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Two More Odd Things I Just Learned About Fish

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When I'm not blogging for mental_floss, I can usually be found wearing bright orange rubber pants and gutting, cutting and selling fish at my local Whole Foods (and winning awards for it). Sometimes, my two worlds collide and I find some scientific research involving my ocean-dwelling friends that begs for a blog post. This is one of those times.

1. Dying Zebrafish Give Their Kids a Powerup
Many animals give off biochemical signals when they're frightened or hurt to warn other members of the species of danger and elicit anti-predator and defensive behavior. The effects of these "alarm substances" on juvenile and adult animals have been the subject of many studies, but researchers at the Marine Biology and Ecology Research Center at the University of Plymouth wanted to know how embryos still in the early stages of development would respond to the substances. [1]

Embryos of two species (Danio albolineatus and D. rerio) of zebrafish, tropical freshwater members of the minnow family native to southeastern Himalayan region, were exposed to skin injury-induced alarm substances from adults of the species and filmed during development. The development time of both species was sped up, and alarm substance-exposed embryos reached their first muscular contractions (D. rerio) and their first heartbeats (D. rerio and D. albolineatus) earlier than control embryos.

The exposure to the alarm substance caused the embryos to developed a functional heartbeat almost 10%, or 1.5 to 2 hours, faster than normal. That might seem like a snail's pace to us, but after fertilization, zebrafish develop precursors to all the major organs within 36 hours, hatch within 48 hours and begin swimming and feeding within 72 hours. Speeding up development by even just an hour reduces the time the embryos are vulnerable in their egg case and possibly not under the guard of their parents.

How will these developmental advances affect the fish later in life? The researchers think they could either be a sign of an increased development rate overall (with the fish rushing through all their developmental stages), or they could relate to later physiological or behavioral traits.

2. Stingrays Are Smarter Than They Look
rayFreshwater stingrays, the tropical river-dwelling relatives of ocean-going stingrays, have, like sharks and other cartilaginous fish, long been thought of as reflexive machines without cognitive capacity and ability (in part because they're difficult to study). Well, we owe them an apology, because they recently joined a very special club: the royal order of animals that use tools.

In an experiment, researchers from the Hebrew University of Jerusalem in Israel designed a plastic tube test apparatus with two openings and placed a piece of food in it.[2] All five of their stingray subjects (Potamotrygon castexi) figured out how to get the food out of the tube with a carefully directed jet of water (which meets the basic definition of a tool), the first indication of tool use in the batoid fishes. That's one small step for understanding the evolutionary origins of cognitive function in higher vertebrates and one giant leap for raykind. Congrats, guys.

[1] S. Mourabit, S. D. Rundle, J. I. Spicer and K. A. Sloman. "Alarm substance from adult zebrafish alters early embryonic development in offspring." Biology Letters. DOI:10.1098/rsbl.2009.0944

[2] M. J. Kuba, R. A. Byrne and G. M. Burghardt."A new method for studying problem solving and tool use in stingrays." Animal Cognition. DOI: 10.1007/s10071-009-0301-5


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Let Alexa Help You Brine a Turkey This Thanksgiving
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There’s a reason most of us only cook turkey once a year: The bird is notoriously easy to overcook. You could rely on gravy and cranberry sauce to salvage your dried-out turkey this Thanksgiving, or you could follow cooking advice from the experts.

Brining a turkey is the best way to guarantee it retains its moisture after hours in the oven. The process is also time-consuming, so do yourself a favor this year and let Alexa be your sous chef.

“Morton Brine Time” is a new skill from the cloud-based home assistant. If you own an Amazon Echo you can download it for free by going online or by asking Alexa to enable it. Once it’s set up, start asking Alexa for brining tips and step-by-step recipes customized to the size of your turkey. Two recipes were developed by Richard Blais, the celebrity chef and restaurateur best known for his Top Chef win and Food Network appearances.

Whether you go for a wet brine (soaking your turkey in water, salt, sugar, and spices) or a dry one (just salt and spices), the process isn’t as intimidating as it sounds. And the knowledge that your bird will come out succulent and juicy will definitely take some stress out of the holiday.

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Big Questions
Why Do the Lions and Cowboys Always Play on Thanksgiving?
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Because it's tradition! But how did this tradition begin?

Every year since 1934, the Detroit Lions have taken the field for a Thanksgiving game, no matter how bad their record has been. It all goes back to when the Lions were still a fairly young franchise. The team started in 1929 in Portsmouth, Ohio, as the Spartans. Portsmouth, while surely a lovely town, wasn't quite big enough to support a pro team in the young NFL. Detroit radio station owner George A. Richards bought the Spartans and moved the team to Detroit in 1934.

Although Richards's new squad was a solid team, they were playing second fiddle in Detroit to the Hank Greenberg-led Tigers, who had gone 101-53 to win the 1934 American League Pennant. In the early weeks of the 1934 season, the biggest crowd the Lions could draw for a game was a relatively paltry 15,000. Desperate for a marketing trick to get Detroit excited about its fledgling football franchise, Richards hit on the idea of playing a game on Thanksgiving. Since Richards's WJR was one of the bigger radio stations in the country, he had considerable clout with his network and convinced NBC to broadcast a Thanksgiving game on 94 stations nationwide.

The move worked brilliantly. The undefeated Chicago Bears rolled into town as defending NFL champions, and since the Lions had only one loss, the winner of the first Thanksgiving game would take the NFL's Western Division. The Lions not only sold out their 26,000-seat stadium, they also had to turn fans away at the gate. Even though the juggernaut Bears won that game, the tradition took hold, and the Lions have been playing on Thanksgiving ever since.

This year, the Lions host the Minnesota Vikings.


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The Cowboys, too, jumped on the opportunity to play on Thanksgiving as an extra little bump for their popularity. When the chance to take the field on Thanksgiving arose in 1966, it might not have been a huge benefit for the Cowboys. Sure, the Lions had filled their stadium for their Thanksgiving games, but that was no assurance that Texans would warm to holiday football so quickly.

Cowboys general manager Tex Schramm, though, was something of a marketing genius; among his other achievements was the creation of the Dallas Cowboys Cheerleaders.

Schramm saw the Thanksgiving Day game as a great way to get the team some national publicity even as it struggled under young head coach Tom Landry. Schramm signed the Cowboys up for the game even though the NFL was worried that the fans might just not show up—the league guaranteed the team a certain gate revenue in case nobody bought tickets. But the fans showed up in droves, and the team broke its attendance record as 80,259 crammed into the Cotton Bowl. The Cowboys beat the Cleveland Browns 26-14 that day, and a second Thanksgiving pigskin tradition caught hold. Since 1966, the Cowboys have missed having Thanksgiving games only twice.

Dallas will take on the Los Angeles Chargers on Thursday.


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In 2006, because 6-plus hours of holiday football was not sufficient, the NFL added a third game to the Thanksgiving lineup. This game is not assigned to a specific franchise—this year, the Washington Redskins will welcome the New York Giants.

Re-running this 2008 article a few days before the games is our Thanksgiving tradition.


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