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Monday, 14 February 2011

The miracles of the ocean

First check out those amazing fishes left over the 2004 tsunami (RIP to all of the people who died back then!).

It's unbelievable how little we know of the life in the deep waters of the ocean.
Today:

  1. Virgin birth: sharks' secret survival trick
  2. Future of commercial whaling ban rests with Japan
  3. "Human rights" urged for whales and dolphins
  4. Faecal attraction: Whale poop fights climate change
  5. New study documents use of hormone progesterone in simple microscopic aquatic animals

Virgin birth: sharks' secret survival trick

In parthenogenesis, females' eggs start dividing without being fertilised. This produces daughters that are genetically similar to the mother. It was first observed in a captive hammerhead shark in 2001, but this was an isolated incident, and the shark pup died after three days, making it difficult to say much about its evolutionary significance.
Kevin Feldheim at the Field Museum in Chicago, and an international team of colleagues, have now shown that the incident was not exceptional and sharks born from a virgin mother can survive for many years (Journal of Heredity, vol 101, p 374).
The team were inspired by the 2001 birth to keep eggs produced by a captive white-spotted bamboo shark at the Belle Isle Aquarium of the Detroit Zoological Institute. The female had never encountered a male during her adult life and biologists had assumed the eggs were infertile. To their surprise seven incubated eggs produced two pups that survived five years before they were transferred to another facility. Genetic analysis confirmed that they were parthenogens.
"This suggests that parthenogenesis is a viable shark survival strategy," says Paulo Prodöhl of Queen's University Belfast, UK, who is investigating a possible case of virgin birth in the whitetip reef shark.
Modern sharks have been on Earth for several hundred million years. One theory is that switching from sexual reproduction to virgin birth might have helped these ancient creatures survive so long. Several shark species live in single-sex groups and he says parthenogenesis may have ensured that isolated populations of females could survive without males. source
My comment: I am absolutely amazed by large sea-creatures as whale and sharks these days. Try reading in wikipedia about the orca in Wikipedia. It's amazing how evolved those creatures are socially. And now the virgin birth of sharks put everything on a whole new level. And any way, imagine if this mechanism exists in the oceans, what could  happen if it existed (or exists) in humans too. Too bad we don't have a good way to evaluate what's the chance of this happening.

Future of commercial whaling ban rests with Japan

June 18, 2010 By JAY ALABASTER , Associated Press Writer
(AP) -- A quarter-century ban on commercial whaling - one of the world's most successful preservation agreements - could crumble altogether if conservationists cannot persuade Japan to cut back on the tradition it champions.
Delegates to next week's meeting of the International Whaling Commission in Morocco will consider whether to allow limited commercial hunts if Tokyo stops pursuing in a southern sanctuary. Even adamant opponents are willing to sanction limited hunts on that condition, but it appears to be more than the Japanese are willing to concede.
"Japan holds the key, because Japan is the only country that is whaling in the southern ocean, the only country whaling in the sanctuary, the only country doing high-seas, long-distance whaling," said Susan Lieberman, Director of International Policy at the Pew Environment Group, which supports allowing some whaling.
At stake is the future of the IWC, the world's sole whaling regulator. After whaling devastated many species, the commission instituted a ban in 1986, but Japan, Norway and Iceland harvest animals annually under its various exceptions.
Japan maintains more scientific analysis is required in the region. It mostly catches Antarctic minke , aiming for about a thousand per year but often catching far less due to protesters.
Two whaling officials at Japan's powerful Fisheries Agency, which sets the national agenda on whaling issues, said the country will not give up its Antarctic hunts, with one calling them "crucial." Both asked to remain anonymous because they weren't authorized to speak publicly.
Japan's refusal to give up its Antarctic hunt puzzles even observers within the country. Current coastal catches, also conducted for scientific research, provide fresher meat and are cheaper. IWC approval would allow whalers to switch to commercial hunts and chase bigger whales, as well as shield Japan from international criticism.
 source
My comment: I sincerely don't get it why Japan are so adamant on whaling. Seriously, why? They don't earn that much and I really don't understand what they use the killings for! It's not money. People even in Japan wonder what's going on. And yet, they continue to hunt. Why? For poor stubborn nationalism? That makes no sense. And considering how intelligent whales are, I think this really equal murder.

