From C to Carnivore
Science Blogging
Killer Whales kill whales
And other things.
(image from: wikipedia)
Aren’t they adorable? Orcas are beautiful animals and people often try to portray them as nicer animals than they really are (most notably anyone who thinks it is a good idea to keep these animals in an aquarium). Really though, orcas are nasty. That’s not to judge, all predators are essentially nasty. They eat other animals (but then again, so do I).
Increasing evidence has been found however, that killer whales are more vicious than many would have expected.
In a recent paper in Marine Ecology Progress Series it was reported how Orcas hunt and kill Grey Whales calves on their annual migration around Alaska. The Orcas where observed to attack calves and yearlings in deeper waters. The whales only escape is water less than 3m deep where killer whales would not follow. The predation of Grey Whales by Orcas was first noticed when the scientists noticed that the Greys weren’t progressing along towards their feeding grounds through a narrow straight. Where, it turns out, the Orcas lay waiting. Aside from the impact on whale conservation, the predation of other whales by Orcas is interesting because the Orcas also displayed a caching behaviour. Caching is when a predator stores it’s prey somewhere to avoid other predators getting at it, such as leopards caching their kills in trees to prevent lions from scavenging. Orcas drag the dead whale down and presumably store them under rocky overhangs as they were seen returning over several days to feed off their kill. If the kill washes onto the shore, not only will it be scavenged by brown bears, it will be completely inaccessible to the whales. This is the first example of caching behaviour seen in marine mammals.
However, not all Orcas hunt whales. A while ago, there was a paper discussing how killer whales should be divided into several species based on their mitochondrial DNA and now another paper shows how Orcas can be divided into at least distinct populations based on habitat and tooth wear.
(from Ford et al, 2010)
The Orcas that prey on other whales are transients. Residents prey mainly on fish while offshore Orcas probably prey on sharks, as was described in the same papers. Orcas have also been described to prey on penguins, of all things. And even more interesting is how neat the Orcas managed to dissect out the pectoral girdle of one penguin while leaving the not-so-nice bits behind as seen in the picture below:
(from Pitman & Durban, 2010)
And if this wasn’t enough interesting whale information for you, check out Sci’s posts on whale threesomes and whale penises (obviously NSFW!).
Morell, V. (2011). Killer Whales Earn Their Name Science, 331 (6015), 274-276 DOI: 10.1126/science.331.6015.274
Barrett-Lennard, L., Matkin, C., Durban, J., Saulitis, E., & Ellifrit, D. (2010). Predation of gray whales and prolonged feeding on submerged carcasses by transient killer whales at Unimak Island, Alaska Marine Ecology Progress Series DOI: 10.3354/meps08906
Morin, P., Archer, F., Foote, A., Vilstrup, J., Allen, E., Wade, P., Durban, J., Parsons, K., Pitman, R., Li, L., Bouffard, P., Abel Nielsen, S., Rasmussen, M., Willerslev, E., Gilbert, M., & Harkins, T. (2010). Complete mitochondrial genome phylogeographic analysis of killer whales (Orcinus orca) indicates multiple species Genome Research, 20 (7), 908-916 DOI: 10.1101/gr.102954.109
Ford, J., Ellis, G., Matkin, C., Wetklo, M., Barrett-Lennard, L., & Withler, R. (2011). Shark predation and tooth wear in a population of northeastern Pacific killer whales Aquatic Biology, 11 (3), 213-224 DOI: 10.3354/ab00307
Pitman, R., & Durban, J. (2010). Killer whale predation on penguins in Antarctica Polar Biology, 33 (11), 1589-1594 DOI: 10.1007/s00300-010-0853-5
The Amazing World of Hummingbirds (Part II)
The Cost of Sexual Selection
Hummingbirds are amazing fliers. They’re fast and agile. Some species have extremely long tails such as the Red-billed Streamertail, Trochilus polytmus(image on left below).
In species where females investment into offspring is larger, they choose their mate. Thus in many bird species, males compete with each other to be the “prettiest” and in some birds this means having a long tail. This is called sexual selection. (That long tails are selected for by females has been shown in some bird species.)
However, it has also been shown that an overly long tail decreases fitness in some species because a long tail decreases flying ability. If a birds tail is so long that it will die from other causes, such as starvation or predation, because it cannot fly well enough, tails won’t get longer. An equilibrium is reached.
In hummingbirds, where flying seems such an exquisitely honed, perfectly executed skill with amazing accuracy and power, wouldn’t long tails be really in the way? Presumably not, since these animals have them. Therefore a team of researchers set out to do experiments on hummingbirds to work out what the cost of a long tail for flying is. Apart from the Red-billed Streamertail, they also used Anna’s hummingbird, Calypte anna (left image below).
