Quick hitters...

...from Science Daily.

Did a comet impact the receding Laurentide ice field 13,000 years ago, triggering a global cooling that reversed the retreat of the glaciers? Astronomer Bill Napier thinks so.

Analysis of a juvenile Diplodocus skull in Pittsburgh's Carnegie Museum of Natural History suggests that the dinosaur underwent fairly dramatic changes during development.

We know about bioaccumulation of heavy metals in predators, like birds and fish. How about in carnivorous plants, which can be negatively impact by feeding on contaminated insects?

Fish o' the Day - Atlantic cutlassfish

Here's one that many people aren't familiar with, although it's actually very common in our coastal waters. The Atlantic cutlassfish, Trichiurus lepturus, is often called the ribbonfish. They're unscaled, with a smooth, silvery skin. They have large eyes, and the mouth is equpped with (usually) four barbed teeth in the front. As the mouth would suggest, they're carnivores, feeding mainly on small fish. The body is greatly elongate, tapering to a pointed tail.

Cutlassfish can reach a length of 5 feet, although half that is a pretty good-sized one. They're very common inshore, particularly during the summer months, where they're famous for stealing bait. Cutlassfish are supposedly delicious, although I don't know anyone who's tried one. In China, there's an important cutlassfish fishery. In this country, they're most often used as bait for more desirable fish like king mackerel.

Dogs and us

Very nice slide show from ScientificAmerican.com illustrating the relationship between characteristics of dog breeds and what their genetics is telling us about the human condition. Check it out.

Case in point

My conservation biology group is discussing the value of biodiversity, including the "option value" of organisms that might have little or no current economic value but could yield significant return in the future - provided we allow them to hang around long enough.

I give you sirolimus, known in medical circles as rapamycin. Rapamycin is an immunosuppressant that has been used to prevent organ rejection in transplant patients - it's proven particularly useful in kidney transplants. That's rapamycin at left.

Recently, researchers have been looking at the effect of rapamycin on increasing lifespan in a number of organisms, including yeasts, the nematode C. elegans, and mice. Now, a new study appearing in PLoS One suggests that rapamycin can slow down or block the progression of Alzheimer's disease in a mouse model. The work is summarized here at Science Daily.

Pretty significant stuff, but how does it relate to biodiversity? Well, rapamycin was first isolated from the soil bacterium Streptomyces hygroscopicus, first collected in a soil sample from the island of Rapa Nui, known to you as Easter Island. The question is, how many potentially life-saving organisms have gone under the axe or plow before we got to them? And what would they have been worth?

Fish o' the Day - goblin shark

It's late, and I don't feel good. So, I'm cheating a little on Fish o' the Day by using a couple of videos. But here it is, Mitsukurina owstoni. The goblin shark is a deepwater species, found typically at depths of about 250 m. Although they're best known from the Pacific near Japan, they're apparently cosmopolitan. They even make it into the Gulf - one was captured by a commercial trawler about 100 miles south of Pascagoula. This one, from a depth of about 1000 m, was estimated to be between 5 and 6 meters in length, considerably larger than the norm.

Take a look at this video from an aquarium specimen. Check out the strongly heterocercal caudal fin.



A typical size for a goblin is about 10 feet, and they can weigh over 300 pounds. Their most intriguing feature, of course, is the protrusible jaw beneath the distinctive rostrum. They use it to feed on a wide range of prey, including fish, cephalopods, and crustaceans.




Our boy has quite the cult following on the net, too. I don't guess that's too surprising.

Here's a thought...

...for all the global warming deniers. Ain't happenin'. Global temps aren't increasing. I mean, how could they be? It snowed in Florida this year, for crying out loud! But, here's the deal. It seems that global warming's equally evil stepsister, ocean acidification, may have to be denied as well. You see, about 30% of all that carbon dioxide goes straight into the ocean, leading to acidification. About 0.1 pH points since the beginning to the industrial age. For all you non-chemists out there, that's more than it sounds like. Trust me.

Significance? Well, a great many of the things that live in the ocean, like corals, have skeletons built of calcium carbonate. Mix calcium carbonate and acid and what you get is a non-skeleton. The result could be a crash of oceanic ecosystems. Given the amount of oxygen production that comes from those ecosystems, we should probably pay attention.

Wouldn't worry too much about it, though - Glen Beck is on the job.

