though, the bobtail may not totally outrank its microscopic crewmembers. The bacteria seem to power a clock inside the squid’s body that can’t function without them.
Hiding during the day and hunting at night in shallow Pacific waters, Euprymna scolopes clearly has a working circadian clock. Researchers had noticed, though, that the squid’s light organ—the specialized pocket inside its body that houses its bacterial helpers—seemed to have a rhythm of its own. The Vibrio fischeri bacteria give off fluctuating amounts of light throughout the day, for one thing. And the bacteria have their own daily rhythm of gene expression (when various genes are turned on or off), explains Margaret McFall-Ngai, a microbiologist at the University of Wisconsin, Madison.
McFall-Ngai and her coauthors looked for genes linked to circadian rhythms within the squid. They found two types of “cry" genes, which are known to control internal clocks throughout the animal and plant kingdoms. One gene had a daily cycle of activity in the squid’s head—which is what you’d expect, since animals’ main circadian clocks are in our brains. Other clocks can be elsewhere in the body, though, and this is what researchers found with the second cry gene. It was cycling only within the light organ.
Baby squid, which hadn’t yet collected bacterial friends in their light organs, didn’t show the same cycling. So it seemed that the bacteria themselves were driving the daily rhythms in the light organ. When the researchers let squid fill their light organs with defective, non-glowing bacteria, the cry gene still didn’t cycle properly. This suggested that the glow of the bacteria was the crucial ingredient.