great white

More Sharks to Track

dr. dolittle — Tue, 02 Oct 2012 16:02:55 +0000

More Sharks to Track

While Dr. Barbara Block's team from Stanford University is tagging and tracking sharks in the Northern Pacific (see prior blog), Chris Fischer and his team from History Channel's Shark Wranglers are tracking great white sharks off the coast of Cape Cod...home of "Jaws." You can track these sharks by visiting Ocearch.org.

A great white shark named "Genie" being outfitted with a GPS tracker off the coast of Cape Cod. Image taken by Gretchen Ertl, NY Times.

The goal of this research is to gather data to help protect the animals by learning more about their breeding and migratory habits.

Sources:

The NY Times and Ocearch.org

Follow Dr. Dolittle on Twitter: @DrDoScienceBlog

dr. dolittle Tue, 10/02/2012 - 12:02

Off the prehistoric coast of Panama, a mega-toothed shark nursery

laelaps — Tue, 11 May 2010 12:57:47 +0000

Off the prehistoric coast of Panama, a mega-toothed shark nursery

The jaws of C. megalodon as restored by Bashford Dean for the AMNH in 1909. Image from the American Museum Journal.

My early elementary reading school choices often got me into trouble. Every week I would pass over the recommended, grade-appropriate sections for the few shelves containing the books about dinosaurs, sharks, and alligators - if it was big and hard sharp teeth, I wanted to learn about it. The school librarian was not too pleased with this, even calling my parents in on one occasion to insist that I read something fit for younger children, but I just could not get enough of theropods, crocodylians, and enormous sharks.

Given my love for "cold-blooded killers" (as so many titles described them) it was not very long before I learned about "Megalodon" (formally known as Carcharocles megalodon), an immense shark which disappeared just a million-and-a-half years before human bathers began to wade into the shallows. Perhaps, some books hinted, the giant sharks still lurked in some unknown ocean recess, and a photograph of an array of American Museum of Natural History scientists inside the restored jaws of the shark drove home the point that it could have made of meal of just about anything it wanted. It was one of the most fascinating and terrifying images I had ever seen.

But the AMNH jaws were a bit out of proportion. As directed by Bashford Dean, the famous jaws were reconstructed by assuming that the teeth of the extinct shark would have had the same proportions to the jaw as in the living great white shark (Carcharodon carcharias), yielding a maw that would have fit a shark 100 feet long or more. As scientists learned more about the giant fish, though, they realized that this method had overinflated the size of the shark, with present estimates placing it at the more modest (but still gargantuan) 60 feet +. Despite the large size of C. megalodon, however, the young of this shark would still have been vulnerable to other seagoing predators of their time, and according to a new study published in PLoS One the "mega-toothed shark" may have protected its young by delivering them in nurseries.

Large sharks, such as the great white shark, are apex predators as adults, but they start off small and relatively vulnerable. It is for this reason that some species deposit their young in shallow habitats full of fish and other pint-sized fare, and it appears that C. megalodon did the same. Over the years paleontologists have identified several sites relatively rich in juvenile C. megalodon teeth, including the 10 million year old (Miocene) Gatun Formation of Panama. The marine fossil site preserves a shallow habitat containing numerous C. megalodon teeth and a relative paucity of whale bones (prey for adult sharks that their young probably would not have fed on), and for the first time a team of paleontologists have tested the idea that his place was once a haven for the young predators.

A collection of C. megalodon teeth from the 10 million year old Gatun Formation of Panama.

In order to make the case that the small teeth truly represented juvenile sharks paleontologists Catalina Pimiento, Dana Ehret, Bruce MacFadden, and Gordon Hubbell had to rule out several alternate hypotheses. It might be argued, for example, that individuals of C. megalodon evolved increasing body size over time, meaning that the teeth from the Gatun Formation belonged to small adults rather than juveniles. When the teeth from Panama (both from adults and juveniles) were compared to C. megalodon teeth from the older Calvert Formation of Maryland (14 million years old) and the young Bone Valley Formation of Florida (5 million years old), however, they did not find any sign that C. megalodon was becoming larger over time.

