Wikimedia Commons: Per H. Olsen

That’s a mama reed warbler and a baby cuckoo (note that the cuckoo doesn’t fit in the nest). It’s an adorably awkward scene—until you realize how it came about.

European Cuckoos are brood parasites, a.k.a. mooches, who pawn all of their chick-rearing duties off on birds of other species. Female cuckoos lay their eggs in other birds’ nests and the other bird (the host parent) incubates the cuckoo egg alongside their own. When the cuckoo chick hatches, it identifies any solid objects in the nest (eggs or hatchlings) and, using the shovel-shaped dent in its back, shoves its foster siblings out of the nest. The host’s eggs fall to their death and the host mother, left with nothing but a big-ass cuckoo in her nest, raises it as her own.

And they all live happily ever after (except for the chicks that don’t, of course).

Scientists estimate that one-percent of all bird species practices brood parasitism. The strategy enables the mother to devote more time to eating, mating and making more babies (measures of success in ecology) rather than wasting energy building a nest, incubating eggs and feeding and defending her chicks. For the whole plan to work, however, her chicks need to survive and to do that, they’ll need to outcompete their foster siblings. That’s all European cuckoo chicks are doing when they shove the host eggs out of the nest. Sure, they could be nicer about it (cowbird chicks manage to snag more food from their foster parents by simply growing faster than their foster siblings), but they could also be a whole lot nastier.

Meet the African greater honeyguide (Indicator indicator). As an adult, the honeyguide is an “indicator”, that guides people to bee hives. As a chick, it’s a little f**ker, that brutally murders its foster siblings.

Female African greater honeyguides lay their eggs in the underground nests of little bee-eater birds (who make their nests in abandoned aardvark burrows). The honeyguide mama does her best to ensure that her little bundle of joy will thrive with its host parents. She internally incubates each egg for an extra day to make sure that it will hatch before its foster siblings and, when she dumps her egg off in the little bee-eaters’ nest, she punctures all the little bee-eater eggs she can find. The punctured eggs don’t survive, but some eggs avoid puncturing (or are laid after the delivery of the honeyguide egg) and hatch a couple of days after the honeyguide chick. That’s when things turn ugly.

Within an hour of hatching, the little bee-eater chick is attacked by a blind, featherless monster with spear-like hooks on its beak. This monster (the three-gram honeyguide chick) pokes, grabs and shakes its foster sibling for an average of 177 seconds. After a vicious (and apparently exhausting) attack, the little bee-eater chick stops moving and the honeyguide chick stops attacking. The little bee-eater chick dies from internal hemorrhaging and bruising sustained in the attack anywhere from nine minutes to seven hours later.

The little bee-eater parents, who were present during the attack but apparently completely clueless about the murder*, continue to feed and nurture the little s**t as their very own. About a month later, the honeyguide emerges from the nest. Its billhook has grown out into a completely normal, innocent-looking bill.

*In their defense, it is completely dark in their underground nest.

Warning: The following video is very disturbing:

********

In other siblicidal news, I wrote about sandtiger sharks and other baby animals that kill their blood siblings a few years ago. (Here’s the post.) Just last week, Kevin Zelnio (of Deep Sea News fame) found a video of sandtiger shark siblicide. It is horrifically awesome. Check it out here.

Spottiswoode, C., & Koorevaar, J. (2011). A stab in the dark: chick killing by brood parasitic honeyguides Biology Letters DOI: 10.1098/rsbl.2011.0739

Why? Because of a plethora of poop—bird poop, to be exact.

BUT they’re also toxic.

How can an ecosystem thrive and be toxic at the same time?

The answer is quite simple: Poop.

Let me explain… As they travel to Antarctica and back during the winter, Arctic terns (Sterna paradisaea) eat fish. These fish have eaten smaller fish. The smaller fish have eaten plankton. And the plankton has essentially eaten stuff it found in the water—nutrients and industrial pollutants like mercury and cadmium. So, when the terns eat fish, they’re not only getting loads of nutrients, they’re getting some mercury and cadmium too.

While the terns are flying south and then north again, common eiders (Somateria mollissima) are chilling along the coast of Greenland. Here, the birds chow on mussels and clams. As filter feeders, mussels and clams filter suspended particles out of the water column, filling their bellies (and tissues) with good stuff (like nutrients) and bad stuff (like aluminum, lead and manganese). And when the eiders eat the mollusks, they swallow the chemicals along with the nutrients.

Obviously, birds that eat chemical-laden prey will end up pretty chemical-laden themselves, but to understand the true toxicity of these birds, you have to account for biomagnification.