The Amazing World of Hummingbirds (Part I)
Hummingbirds in slow motion
Check out this awesome "behind the scenes” video of hummingbirds. Contains some awesome footage. The full length video is located here but unfortunately I cannot watch it where I am so I don’t know how awesome it actually is.
Use this video to get in the mood for some more exciting info on hummingbirds coming up (hopefully) soon!
Cool New Pictures of Embryos
My chosen speciality is Developmental Biology so naturally this video fills me with excitement.
But this is not only about some pretty cool images but also about the technique. There’s a paper in Science that’s all about taking images of embryos and measuring them. It’s all very technical but it comes with some cool computer generated images made from these measurements.
Olivier N, Luengo-Oroz MA, Duloquin L, Faure E, Savy T, Veilleux I, Solinas X, Débarre D, Bourgine P, Santos A, Peyriéras N, & Beaurepaire E (2010). Cell lineage reconstruction of early zebrafish embryos using label-free nonlinear microscopy. Science (New York, N.Y.), 329 (5994), 967-71 PMID: 20724640
The many (scientific) uses of penguin poop (Part III)
How hard does a penguin push?
Remember to read the newest and indeed first edition of the Carnal Carnival featuring many other stories about poop!
I’ll admit, I didn’t get the idea to post about penguin poop from the cool and well popularised study on tracking them from space. I got it from a very cool talk by Nathan Myhrvold. This is a guy who got rich working for Microsoft and then quit in 1999 do do random stuff with his money. Like take pictures of whale sex, buy T.Rex skeletons and laser mosquitos to help prevent Malaria. However, he’s not an author on this study so no more shall be said about him now. For more information check out this TED talk.
What’s this all to do with penguin poop? Well, he mentions a paper on the forces involved in penguin pooping. Because penguins are protected you cannot just go and measure the forces on a wild penguin. Instead, the authors relied in photographs. They used the previously mentioned Adelie penguin and the closely related Chinstrap penguin (picture below from wikipedia) again both of the genus Pygoscelis.
The many (scientific) uses of penguin poop (Part II)
Tracking penguins in time
Having established where these awesome, possibly cuddly, penguins are, it is time to turn out attention to their history. This is going to be a relatively short post based on a very short article.
Gentoo penguins (from Encyclopaedia Britannica)
Historical records are limited especially concerning animals in remote habitats. If we want to know how many of them there where at a specific point in time, we’re going to have to resort to different measures. That’s what some researchers from the University of Science and Technology in China did.
The many (scientific) uses of penguin poop (Part I)
Tracking penguins in (& from) space
Penguins are charismatic animals with a large role in popular culture. They are seen as cuddly (though personally, I think that penguins are from the dark side). Regardless of personal inclination regarding cuddliness, it is easy to see that penguins are unique animals. Something your average penguin fan will think of less often are penguin droppings. These are sometimes also referred to as guano, meaning they have a high concentration of certain elements such as nitrates and phosphates making it useful as a fertilizer (e.g. bat guano is often mined though this practice is controversial). However, penguin droppings, especially those from flagship-species such as the Emperor penguins are hard to harvest. However, penguin droppings have other uses which inspired this series of posts, here’s part I on tracking penguins in (& from space).
Emperor penguins, adult among chicks (from Telegraph.co.uk)
Newsflash: a possible mechanism for Parkinson’s disease
Mutations in the allele LRRK2 is used to test for Parkinson’s disease. It’s a gain-of-function mutation that causes familial as well as sporadical Parkinson’s. But so far, no one really knew what LRRK2 actually does. Now, a new study shows that pathogenic (=disease causing) LRRK2 prevents the correct function of certain miRNAs.
Those who cannot remember the past are condemned to repeat it.
Remember the baiji dolphin? It was declared functionally extinct only 4 years ago and was the first cetacean to be wiped out due to humans. It was at a time when I was just turning my awareness towards nature and human impact and I remember being struck by the loss of a dolphin species – such a charismatic animal! It was a poster animal for conservation and yet it is gone from the Yangtze River.
"It seems the baiji is the only thing that is not made in China anymore." Robert Pitman, NOAA marine biologist, co-director of the 2006 expedition.
Remember the paddlefish? No? I didn’t either. It’s a giant, freshwater fish from the Yangtze River, growing up to 7m long. The last confirmed sighting of the fish was in 2003. It is listed as critically endangered. Scientists are focusing on a fast-response system in case any specimen turn up as assisted reproduction seems to only way for this species to possibly survive.
Origins of magic: review of genetic and epigenetic effects
Yes, I’m a Harry Potter fan. I read the books obsessively when I was younger. Needless to say, this article in a holiday issue of the BMJ amused me.
One of the twin pairs (identical) used in the study
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