Another possibility was that, because tooth size and shape varies within the jaws of individual C. megalodon, the teeth were just the smaller teeth of large animals. To test this the authors compared the teeth from the Gatun Formation to associated tooth sets of adult and juvenile C. megalodon to make sure they were properly interpreting the position of the teeth and the life stage they represented. What they found was that the teeth truly did come from small individuals and fell within the range expected for juvenile sharks.

To further check their hypothesis, the authors used a previously-published model based upon growth in great white sharks to estimate the length of the Gatun Formation C. megalodon individuals. The results showed that most individual sharks (21) could be categorized as neonates or juveniles as they were under 35 feet in length (with the smallest being about seven feet long), while there were only approximately seven individuals which would have exceeded that length and been categorized as adults. So long as this sample is a true signal of the kind of animals which lived at the site, it would seem that juveniles significantly outnumbers adults, just as would be expected in a nursery.

That a nursery would have provided some protection for the young sharks is inferred from the presence of other teeth found in the Gatun Formation. A seven foot long newborn C. megalodon is still a pretty big shark, but the hammerhead sharks and extinct snaggletooth sharks which lived in the area were even bigger, growing to 20 feet or more. Young C. megalodon would have run the risk of becoming prey for adult members of the species, as well, so despite the fearsome reputation of the species, these sharks were quite vulnerable as newborns. The use of nurseries allowed the young sharks to begin their lives in relative safety until they were large enough to make it on their own, and now that such a site has been identified scientists can use similar criteria to pinpoint other nurseries at fossil sites elsewhere.

Pimiento, C., Ehret, D., MacFadden, B., & Hubbell, G. (2010). Ancient Nursery Area for the Extinct Giant Shark Megalodon from the Miocene of Panama PLoS ONE, 5 (5) DOI: 10.1371/journal.pone.0010552

laelaps Tue, 05/11/2010 - 08:57

AZA Annual Conference - Communicating Wildlife Conservation

zooillogix — Tue, 16 Sep 2008 09:34:38 +0000

AZA Annual Conference - Communicating Wildlife Conservation

Basically this session is about making a media story out of a zoo or aquarium's conservation efforts. I'm making a story out of making a story.

Challenging Media Myths About White Sharks
Speaker: Karen Jeffries, Monterey Bay Aquarium

The Monterey Bay Aquarium examined the possibility of exhibiting a great white shark in an effort to change perceptions of an animal most commonly associated with the movie Jaws. The husbandry challenges were formidable. Of the 37 previous attempts to exhibit a great white, all had died quickly, the oldest living only 16 days.

The PR challenges were also formidable. Not the least of which, was the need for a robust "crisis communications" plan, in the event that the shark died, or a diver got nipped while cleaning. They also took a proactive PR approach within the aquarium, stationing a speaker directly in front of the exhibit at all times. This speaker spoke to both the behavior and biology of great whites as well as the purpose of exhibiting one: increasing awareness of their plight. Eventually, Peter Benchley even visited as a guest of the Aquarium and said he regretted the damage Jaws had done to the public perception of these incredible animals.

The Monterey Bay PR folks also made an effort to "rebrand" the "great white shark" simply as a "white shark."

The Aquarium finally ran into problems when the white shark began bit a soupfin shark and then, a few days later, killed another soupfin shark (what a delicious name! who can blame him?). This led to public pressure to release the shark, which eventually abated. However, the shark grew rapidly, which increased the challenges of handling the animal as well as its danger to other animals in the tank. Due to these factors, they finally decided to release the shark.

Successfully exhibiting the shark resulted in a measured increase in conservation awareness amongst aquarium visitors, major national media coverage, increased visitorship, and a multi-million dollar commitment from the board of directors for white shark conservation.

MBA White Shark

How to Find Hidden Stories in Your Zoo/Aquarium
Speaker: Kelly Lessard, Minnesota Zoo

A newborn sea turtle was taken from a Florida beach by a Minnesota resident who brought it back as a gift for his girlfriend. The girlfriend turned the sea turtle over to the Minnesota Zoo which used it as an opportunity to educate the public about the importance of not taking animals from the wild. After one year at the Minnesota Zoo, they returned the now 7lb sea turtle to Florida. By alerting Sun Country airlines to this special passenger, they were able to get a free first class ticket for turtle and the United Fish and Wildlife Service animal handler in whose lap the critter was required to ride. Sun Country actually invited local camera crews into the plane to film the turtle in its first class accommodations. Its landing and unloading was also covered by Florida news who turned it into a sort of reverse Elian Gonzales type story.

