True...

...been derelict the last couple of days. Real world intrudes.

Fish o' the Day - southern brook lamprey

OK, maybe a little bit of a stretch. But, in the eyes of most people, it's got fins, lives in the water, breathes with gills - fish. They're not bony fish, true. They're not even in the Chondrichthyes with the cartilaginous sharks and rays. But we're still gonna call 'em fish.

When most people think of lampreys, the one that comes to mind is the parasitic sea lamprey, Petromyzon marinus. The sea lamprey is an anadramous species that has become landlocked in the Great Lakes and rained down havoc on freshwater fish there. But not all lampreys are evil-doers like P. marinus, and the southern brook lamprey, Ichthyomyzon gagei, is a pretty unassuming member of the clan. It's a small, nonparasitic species that's actually fairly common in many of our streams. They reach a length of 7-8" and live in small to moderate streams, typically over sand or gravel bottoms. They spend most of their lives as a larval form known as the ammocoete, which burrows in the substrate and filter feeds on detritus and diatoms. After a three year larval period, the ammocoete metamorphoses into the adult form, which spawns and dies.

This comes up as the result of the efforts of a couple of my field guys, who returned from working a local stream today with the report of an escaped "eel". The little guy, it seems, slipped out through the mesh of the seine. Now, we certainly have eels in our rivers and streams. But the size of the escapee (a few inches), the location (a shallow riffle over a gravel bottom), and the time of year (most of the literature has Icthyomyzon spawning starting around this time), makes me think they probably had a close encounter with a newly metamorphosed lamprey. Sorry, guys.

Birds are good

Well, insectivorous birds - and bats and lizards and all the other guys that eat the insects that eat plants. You might think it's obvious that animals that feed on plant-eating insects would be good for the plants. And yes, that was widely believed. Until some researchers made the point that birds that eat insects also eat things like spiders and other insect predators. So, there has been some question as to whether insectivorous birds might help protect plants, or might actually be harming them by removing more significant insect predators.

A new study in the Proceedings of the National Academy of Sciences summarizes the results of more than 100 studies and reaches the conclusion that, on the whole, insect-feeders are a net positive for plants.

New one

My Con Bio guys are discussing the fact that, while most new animal species are things like insects and nematodes, there's still the occasional big, new vertebrate. Here's one. A new paper in Biology Letters describes a 6 foot long fruit-eating monitor from the Phillipines. Of course, there's already a sign of trouble. The new lizard, named Varanus bitatawa, was first observed when scientists photographed a local hunter with one he had killed for food. They're apparently an important part of the diet of the indigeneous people in the area.

Fish o' the Day - redfin darter

Seems like time to talk about one of our darters. For the last couple of years, we've had undergrads out in our local streams pulling seines. For the most part, they've been conducting developing research projects for their ecology class, although we've had a few that have been out freelancing. For the most part, the focus has been on microhabitat studies - looking at the way that environmental parameters influence the darter assemblage in a particular stream. We find a good stream, identify a number of microhabitats that differ in current velocity, substrate, canopy cover, etc., and then sample the heck out of them to see what types of darters are there. Darters lend themselves well to this type of analysis, because they're what we have come to call "hunker down" fish. They're strictly benthic - even lost their swim bladder to demonstrate their commitment to life on the bottom. They also show a high degree of site fidelity. That means that if you find them somewhere, it's probably because that's where they want to be. In the process, we're building a decent picture of how different darter species are distributed.

Meet the redfin darter, Etheosoma whipplei. He's a handsome guy - and that's the breeding male that's pictured. They develop a distinctive pattern of red dots, and the banding of the dorsal fins really stands out too. Like most darters, they're small - three inches is a big one.

What our Sumter County studies are telling us is that the redfin is also a pretty capable guy. We find them in a wide range of microhabitats, and in a wide range of streams. We've worked abot ten streams now, and the redfin has been present in all but one. He's there too, we just haven't found him yet.

This must have been one cool place...

