Tag Archives: animal

Oops! Endangered tuna unwittingly served at sushi restaurants

Yellow fin tuna (Thunnus albacares) and short-beaked common dolphin in a diorama of the eastern tropical Pacific at the AMNH's Milstein Family Hall of Ocean Live. (Image/R. Mickens/AMNH)

Next time you head out to your favorite sushi restaurant, you might want to think twice about ordering the tuna. There’s a good chance the fish on your plate could be an endangered species.

A new study by the American Museum of Natural History conducted DNA investigations on tuna at restaurants in New York City and Denver and found that nearly 30 percent of the tuna tested was actually endangered bluefin, and less than half of that was labeled as such.

A single bluefin tuna can sell for tens of thousands of dollars at market, a popular draw for the fishing industry. But that popularity comes with a price. Western stocks of northern bluefin tuna now hover around 10 percent of their “pre-exploitation” numbers. And last October, the country of Monaco nominated northern bluefin tuna for a listing under a complete international trade ban by the Convention on International Trade in Endangered Species (CITES), according to a press release.

The serving up of a critically endangered fish is not necessarily on the shoulders of the restaurants. They might not know they’re doing it, just as consumers might not know they’re eating it. This is because the eight species of tuna are so genetically similar – closer than humans are to chimpanzees – that even with DNA testing, it’s hard to distinguish the difference, and once tuna arrives to the U.S. market, the U.S. Food and Drug Administration-approved marketing label is simply “tuna.” A new and improved method of genetic detective work just might help change all that.

“When you eat sushi, you can unknowingly get a critically endangered species on your plate,” says Jacob Lowenstein, a graduate student affiliated with the Museum and Columbia University in the press release. “But with an increasingly popular technique, DNA barcoding, it is a simple process for researchers to see just what species are eaten at a sushi bar.”

DNA barcoding can be used to identify what animal became which product, even down to the origin of a leather handbag, according to the press release. In the case of the bluefin tuna, DNA barcoding defines a genetic key of 14 nucleotides exclusive enough to identify whether the tuna being served is bluefin. A similar method has been used to identify endangered whales on the Asian market and wildlife being sold in the African bushmeat trade.

With any luck, researchers will develop a handheld barcoding machine that can be used to identify fish on-site.

This study can be found in the current issue of PLoS ONE.


Vegetarian spider also a smarty pants

Female Bagheera kiplingi

Adult female Bagheera kiplingi eats Beltian body harvested from ant-acacia Photo/R.L. Curry

For ages, ants have had a monopoly on the coveted acacia, protecting the plant from would-be predators in exchange for shelter and food, or so they thought. Skulking in the background, and recently discovered, is an unlikely competitor of the ant — a spider. And this is no ordinary arachnid. The Bagheera kiplingi also happens to be a vegetarian, and is the first of its kind known to science.

“This is really the first spider known to specifically ‘hunt’ plants,” said Christopher Meehan of Villanova University. “It is also the first known to go after plants as a primary food source.”

The veggie-loving tendency of this jumping spider was first discovered in Central America back in 2001 by Eric Olson of Brandeis University. Since then he has teamed up with Meehan, who independently observed the jumping spider in 2007, to learn more about this unusual creature and the extent to which it likes plants. Not only is Bagheera kiplingi the only predominant vegetarian of 40,000 known spider species with plants making up more than 90 percent of its diet, but it’s showing scientists a complex side of arachnid biology and behavior that indicates the spider’s diet is just the beginning of this animal’s surprising life history.

Bagheera defense

Adult female Bagheera kiplingi defends her nest against acacia-ant worker. Photo/R.L. Curry

Ants are aggressive defenders of the acacia plant making life difficult for outsiders who attempt to encroach on their turf. After all, they want those yummy beltian bodies all to themselves. So how is the jumping spider managing to exploit the acacia for both food and shelter?

Science is still trying to figure that out, but preliminary research shows the spiders take advantage of the invertebrate equivalent of run-down real estate, setting up residence in less-than-desirable regions of the acacia. But their ingenuity doesn’t stop there. Bagheera kiplingi are outsmarting their ant foes, said Meehan, exploiting their intelligence and agility to get around the ants. “Individuals employ diverse, situation-specific strategies to evade ants, and the ants simply cannot catch them,” he said.

As if to add insult to co-evolution, the ants may not even know when spiders are in their midst. Bagheera kiplingi literally dupes the ant by baring young that look like carbon-copies of the ants, and Meehan has reason to suspect that the spiders actually wear a sort of insect perfume that makes them smell like their would-be attackers.

More research is forthcoming, including a look at the possibility that spider dad’s help raise the babies, a virtually unheard of behavior in spider biology. In the meantime, I hear Meehan and Olson’s methods included high-definition video of these smarty-pant vegetarian spiders. Now that would be some footage to see.

Meehan and Olson’s study is available in the October 12 issue of Current Biology.


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