How to "Field Produce" Stories
Speaker: Holly Braithwaite, Utah's Hogle Zoo

Holly is talking about how the news cycle has gotten incredibly short, how right she is.

I hope she forgives me for not covering her presentation in more detail, but it is more about PR than it is about specific stories from the Hogle Zoo, so I'm gonna hold off.

The Good, the Bad, and the Fuzzy - Spider City Comes Alive!
Speakers: Jason Jacobs and Kirsten Perez, Los Angeles Zoo

Leveraging their proximity to Hollywood and the coincidental launch of the movie Spider Man 3, they decided to launch Spider City Comes Alive! with a 3D comic book theme that would tap into enthusiasm for the movie without getting them sued. Big idea was to demonstrate that spiders were both heroes and villains. They managed to get Stephen Kutcher (bug wrangler to the stars, previously featured on Zooillogix) to come in and present for the opening. They even created a Spider City comic book.

Spider City Ad

zooillogix Tue, 09/16/2008 - 05:34

Ocean Life After Dark…A Pair of Steamy Shark Stories

zooillogix — Tue, 07 Aug 2007 17:18:00 +0000

Ocean Life After Dark…A Pair of Steamy Shark Stories

In two tantalizing shark discoveries, scientists in Germany have learned that playing certain songs to sharks in aquariums increases their libidos. Meanwhile, a different group of scientists may have discovered the secret rendezvous spot where great white sharks go to mate.

Bon-Chicka-Bow-Wow

Out of sheer frustration with the lack of sexual behavior in their captive sharks, researchers in German aquariums tried playing different music to the fish, hoping that it would help put them in the mood. The same tactic has proven successful with captive panda bears and primates in the past, and lo and behold it seems to have worked with the sharks as well. According to the scientists the mating habits seem to have increased overall friskiness in the fish. The scientists even tested which songs got the most enthusiastic response from the animals, and here they are, in order of their arousing effect: 1. Salt'n Pepa - Push it, 2. Joe Cocker - You Can Leave Your Hat On, 3. James Last - Traumschiff (title song for German version of the Love Boat), 4. Justin Timberlake - Rock Your Body, 5. Bob Marley - No Woman, No Cry, at least according to this article in Ananova.com.

Meanwhile, according to a paper published in Marine Biology, researchers believe they may have discovered the secret "love motel" where great white sharks go every year to mate. Very little is known about great whites, despite their status as one of the most popular and most feared predators on the Earth. Perhaps one of the greatest mysteries surrounding the beasts is where exactly they go to mate. Great white mating has never been witnessed and has remained in the realm of mere speculation for decades.

Hi my name is Dawn, and I just moved to town. Lol. I'm 18, S/F, and am just looking to make some friends. I like hanging out, listening to my ipod and chilling with my buddies. Check out my pics at my page, and if you like them, maybe we can hang out some time. Lol.

Thanks to sophisticated modern tracking devices, (you saw them on Zooillogix first, boooya!) however, scientists believe they might have found the answer to the mating mystery. Following the movement of tagged sharks, they noticed a spot in the ocean, 1,553 miles west of the Baja Peninsula, where sharks seem to congregate year after year. At first they believed the sharks were feeding there, but according to the paper's author, Kevin Weng as quoted in this article on discovery.com, "It's just not an area that a shark would logically go to from California to find something to eat...No seals or sea lions are there, and it's not a hot area for whales either." The sharks' behavior at the spot is different as well. They seem to dive more often than usual, at an unusual depth of 1000 feet down. Weng believes they are smelling the water to seek out mates. Weng hopes that understanding more about the great whites' mating behavior will help us to understand more about their threatened population and how to save it. Yeah, right....perv.

zooillogix Tue, 08/07/2007 - 13:18