Fish o' the Day - chain pickerel

A fish of my youth, and one that I haven't seen much of lately.... The chain pickerel, Esox niger, is one of several North American members of the Family Esocidae, commonly known as the pike family. The common name comes from the chain-like pattern on their sides. The larger members of the family, the northern pike and the muskellunge, are more northerly species, although muskies have been introduced in the Tennessee and Tallapoosa River drainage systems. Down here, we have Esox niger and a smaller relation, E. americanus.

Chain pickerel like relatively clear lakes and streams with abundant aquatic vegetation. They're ambush predators, hanging almost motionless near weedy edges, head facing open water, while they wait for small fish to swim by. They're piscivorous for the most part, although they'll take pretty much anything they can catch.

As a kid, I used to catch chains routinely - down in the Florida panhandle we called them jackfish. They always reminded me of a freshwater barracuda, not only with the elongate body and mouthful of impressive teeth, but with their ambush style of feeding as well.

We don't get many pickerels in our Sumter County sampling. When we do, they tend to be the smaller grass pickerel (Esox americanus). One helpful way of distinguishing them is that, while each has a "teardrop" beneath the eye, that of the chain pickerel tends to be almost vertical while the grass pickerel's slants to the rear.

This summer, we'll be broadening our sampling into some of the oxbows off the Tombigbee - hopefully we'll find chain pickerel there.

Pointin' the White Dog north...

and rolling into the darkness with a van full of young recruits. Continuing a Tom Russell theme... tonight we ride.

E. O.

Inspiring as usual. The message was the same, but it matters a lot to hear it from the guy who wrote the book. Literally. A moment - when asked by a student at the close of the talk about the potential impact of global warming on biodiversity, an obviously tired Wilson simply asked three rhetorical questions - "Is it real? Yes. Is it gonna get worse? Yes. What will be the impact on biodiversity? Bad."

He shared a remarkable photo of himself at 13 collecting in Mobile, where he was the first to spot the invasion of imported fire ants. I had hoped to find that image, but couldn't. I did find this, Ed Wilson the Eagle Scout in Brewton, AL. Enjoy.

Fish o' the Day - lancetfish

Now, for something completely different. The lancetfish are two species in the genus Alepisaurus, the longnose lancetfish A. ferox and the shortnose lancetfish A. brevirostris. They are the only living members of the family Alepisauridae. I wasn't familiar with the animals until I was having dinner one night at a restaurant in Pensacola, and they had one on the wall. They are remarkable looking things, sometimes exceeding 2 meters in length, with long fangs and a broad sail-like dorsal on an elongate body.

They are (as far as we know) among the largest of the wholly mesopelagic fishes, where they are voracious predators. In fact, quite a few midwater fish species are know only from their occurrence in lancetfish stomachs. Their somewhat flaccid musculature suggests that they are likely ambush predators, hanging in the water until suitable prey comes within striking distance. We know them best as bycatch in tuna fisheries, although an occasional specimen washes up on the beach.

Heroes

Off to see one. If you're not familiar with contributions of Edward O. Wilson, here's a place to start. The photo at left is from last year, when my band of pilgrims met Dr. Wilson at the Association of Southeastern Biologists meeting in Birmingham.

Fish o' the Day - lesser electric ray

The lesser electric ray, Narcine brasiliensis, like it's larger cousin the torpedo, has a pair of elongated electric organs in the broad pectoral disk. They are found in coastal waters in the western Atlantic, where they may bury themselves in the sand. We see them regularly in trawl samples from Mississippi Sound, and on snorkeling expeditions in Florida lagoons. They top out at about 2 feet in length, although half that is more common. They're sluggish swimmer, propelling themselves primarily with their caudal fin rather than using the pectorals like most rays. Their preferred diet seems to be annelid worms and other inverts. They don't generate much of a wallop, perhaps 30 volts. Still, there are tales of them knocking people down. Not sure how - about all I've ever gotten out of one is a joy buzzer effect.

Jack Rudloe wrote about lesser electric rays in his Wilderness Coast - here it is.

Thinking about rivers...

And another one - from the Red Rock

I can't help but wonder if there were new dinosaur descriptions almost daily before I started keeping up with them. Regardless, here's a contribution from the red rocks of Utah. A new paper in PLoS One, summarized here at Science Daily, reports the discovery of Seitaad ruessi, a sauropodomorph from the Early Jurassic. This species was 10-15 feet long, and would have stood 3-4 feet tall at the shoulder. Of course, the sauropodomorphs would ultimately include the giant sauropods like Diplodocus that were over 100' in length.