“Biomagnification: Result of the process of bioaccumulation and biotransfer by which tissue concentrations of chemicals in organisms at one trophic level exceed tissue concentrations in organisms at the next lower trophic level in a food chain.”         -Environmental Protection Agency, 2010

In other words, the birds end up with a whole lot of chemicals in their bodies (even more than the levels present in the prey they eat). And because fish-eating terns are higher on the food chain than mollusk-eating eiders, terns will likely carry a greater toxic load than eiders.

Here’s a visual explanation:

And here’s a visual explanation with a giant baby*:

(from http://www.permacultureusa.org/2008/08/13/pesticides-and-you/)

Now back to Nunavut. Every summer, about 300 pairs of Arctic terns convene at one of the Tern Island ponds and between 50 and 100 common eider hens meet at the other Tern Island pond. What do they do when they return to Nunavut after months of eating?**

(from "Everyone Poops" by Taro Gomi)

And what they eat is what they poop (more or less). Both bird populations offload a s***load of phosphorous into their ecosystems. In fact, total phosphorus concentrations in sediment cores taken from both sites were comparable to those found in sewage oxidation ponds. Of course, phosphorus makes things grow, creating the appearance of a healthy ecosystem. The terns further taint their ecosystem with mercury and cadmium while the eiders further contaminate their ecosystem with aluminum, lead and manganese.

And there you have it: two toxic, thriving ponds on an island in Nunavut.

*Please do not confuse this with the old food pyramid. Babies are not to be eaten, even in small quantities.

** They nest too, but, for the purposes of this post, poop is the priority.

Michelutti N, Blais JM, Mallory ML, Brash J, Thienpont J, Kimpe LE, Douglas MS, & Smol JP (2010). Trophic position influences the efficacy of seabirds as metal biovectors. Proceedings of the National Academy of Sciences of the United States of America, 107 (23), 10543-8 PMID: 20498048

Huh?

See Exhibit A: The pebble toad (Oreophrynella niger), a tiny toad that lives on the tops of mesas in Venezuela. When threatened by a tarantula, a pebble toad will curl itself into a ball and throw itself off a cliff.

Our second example comes from an awesome study [Wind-Powered Wheel Locomotion, Initiated by Leaping Somersaults, in Larvae of the Southeastern Beach Tiger Beetle (Cicindela dorsalis media)] that sets out to answer the question that drives the impish behavior of most 10-year olds: What happens if we poke it?

The larvae of the coastal tiger beetle (Cicindela dorsalis media) live in the sand at Cumberland Island National Seashore. When threatened (usually by the wasp Methocha, but in this study, by humans), the larvae propel themselves off the sand and flip through the air. Such roly-poly behavior is especially impressive because, as the authors point out, “leaping represents serious challenges to soft-bodied, elongate, short-legged or legless animals” like tiger beetle larvae.

Here are the details:

“Without benefit of high-speed video, however, a typical wheeling event looks like a brief and violent bout of thrashing on the sand, interspersed with an occasional leap, after which the larva suddenly and rapidly zips along the surface of the sand in a more or less straight line.”

Translation: To the naked eye, a threatened C. dorsalis media larva is a spaz. But with high-speed video we can see…

“When a larva is touched on the head, thorax, or anterior abdomen, it typically jerks or crawls away, threatens with open jaws without arching backwards, contracts its body into a sinuate death-feigning pose, or regurgitates.”

Translation: When you poke the larvae on the head or chest, it pukes, plays dead, bares its teeth or just walks away.

“When a larva is touched on the posterior part of the abdomen (i.e., from the fifth abdominal segment to the tail), it vigorously arches its body backwards so that its head snaps upwards and backwards and its tail (if not pinned to the substrate) arches upwards and forwards… The momentum of the head end coiling backwards causes the entire animal to roll backwards until the tail of the now-coiled animal contacts the substrate. As soon as its tail contacts the sand, the larva attempts to launch itself off the sand by arching its body suddenly in the opposite direction, using its tail as an anchor. The larva now forms a dorsal-side-out loop that rotates forward while in the air, often completing one to several rotations while airborne. When a larva lands on the sand, it typically will either fall over on its side or else start to roll. In the latter case it will either continue to wheel or else relaunch once its tail (or less commonly head) contacts the sand”

Translation: When you poke the larva’s butt (or anywhere near it), it flips, using its tail as a launch pad. When it lands, it stays in its roly-poly position and either rolls along the sand until it topples over or launches itself into another round of flying somersaults.

“This translates to a typical speed of 0.30–0.56 m/s), assuming a larva travels one body length per rotation. Under the high winds of 2007 (>12.5 m/s), we observed larvae that were wheeling faster than our assistant could run on the beach, which we calculated separately to be around 3 m/s.”

Translation: These guys aren’t all that fast under normal conditions, but in winds of almost 28mph they can wheel at a sub-9-minute mile pace.