...we talked a while back about the crocodilians that might have been food for the gigantic snake Titanoboa in the 60 million year old rain forest habitat preserved in Colombia's Cerrejon coal mine. Now, researchers have found a new species of fossil turtle, Cerrejonemys wayuunaiki , that had a shell the thickness of a dictionary.

Actually, the most interesting thing about the find is that it helps answer some biogeographic questions about the turtle distributions. The closest living relatives are found in various South American river basins. Except for one. In Madagascar. The find provides support for the idea that the group originated in South America prior to its separation from modern-day Indian and Madagascar some 90 million years ago.

Turtles die...

...as the result of commercial fishing operations. A lot of them. That's not news. But a new study appearing in Conservation Letters suggests that the numbers may be considerably higher than we suspected. Bycatch studies indicate that some 85,000 turtles were accidentally taken between 1990 and 2008. Given that the data collected represents a microscopic fraction of the world's fishing fleets, the author's estimate that the actual toll may be as much as two orders of magnitude higher.

Can sea turtle mortality be avoided? Not completely, and there's certainly a cost to the fishermen. Personally, I don't mind paying a little more for my seafood if it means that we don't kill 10 million sea turtles in 20 years.

Great...

Another piece of significant evidence regarding the earth's climatic history that can now be completely misunderstood or (more likely) misrepresented by the global warming deniers.

We've known for quite some time that changes in the eccentricity of the earth's orbit have played a role in the earth's climatic history. Actually, orbital eccentricity has been considered to be part of the puzzle, along with changes in axial tilt and the precession of the axis have all been lumped together to explain what are commonly called Milankovitch cycles (after the Serbian who first postulated the climatic connection). Definitely not my field, but if I interpret this correctly, Dr. Lisiecki is suggesting that the roughly 100,000 year cycle of glaciation that the earth has experienced over the last million years or so is largely explained by changes in orbital eccentricity.

That's great. The problem will come when some Exxon lackey touts this as evidence that climate change is not anthropogenically induced. Over geologic time, have there been climatic changes that man had nothing to do with? Of course. Is the current warming trend the result of human activity? Absolutely.

Fish o' the Day - pirate perch

Here's a nice one. The pirate perch, Aphrododerus sayanus, is deep-bodied, with a perch-like appearance as suggested by the common name. However, the single arching dorsal fin gives them away. In fact, this is the only living member of its family, Aphrododeridae. Adults are typically 4-5" long, and are usually a fairly uniform brown. They're found in slow-moving streams and ponds in most of the major Eastern drainages - we get them in backwater areas off of a number of the streams we work. Pirate perch are actually a rather unassuming-looking fish, until you look more closely. The unique thing about them is the placement of the urogenital opening. As pirate perch mature, the cloaca moves progressively toward the anterior end of the fish - in mature individuals, it's in the throat region. Of course, when we see something like that we want to know why. For a while, it was assumed that the fish must be mouth- or gill-brooders, but no evidence was found.

A 2004 paper in Copeia seems to have provided the answer. Pirate perch spawn in tangled underwater root masses. The females push their head into the tangle, and release the eggs through their forward-placed urogenital opening. Males then follow suit, and fertilize the eggs.

Something we'll play with this summer in the fish class.

On the verge of losing one

The striking looking fellow at left Astrochelys (Geochelone) irradiata, the radiated tortoise. They're native to southern Madagascar, and are generally considered to be one of the most handsome of the tortoises. They're also one of the most endangered. A new report from conservation groups reports that, due to widespread hunting for meat and illegal trading for pets, the radiated may be extinct in 20 years. The team, after extensive field work, reports that areas that once teemed with tortoises now harbor few or none. Locals shared reports of poachers carrying truckloads to local markets. Perhaps most troubling is that poachers are apparently entering protected areas in search of the tortoises, and that the understaffed refugues are helpless to prevent them.

Genome for the birds

The second avian genome to be sequenced is in, Australia's zebra finch (Taeniopygia guttata). The only other bird to be sequenced is the chicken. The work appears in Nature, and is summarized here at Science Daily. Zebra finches can serve as a good model for understanding the way that humans learn to vocalize. Baby songbirds learn by hearing - initially they babble, not unlike human infants. As they listen to adult songs (almost exclusively the male parent) they learn to mimic the songs.