"Human rights" urged for whales and dolphins

OSLO (Reuters) – Whales and dolphins should get "human rights" to life and liberty because of mounting evidence of their intelligence, a group of conservationists and experts in philosophy, law and ethics said Sunday.
Japan, Norway and Iceland, the main whaling nations, oppose such arguments that would outlaw hunting or even keeping the mammals in marine parks. They have long said there is no real evidence that they are smarter, for instance, than cows or pigs.
Participants at a University of Helsinki conference said ever more studies show the giant marine mammals have human-like self-awareness, an ability to communicate and organize complex societies, making them similar to some great apes.
"We affirm that all cetaceans as persons have the right to life, liberty and wellbeing," they said in a declaration after a two-day meeting led by the Whale and Dolphin Conservation Society (WDCS).
Thomas White, director of the Center for Ethics and Business at Loyola Marymount University in California who was at the Helsinki talks, said dolphins can recognize themselves in a mirror, an ability rare in mammals that humans only acquire at about 18 months of age.
Hal Whitehead, a biology professor at Dalhousie University in Canada and an expert on deep-water whales, said there was more evidence that whales have human-like culture.He said that sperm whales have sonars to find fish that are so powerful that they could permanently deafen others nearby if used at full blast. Yet the whales do not use sonars as weapons, showing what Whitehead called a human-like "sense of morality."
Nations in the International Whaling Commission will debate a proposal to approve limited hunts for 10 years by the main whaling nations at a meeting next month, relaxing a 1986 moratorium imposed after many species came close to extinction. sourceMy comment: I don't understand how you can compare an orca with its complex social structures and habits with a cow or dog. Dogs are intelligent, but it's because they live very close to humans and they learn from us and imitate us. While whales and dolphins do not imitate us, they exist on their own and yet they show amazing signs of intelligence. And I don't understand why they should be hunted. I have absolutely no interest in eating such meat (as well as probably 90% of the Western World) and I don't want to use cosmetic products or other stuff obtained by killing them (something probably 70% of the Western World will agree). Then why should those 3 nations have the right to kill whales?! With what they are more different? And I don't understand how could the citizens of those countries agree with such monstrous acts. Because I doubt there are many people who can firmly say they don't believe in whales and dolphin's intelligence.

Faecal attraction: Whale poop fights climate change

June 15, 2010 
Southern Ocean sperm whales are an unexpected ally in the fight against global warming, removing the equivalent carbon emissions from 40,000 cars each year thanks to their faeces, a study found on Wednesday.
In a heroic calculation, Australian biologists estimated that the estimated 12,000 sperm whales in the each defecate around 50 tonnes of iron into the sea every year after digesting the fish and squid they hunt.
The iron is a terrific food for phytoplankton -- marine plants that live near the ocean surface and which suck up CO2 from the atmosphere through photosynthesis.
As a result of faecal fertilisation, the whales remove 400,000 tonnes of carbon each year, twice as much as the 200,000 tonnes of CO2 that they contribute through respiration.
By way of comparison, 200,000 tonnes of CO2 is equal to the emissions of almost 40,000 passenger cars, according to an equation on the website of the US (EPA). source
My comment: Hehe, this puts the idea of the harmony in Nature on a whole new level. :)
  

New study documents use of hormone progesterone in simple microscopic aquatic animals

June 14, 2010
Barely visible without a microscope, rotifers eat algae and serve primarily as food for baby fish. But the females of certain rotifer species can do something quite unusual: they can reproduce asexually by creating clones of themselves, or they can initiate a process that allows sexual reproduction by producing male rotifers.
The chemical mediator for this change from asexual to sexual reproduction turns out to be progesterone - a simple molecule that also plays a vital role in regulating reproduction and in humans and many other species. Finding this sex steroid and its receptor in simple rotifers suggests that the progesterone signaling technique dates back hundreds of millions of years.
The study is believed to be the first to document the use of progesterone in the lineage of simple animals that includes rotifers - and has been largely unchanged for millions of years.Most animals reproduce sexually, a method that makes a species more adaptable by facilitating the elimination of bad genes and creating potentially beneficial new gene combinations. Very simple organisms, such as bacteria, reproduce through cell division and obtain new genetic material from the environment.
The rotifer species Brachionus manjavacas is somewhere in between. During most of the year, the rotifer population consists only of females, which reproduce by creating clones of themselves. But when unfavorable environmental conditions threaten - such as the loss of algae food - about a third of the rotifer population switches to sexual reproduction, which is the only way the creatures can produce eggs able to survive through a long winter.
Kubanek and her collaborators wanted to understand what was triggering that change, which begins with the production of male rotifers. The switching appears to depend on a pheromone protein that the rotifers release into the water to indicate that other rotifers are nearby. When the rotifer population grows large enough to create a significant concentration of that protein, females start laying eggs that can develop as males. A population large enough to do that usually doesn't build up until fall in North America - when winter and the end of the algae food supply are near.
Beyond explaining how chemical signaling mechanisms crucial to both rotifers and humans evolved over time, the research can also help researchers understand the interplay between the environment, metabolism, hormones and behaviors.
Though the researchers were looking for progesterone in the rotifers, finding the same molecule that is essential to humans still came as a surprise.
 source
My comment: Interesting, huh? I think that if progesterone appear in such simple organisms and in humans unchanged, maybe it has some much deeper meaning and use. Because otherwise evolution wouldn't keep it unchanged over the million of years. Very very interesting. And yeah, I really like how the ladies produce males when they decide they need them. So cool! : )

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