Harvey, A., & Zukoff, S. (2011). Wind-Powered Wheel Locomotion, Initiated by Leaping Somersaults, in Larvae of the Southeastern Beach Tiger Beetle (Cicindela dorsalis media) PLoS ONE, 6 (3) DOI: 10.1371/journal.pone.0017746

I will try to redeem myself—slowly. I have a whole slew (like five) of completely researched and partially written posts. After careful deliberation, I’ve decided that three of them are keepers. I’ve also decided that if I haven’t gotten around to writing full posts on any of these enthralling topics, I never will. Instead, I hope to lure you back to our blog with three post-ettes.

Eau de Toilette (Literally)

Peeing on mates isn’t all that unique (porcupines do it), but it’s certainly noteworthy—especially in an aquatic environment (a.k.a. a giant toilet).

In two no-longer-recent studies, scientists examined the uri-sexual behaviors of two aquatic organisms. In the first species, the sheepshead swordtail (Xiphophorus birchmanni), the male does the noteworthy peeing. In something known as the “audience effect,” these males pee more in the presence of female sheepshead swordtails than when they are alone.

The authors explain the noteworthiness of this behavior here:

“In order to minimize fluid loss, terrestrial animals must concentrate urine and release it in specific times and places. This basic physiological constraint has facilitated the evolution of spatiotemporal control of chemical signaling in terrestrial taxa. Relatively free of this constraint, however, freshwater organisms urinate more or less continuously. Thus, the remarkable degree of control over the release of chemical signals by male swordtails is likely the result of intense selective pressures on males to transfer important information directly to potential mates.”

Translation: Bladder control is essential for terrestrial animals, but freshwater animals essentially live in their toilet, giving them the luxury of being able to pee non-stop, whenever and wherever they want. The male sheepshead swordtail is therefore a remarkable creature simply because it is potty-trained (with the area surrounding female sheepshead swordtails functioning as the potty).

The second noteworthy pee-er is the female signal crayfish (Pacifastacus leniusculus). Male and female signal crayfish play very different roles in child-rearing (males are deadbeats while females provide sole parental care for six months) and approach mating accordingly (males are sluts, females are selective).

When signal crayfish pee, they release aggressive signals that other signal crayfish interpret as something like ‘I’m gonna f**k you up, biotch’. The female crayfish means it, but when a male gets her message he stops peeing because, well, he thinks her challenge is pretty hot. The two fight and while they fight, the female assesses her challenger. If he’s tough enough to thwart her resistance, they mate.

Berry, F., & Breithaupt, T. (2010). To signal or not to signal? Chemical communication by urine-borne signals mirrors sexual conflict in crayfish BMC Biology, 8 (1) DOI: 10.1186/1741-7007-8-25

Rosenthal, G., Fitzsimmons, J., Woods, K., Gerlach, G., & Fisher, H. (2011). Tactical Release of a Sexually-Selected Pheromone in a Swordtail Fish PLoS ONE, 6 (2) DOI: 10.1371/journal.pone.0016994

Remember back in January when I announced that one of my posts had been selected for Open Laboratory 2010? Well, the wait is over (you’ve been waiting anxiously, right?). Open Lab 2010 is now available in book form (and downloadable pdf form for e-readers).

Buy it here!

If you’re at work (or somewhere where people might peer over your shoulder and judge you), you should read Zinjanthropus’ Adaptationism in the Human Penis first. (There aren’t any pictures in this post, but you will come across gems like this: “Males with better plungers should have more offspring…”)

Then check out Scicurious’ Friday Weird Science: Penises are Funny Looking! (The title comes from something SciMom said in the bean aisle.)

Note: These are serious scientific discussions of the human penis. Of course, they’re funny too because, well, what SciMom said.

In fact, male splendid fairy-wrens are so insecure about their ability to get a female’s attention that they’ve resorted to a technique employed by human boys worldwide: the “scary movie effect.” In other words, they wait until something scary—in this case, the call of a predator—grabs the female’s attention and then they simply let her know that they’re there. And guess what, it works.**

It goes like this: A butcherbird calls. (Butcherbirds, named for their habit of hanging their prey on a hook, are a major fairy-wren predator.) And almost immediately after the start of that call, a male splendid fairy-wren lets out his own call—a type II call. This vocal hitchhiking produces a duet that the female splendid fairy-wren presumably hears as: “Yo” (in the scary voice of a big bad butcherbird) “Hey there pretty lady” (in the sweet voice of a male splendid fairy-wren).

The female responds by looking in the direction of the male splendid fairy-wren, inviting him to flirt with her. He accepts the invitation, showing off with a face fan (a display in which he flares his ear tufts), a seahorse flight (a display in which he undulates between a horizontal position and a vertical position as he slowly lowers himself to the ground and then springs back up into the air) or by accessorizing with pink and purple flower petals.

