Some people like to say that men are always ready (and eager) for sex. Whether or not that’s true for humans, Stanford University researchers have recently learned that it is the case for certain male fish. Downtrodden male African cichlids, whose reproductive systems are so suppressed that biologists thought the fish couldn’t produce sperm, can successfully spawn within hours of rising to power, according to a new study published in the journal Proceedings of the Royal Society B.

Like many other animal species, a single leader—the biggest, baddest male—runs each group of African cichlids. This alpha male, which often sports vibrant blue scales, monopolizes the females and beats down other, weaker males in the community. (High school, anyone?) Because of this sexual exclusion, subordinate males suffer a noticeable pallor, decreased levels of reproductive hormones, and severely shrunken testes. Essentially, the fish trade sperm production for growth spurts, in hopes of someday overtaking the alpha male. Why waste energy making sperm if you can’t use it, right?

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In this lab image, the toadfish’s twin bladders
are visible in the middle of its body.

There’s nothing like a bizarre fish call to shake you out of your complacency about the universe. With that in mind, we bring you the bottom-feeding three-spined toadfish, which produces its foghorn hoots and guttural grunts by vibrating the muscles around its two swim bladders, the sacs of air that keep it afloat. And these aren’t just any hoots and grunts, a new study reveals—some of these cries have qualities that have been seen the animal kingdom over, from babies’ cries to frog calls to bird song, but never before seen in fish, though fish have been known to make an incredible array of sounds (really!).

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Since Monday’s news that a few thousand birds fell from the sky on New Year’s Eve over Beebe, Arkansas, the world has gone a little crazy with talk of the “aflockalypse”: the mass bird deaths that have been documented worldwide.

Bird die-offs have been reported in not only Arkansas but also in Italy, Sweden, Louisiana, Texas, and Kentucky. Die-offs of other animals, including thousands of fish in Arkansas, Florida, New Zealand and the Chesapeake Bay have also been noted, while dead crabs washed up on UK shores.

Causes ranging from UFOs, monsters (our personal favorite), fireworks, secret military testing, poison, shifting magnetic fields, and odd weather formations have been blamed for the deaths, but researchers are saying these types of die-offs are normal. It’s simply a coincidence that a few big ones happened right around the new year–and once the global media started paying attention to wildlife mortality, we saw examples everywhere.

BoingBoing quotes Smithsonian Institution bird curator Gary Graves on the Arkansas bird die-off that got the conspiracy theory ball rolling:

He doesn’t think these bird deaths are a sign of anything nefarious–or, at least, nothing more nefarious than local people taking it upon themselves to stress out a large roost of “nuisance” birds until it flies away. There’s a head count associated with that kind of thing, he says, and it’s not particularly odd to see a few thousand birds die this way. But, with roosts numbering in the millions of birds, that’s not a large percentage lost. The only thing different in this case, he says, is that the dead birds landed on lawns, rather than in the wilderness.

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Oh Christmas trees, oh Christmas trees, what should we do with your corpses?

Here’s an idea that seems to be working well: Use them as fish habitats. Surprisingly, the trees are prefect for the job, Pete Alexander told The New York Times:

“Christmas trees are perfect — just the right size and weight,” said Mr. Alexander, the fisheries program manager for the East Bay Regional Park District, which is based in Oakland, Calif. “And we get them free, because vendors want to get rid of them.”

After the holidays are over, the group gets leftover trees from vendors, ties a bunch of trees together, and sticks them at the bottom of a lake. The trees quickly grow algae and attract fish to the area–which also attracts fishermen. Every year the workers build a habitat in a new lake, and The New York Times reports that the structures last about five years:

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Like some kind of gruesome confetti, Mother Nature rained down more than 2,000 dead blackbirds on a half square mile of Arkansas on New Year’s Eve.

The birds fell over Beebe, Arkansas, but no one is sure what killed them. At around 11:30 p.m. the reports started coming in from residents of the central Arkansas town–worried citizens described the birds falling, dead, from the sky. The birds showed signs of physical trauma, Arkansas bird expert Karen Rowe told CNN Radio:

“It’s important to understand that a sick bird can’t fly. So whatever happened to these birds happened very quickly,” Rowe told CNN Radio on Sunday. “Something must have caused these birds to flush out of the trees at night, where they’re normally just roosting and staying in the treetops … and then something got them out of the air and caused their death and then they fell to earth,” Rowe added.

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Any culture’s religious ceremonies can seem strange to outsiders: For example, take the indigenous Zoque people of southern Mexico. To ask their gods for bountiful rains during the growing season they head to a sulfur cave where molly fish swim in the subterranean lake. They then toss in leaf bundles that contain a paste made from the mashed-up root of the Barbasco plant, which has a powerful anesthetic effect.

When the stunned fish–which the Zoque people consider a gift from underworld gods–go belly-up, people scoop them from the water and bring them home for supper. This fishy protein helps them make it through until the harvest.

This ritual came to the attention of scientists studying the molly fish, who wondered how the toxic root might be affecting fish populations in the caves. So evolutionary ecologist Michael Tobler and his colleagues did a little field research.

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The ninespine stickleback can communicate with fish friends to figure out the best places to eat, but one thing seems to make otherwise social males disregard the group: sex.

Two researchers have found that, as these male fish prepare to breed, they ignore the group and go off alone to explore their environment in the hunt for food. At the same time, egg-bearing female fish do the opposite, sticking more closely to the pack and copying others’ behaviors to find food.

The researchers from the University of St. Andrews published these findings today in the Proceedings of the Royal Society Series B. They suspect that staying with the group helps save the females from predators and conserve their energy, while venturing out alone might help males find other food sources more efficiently. Coauthor Kevin Laland explains:

“While copying others is less risky, it can also be less accurate, compared to collecting firsthand information. The hormonal changes that cause a male to enter his reproductive phase may also be responsible for this transition to more antisocial behaviour.”

Mike Webster of the University of St. Andrews, who coauthored the study with Laland, invoked the clichéd male driver refusing to ask for directions–but with a twist.

“We are all familiar with the stereotype of males refusing to ask for directions–this might apply to fish too, but only when they are preparing to breed.”

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DISCOVER: Ladies’ Night in Animal Kingdom

Image: Press Office, University of St Andrews

Some damselfish have sensitive stomachs, but they certainly aren’t in distress. They can hold their own, researchers have recently determined, by diligently farming their preferred algae crops.

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Male cichlid fish apparently don’t like what they see in the mirror–in fact, they dislike their own reflections even more than enemy fish, according to new research published in Biology Letters.

Wired writes:

“[The] fish readily attack other males as well as mirror images of themselves, posturing and lunging with the same aggression… the reflection-fighting males show heightened activity in [the amygdala,] a part of the brain associated with fear and other negative reactions in vertebrates, [Stanford University researchers] have found. Tangling with a real male doesn’t stir up that response.”

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See that fish in the video below– that’s a slingjaw wrasse. Looks kind of boring, right? Well as you’ve probably guessed from the headline (or from the name slingjaw), it’s not. Just watch the video.

Via the Telegraph:

Its mouth shoots out like that of the monster in the Ridley Scott film Alien, slinging forward up to half the fish’s body length and engulfing the victim in moments.

The odd beast, found in shallow reef and lagoon waters, feeds mainly on small fish, shrimp and crabs.

The secret of the slingjaw wrasse’s remarkable mouth projection: Unlike most bony fishes, its lower jaw is not firmly attached to its skull, allowing the entire mouth to shoot outward. The foot-long fish isn’t really a threat to humans, but you might want to watch your fingers just in case.

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Video: YouTube / Wainwrightlab