The researchers in the zebra finch genome study were able to show that some 800 genes in the zebra finches arsenal are involved in the act of singing. Not all of these are protein-coding genes; some two-thirds control the production of non-coding RNA which is involved in the regulation of other genes. Since learning to vocalize is a phenomenon found in some of the most complex organisms, it is believed that these non-coding RNA molecules may play a major role in that evolutionary process.

Fish o' the Day - goonch catfish

Posting the Fish o' the Day a little earlier than usual, because of broadcast schedules. It's a tip of the hat to all my guys that are "River Monsters" fans. If I'm not mistaken, they're rebroadcasting the goonch episode tonight (I'll be watching the Yankees and Red Sox open the MLB season - first things first). But, I've got to admit that a television program dedicated entirely to big, nasty freshwater fish is something of a dream come true.

The goonch, Bagarius yarrelli, is one of four living species in the catfish Family Sisoridae. But let's back up for a second. The catfish comprise the Order Siluriformes, and they're an interesting group taxonomically - there are some 36 families (the number changes depending on where you look) containing more than 3,000 species. About one out of every ten vertebrate species is a catfish. The catfish that American's are familiar with, channel catfish and their relatives, are in the Family Ictaluridae. That's a diverse enough group, ranging from tiny madtoms to the giant blue cats and flatheads. It's also North America's largest group of endemic fishes. The other catfish that most of us have some familiarity with are aquarium fish - things like upside-down catfish and glass cats. They're all in other families.

Back to the goonch... All of the Bagarius species are found in rivers of Southeast Asia. B. yarrelli is pretty widely distributed, although it's best known from Indian rivers. It reaches lengths of 6 or 7 feet, with rumors having it much larger (don't they always). Goonch migrate in schools, apparently following schools of giant barb (Catlocarpio siamensis) as they migrate upriver.

The goonch's notoriety comes from sketchy reports of attacks on humans in the Kali River, believed to have been brought about when the fish developed a taste for human flesh after feeding on corpses disposed of from funeral pyres along the river banks. That's where "River Monsters" Jeremy Wade comes in. The attacks on humans are almost certainly exaggerations or fabrications, but it makes for dramatic television. Take a look and judge for yourself. It's on Animal Planet. I'll be watching C.C. and Josh.

Worth keeping an eye on

A Chinese ship has gone aground off Northeastern Australia is and is leaking oil near the Great Barrier Reef.

Life finds a way

A lake high in the Argentinian Andes, almost 3 miles above sea level. Hyperalkaline, with a pH of 11 and salinity five times that of seawater. Loaded with arsenic, low in oxygen, and pounded with high intensities of ultraviolet radiation. And sitting in an active volcano with sulfurous gases escaping from vents. And teeming with life.

Fish o' the Day - banded pygmy sunfish

These little guys, Elassoma zonatum, are one of six species (all in the genus Elassoma) in the Family Elassosomatidae. Contrary to what their common name suggests, they are not true sunfish (Family Centrarchidae). They have cycloid scales, and no lateral line. While some of the pygmy sunfish reach lengths of 3 inches or so, E. zonatum tops out at around 1 1/2 inches. They're pretty distinctive (the males, at least) with their pronounced vertical bands separated by yellowish gaps. We usually find them in swampy areas, often backwaters off streams. There's a particular beaver pond we sample that's loaded with them. They like a lot of vegetation - in fact, that's where they deposit their eggs. They feed on small inverts, and will adapt to dried prepared food. In fact, they do pretty well in aquaria.

We usually find them in swampy areas with little or no current, often backwaters off of streams. There's one particular beaver pond that we sample that's loaded with them, and they can be collected by seining in the littoral vegetation. It takes a trained eye to see them, though - they're that small.

Night music...

...from Billy Bragg, Wilco, Natalie Merchant, and the great Woody Guthrie. Ain't nobody...