Male splendid fairy-wren face fan. Wikimedia Commons: Nevil Lazarus

Emma Grieg and Stephen Pruett-Jones, the scientists who studied this behavior, found that female splendid fairy-wrens were more attentive to butcherbird-type II call duets than they were to stand-alone type II calls. They also found that the female splendid fairy-wrens only responded to the duets when the type II call came from an intruding male. If the type II call came from her own mate, she wasn’t interested—even if it followed a butcherbird’s call.

(Yeah, that’s right—her mate. Ya see, splendid fairy-wrens have an interesting social structure. They pair up for life, but they mate predominantly with individuals other than their actual “mate.”)

Wacky morals aside, what is that splendid little bird thinking when he calls attention to himself in the presence of a predator? Grieg and Pruett-Jones aren’t sure, but they suspect that butcherbirds are most dangerous when they sneak up on splendid fairy-wrens in open areas. So when the fairy-wrens are safely tucked away in vegetation and totally aware of the butcherbird’s location, perhaps they’re safe—perhaps even safe enough to flaunt their splendiferousness.

*Imagine if every Tom, Dick and Harry were re-named splendid Tom, splendid Dick and splendid Harry. Just imagine…

**For the birds. Guys, please, if you’re older than 15 do not use this technique on your date. It’s lame.

Greig, E., & Pruett-Jones, S. (2010). Danger may enhance communication: predator calls alert females to male displays Behavioral Ecology, 21 (6), 1360-1366 DOI: 10.1093/beheco/arq155

Most scientific names come from Latin, but Google came up empty when I searched for Latin variations of blenn. Could it be someone’s name (eg. Dr. Blenn)? Again, my search proved fruitless. That left one logical explanation: the original blenny-namer was a toddler. Who else could match a cute little name with a cute little fish?

Anyone who knows Greek, apparently. It turns out that the name blenny isn’t that cute after all. Blenn- comes from the Greek word blennos, meaning mucus. And since there are approximately 833 species in the Blenniidae suborder, there are about 833 species of mucus fish. Nice.

Saber-toothed blenny, William Leo Smith, AMNH

Why the sudden interest in blennies? Well, I came across a paper about saber-toothed blennies. Don’t they sound vicious? Yeah…They’re not. They do have fang-like canine teeth and those teeth are connected to a venom gland. But they only use their built-in weapons to nip skin or mucus off an unsuspecting fish (much like naughty bluestreak cleaner wrasses).

My disappointment in the saber-toothed blenny left me searching for a cooler blenny—a mucus fish that could walk or talk or…leap. Meet the Pacific leaping blenny. These fish begin their lives in the ocean as planktonic larvae and then move to the supratidal zone, which is the rocky, splashy section of land above the high tide line. That’s right, these fish live on land.

Obviously, any normal fish living on land would be totally screwed. First, there’s the issue of breathing. Normal fish use gills to extract oxygen from the water. That same process would work just fine in air if it weren’t for the fragility of the lamellae (the part of the gills responsible for gas exchange). Out of the water, a fish’s lamellae will collapse, rendering gas exchange—and therefore breathing—impossible. To thwart suffocation, Pacific leaping blennies don’t breathe through their gills when they’re on land. Instead, they take oxygen in through their skin.*

Then there’s the issue of mobility. Normal fish swim. Swimming requires water. Critters that live on land tend to walk. Walking requires legs. The Pacific leaping blenny has neither, but such piddly details don’t really matter for a fish that can leap.

In a fantastically titled paper (“A Locomotor Innovation Enables Water-Land Transition in a Marine Fish”), Shi-Tong Tonia Hsieh describes the leaping maneuverability of these talented mucus fish. To launch itself, a Pacific leaping blenny curls its tail towards its head and pushes its tail fin into the ground, propelling itself forward and up at a speed of 1.5 meters/second (3.3 mph). Like this:

Ahem. I can’t embed the video. Click here to see it.

To travel shorter distances on land, they simply hop:

Again, the video issues…Click here to see the blenny hop.

I know what you’re thinking: These fish may be able to hop and leap, but what would they do if there were a vertical sheet of plexiglass in their habitat? Ironically enough, Dr. Hsieh had the same question. Here’s the answer:

Of course, I still can’t embed a .mov video so click here to see it.

*FYI: Walking catfish have a structure that strengthens their lamellae so that they can continue to use their gills on land.

Hsieh, S. (2010). A Locomotor Innovation Enables Water-Land Transition in a Marine Fish PLoS ONE, 5 (6) DOI: 10.1371/journal.pone.0011197