The etymology is interesting - Seit'aad is a Navajo word for a monster from the Navajo creation legend that swallowed its victims in sand. The manner in which Seitaad ruessi is preserved suggests that it met exactly that fate about 185 million years ago.

Thanks for the heads-up, Gerald.

Darter people

My guys are working hard on darter distributions. It's a work in progress, but they're making headway.

Roadrunnersaurus

The interpretations assigned to this new dinosaur find seem more speculative than usual, although that's likely due to the incompleteness of the fossil find. Still, Xixianykus zhangi was apparently a speedy little bugger. He was a tiny (maybe half a meter long) Late Cretaceous member of the alvarezsaurs, the same group that included Tyrannosaurus and Velociraptor. The structure of Xixianykus' hind legs, with its disproportionately short femur in comparison to the bones of the lower leg, suggests that it was ideally built for a cursorial lifestyle. Surprisingly, this is also in keeping with its likely feeding behavior. Unlike their larger and more famous cousins, Xixianykus didn't feed on giant herbivores or misbehaving genetic engineers - in fact, they probably craved termites. While we don't know anything about the forelimbs of X. zhangi, those parts have not been recovered, similar species are in possession of short, strong arms with a single large claw. Based on similar structures we see in extant animals, paleontologists believe that these little dinosaurs used their long claw to tear open logs and nests in search of their insect prey. The researchers also feel that a termite-feeding lifestyle is in keeping with Xixianykus' built-for-speed body. Living termite-feeders often have to make long treks between meals - the ability to move quickly would shorten travel time and also lessen the likelihood of falling victim to one of their larger cousins during the trip.

Here's the paper, in Zootaxa.

Spring Break at Small Southern U.

but things are still hopping. Trip to Big Southern U. tomorrow night to see E. O. Wilson speak on "Biodiversity and the Future", then off to Huntsville on Wednesday to accompany student researchers to the Academy meeting.

Spent a good day on the river with Dr. B., running outboards in preparation for the summer field season. Gorgeous day, but a cold Tombigbee wind has me headed for a springtime cold.

Fish o' the Day - starry flounder

Introducing a new feature as I prepare for my Biology of' Fishes course this summer. Seemed appropriate to start out with a fish I know well (or, at least, used to know well). The starry flounder, Platichthys stellatus, is a common flatfish found around North Pacific coastlines. They reach lengths of almost 3 feet, and can weigh almost 20 pounds. The species epithet (and the common name) refers to the banded pattern of dorsal and anal fins. I first got to know starrys during a stint at Oregon State's School of Oceanography, and then later focused a portion of my PhD. work on the utilization of meiofaunal prey by post-larval Platichthys stellatus.

Although starrys belong to the Family Pleuronectidae, the right-eye flounders, they can actually occur in either right-eye or left-eye forms. For the unitiated, that's a reference to the side of the fish that actually faces upward - right-eye flounders lie on the bottom on their left side and their left eye migrates across the body during development. As adults starrys can be found in the coastal ocean, but they're more often associated with estuarine environments. We collected them in the Columbia River estuary when I was in Oregon. In Alaska, we collected the juveniles on intertidal mudflats in Auke Bay.

Nature, yet again

Fascinating video from Nature podcast, which I've been unable to imbed. The Gulf pipefish, it appears, is not the perfect dad that he and his relatives have been painted to be. Rather, they may selectively abort offspring they're brooding.

Also in Nature...

...the breaking news about a possible human relative identified by DNA analysis of a finger bone found in a Siberian cave. Discovered in 2008, the bone had been assumed to belong to one of hte Neanderthals that had lived in the region. Initial analysis indicates that it represents another hominid species. This means that there may have been (at least) four Homo species living across Asia in the latter part of the last ice ago - Homo sapiens, the Neanderthals, Homo floresiensis as indicated by the "Hobbit" find in Indonesia, and this new species in Siberia. Of course, for the time being, caution is warranted.

A fish with a heart

And it's a heart that has lots to tell us. The ability of some fish to regenerate heart tissue is, for obvious reasons, of great interest to us humans. A new paper appearing in Nature describes work done with zebrafish in which researchers have identified a group of heart cells that may provide the secret to this regenerative ability. The hope is that there may be clues here that can allow the human heart to repair itself after injury.