Researchers from Brazil's TAMAR Project, a sea turtle conservation group, found the dead fish floating near the surface off the Bahia Coast. Although the researchers initially believed they had discovered an entirely new species off fish, ichthyologists believe this odd creature belongs to the Jellynose family of fishes, although no Jellynose has ever been spotted near Brazil. Because of their limited muscle mass, the bodies of the Jellynose are largely gelatinous, and can grow to about six feet in length and up to 100 pounds.

Bizarre Gelatinous Fish Found in Brazil [National Geographic]

Kamal Youcef-Toumi and Pablo Valdivia Y Alvarado, mechanical engineers at MIT, have developed a foot-long mechanical fish that uses a single motor and fewer than ten individual components to move its compliant body. It isn't quite as fast a swimmer as a biological fish, but it's a vast improvement over the four foot long Robotuna MIT engineers debuted in 1994, which had 2,843 parts and six motors.

The robotic fish's similarity to biological fish make it an ideal underwater explorer, able to travel where other underwater vehicles cannot and tend to last longer than their submersible robotic brethren. The engineers' hope is that one day schools of robotic fish can be used to explore submerged structures, patrol lakes and harbors, and monitor large bodies of water for pollutants.

[MIT via Inhabitat]

The team used two different dyes: one absorbs UV light emits blue visible light, and the other absorbs part of the blue light to emit the desired color of light. The proportions of the two dyes can be altered to create an efficient, easily color-tunable light. The LEDs can be tuned to emit either warmer or colder white lights.

The use of DNA as the base polymer also has its purposes. DNA is a very strong polymer, lasting 50 times longer than acrylic. The DNA fibers also orient the dye molecules in the best way possible to make the energy transfer happen.

The process seems a bit overly involved for the result. The scientists have to extract fish DNA, then spin it into nano-fibers, and then coat a UV LED with the fibers. But then again, how many other technologies can claim that their efficiency comes from fish DNA?

Making Light Bulbs from DNA [via Technology Review]

(Image: from Angewandte Chemie.)

This photograph was taken by diver/photographer Paul Nicklen for National Geographic. In a related video, he recounts exactly how the 8-foot-long sailfish work together to drive this roving ball of fish to the slaughter, injuring them with their sword noses, until they are exhausted and the gang of sailfish can move in for the feast. Of the photo above, he says:

More than a hundred sailfish keep tabs on an elephant-size school of sardines off Mexico's Isla Mujeres. The big fish, which can stretch eight feet tip to tip, drive their prey up from deeper water for easier feeding near the sunlit surface.

via National Geographic and Marilyn Terrell

[NMT's AutoFish, via Vision Systems Design]

A study in 2005 at Stanford showed that there is only one gene that controls whether a sticklefish will develop bony plates on its body. So clearly this gene got switched on after the lake was cleaned up. But why? According to PhysOrg:

Back when the lake was polluted, the transparency of its water was low, affording a range of vision only about 30 inches deep. The tainted, mucky water provided the sticklebacks with an opaque blanket of security against predators such as cutthroat trout, and so the fish needed little bony armor to keep them from being eaten by the trout.

In 1968, after the cleanup was complete, the lake's transparency reached a depth of 10 feet. Today, the water's clarity approaches 25 feet. Lacking the cover of darkness they once enjoyed, over the past 40 years about half of Lake Washington sticklebacks have evolved to become fully armored, with bony plates protecting their bodies from head to tail. For example, in the late '60s, only 6 percent of sticklebacks in Lake Washington were completely plated. Today, 49 percent are fully plated and 35 percent are partially plated, with about half of their bodies shielded in bony armor. This rapid, dramatic adaptation is actually an example of evolution in reverse, because the normal evolutionary tendency for freshwater sticklebacks runs toward less armor plating, not more.

"We propose that the most likely cause of this reverse evolution in the sticklebacks is from the higher levels of trout predation after the sudden increase in water transparency," said Peichel, whose Hutchinson Center lab has established the stickleback as a new model for studying complex genetic traits. By examining multifaceted traits in the fish, such as body type and behavior, Peichel and colleagues shed light on the genetic networks at play in other complex traits, such as cancer and other common human diseases.

The ability of the fish to quickly adapt to environmental changes such as increased predation by the cutthroat trout is due, Peichel believes, to their rich genetic variation. The sticklebacks in Lake Washington contain DNA from both marine (saltwater) fish, which tend to be fully plated, and freshwater sticklebacks, which tend to be low-plated. When environmental pressures called for increased plating, some of the fish had copies of genes that controlled for both low and full plating, and so natural selection favored the latter.

"Having a lot of genetic variation in the population means that if the environment changes, there may be some gene variant that does better in that new environment than in the previous one, and so nature selects for it. Genetic variation increases the chance of overall survival of the species," she said.

Researchers document rapid reverse-evolution [PhysOrg]