Category Archives: Life Science

Giant Star Fish and More in Antarctica

photo of giant starfish

Photo by John Mitchell, New Zealand’s National Institute of Water and Atmospheric Research. Read a great deal about the New Zealand Census of Antarctic Marine Life project: 26 scientists and 18 crew took a 50-day voyage aboard RV Tangaroa in February-March 2008.

Benthic invertebrates in Antarctica are well known for their large size. This feature, known as “gigantism” is common amongst certain groups including sea spiders, sponges, isopods, starfish, and amphipods. The phenomenon is a subject of intense scientific investigation, but there are many contributing factors.

Slow growth rates, late reproductive maturation, prolonged periods of embryonic development, and low predation rates that are typical of Antarctic waters contribute to long life-spans for many species and can also result in large size animals. Animal physiology is thought to play a role as well, as those groups that require large amounts of calcium should not, in theory, grow well in Antarctic waters. This is because the calcium carbonate (needed for growth of shells, or starfish ‘tests’) has low solubility in very cold seawater. Yet starfish, which have a calcareous exoskeleton or ‘test’ which needs lots of calcium, can reach much larger sizes than found in New Zealand waters, as seen in [photo].

Another crucial part of the story is that the low sea temperatures allow more oxygen to be dissolved in the sea water than in warmer latitudes. Sea spiders for example are not only larger, but reach more than 1000 times the weight of most temperate species. Amphipod crustaceans in the Southern Ocean are also large; more than five times as long as the largest temperate species.

Baby Sand Dollars Clone Themselves When They Sense Danger

Baby sand dollars clone themselves when they sense danger

The odds of growing up aren’t good for baby sand dollars. Smaller than the head of a pin, the larvae drift in the ocean — easy prey for anything with a mouth.

But a University of Washington graduate student has discovered the tiny animal has a surprising survival strategy: Faced with the threat of being gobbled up, it makes like Dr. Evil from the Austin Powers movies and clones itself. The resulting “mini-me” may escape hungry fish because it is even teenier than the original — and harder to see.

“If you are eaten, but the smaller version of you survives, you’re still a winner from an evolutionary standpoint,” said Dawn Vaughn.
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Familiar inhabitants of Washington’s subtidal zone, sand dollars start life though the chance encounter of sperm and egg, simultaneously released into the water by mature adults. The larvae free-float for about six weeks before metamorphosing into miniature sand dollars that settle in colonies and eventually grow to full size.
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The white shells that wash up on the beach are the creatures’ external skeletons. Living sand dollars are covered with velvety, purple spines used to grab food particles. Vaughn knew many other marine invertebrates shift their shape to avoid being eaten. Colonial animals called bryozoans grow spikes when voracious sea slugs crawl across them. Barnacles take on a bent posture to repel snails. Vaughn’s own previous research showed periwinkle larvae narrow their shell openings to keep out marauding crab larvae.

Chinook Salmon Vanish Without a Trace

The Chinook salmon that swim upstream to spawn in the fall, the most robust run in the Sacramento River, have disappeared. The almost complete collapse of the richest and most dependable source of Chinook salmon south of Alaska left gloomy fisheries experts struggling for reliable explanations – and coming up dry.

Whatever the cause, there was widespread agreement among those attending a five-day meeting of the Pacific Fisheries Management Council here last week that the regional $150 million fishery, which usually opens for the four-month season on May 1, is almost certain to remain closed this year from northern Oregon to the Mexican border.
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So what happened? As Dave Bitts, a fisherman based in Eureka in Northern California, sees it, the variables are simple. “To survive, there are two things a salmon needs,” he said. “To eat. And not to be eaten.”

Fragmentary evidence about salmon mortality in the Sacramento River in recent years, as well as more robust but still inconclusive data about ocean conditions in 2005, indicates that the fall Chinook smolts, or baby fish, of 2005 may have lost out on both counts. But biologists, fishermen and fishery managers all emphasize that no one yet knows anything for sure.

Bird Brain Language Research

Molecular Mapping of Movement-Associated Areas in the Avian Brain: A Motor Theory for Vocal Learning Origin

Vocal learning is a critical behavioral substrate for spoken human language. It is a rare trait found in three distantly related groups of birds-songbirds, hummingbirds, and parrots. These avian groups have remarkably similar systems of cerebral vocal nuclei for the control of learned vocalizations that are not found in their more closely related vocal non-learning relatives. These findings led to the hypothesis that brain pathways for vocal learning in different groups evolved independently from a common ancestor but under pre-existing constraints. Here, we suggest one constraint, a pre-existing system for movement control.

Using behavioral molecular mapping, we discovered that in songbirds, parrots, and hummingbirds, all cerebral vocal learning nuclei are adjacent to discrete brain areas active during limb and body movements. Similar to the relationships between vocal nuclei activation and singing, activation in the adjacent areas correlated with the amount of movement performed and was independent of auditory and visual input.
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Based upon these findings, we propose a motor theory for the origin of vocal learning, this being that the brain areas specialized for vocal learning in vocal learners evolved as a specialization of a pre-existing motor pathway that controls movement.

Secret Life of Microbes

New Window Opens on the Secret Life of Microbes: Scientists Develop First Microbial Profiles of Ecosystems

Nowhere is the principle of “strength in numbers” more apparent than in the collective power of microbes: despite their simplicity, these one-cell organisms–which number about 5 million trillion trillion strong (no, that is not a typo) on Earth–affect virtually every ecological process, from the decay of organic material to the production of oxygen.

But even though microbes essentially rule the Earth, scientists have never before been able to conduct comprehensive studies of microbes and their interactions with one another in their natural habitats.
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Because microbes are an ecosystem’s first-responders, by monitoring changes in an ecosystem’s microbial capabilities, scientists can detect ecological responses to stresses earlier than would otherwise be possible–even before such responses might be visibly apparent in plants or animals, Rohwer said.

Evidence that viruses–which are known to be ten times more abundant than even microbes–serve as gene banks for ecosystems. This evidence includes observations that viruses in the nine ecosystems carried large loads of DNA without using such DNA themselves. Rohwer believes that the viruses probably transfer such excess DNA to bacteria during infections, and thereby pass on “new genetic tricks” to their microbial hosts. The study also indicates that by transporting the DNA to new locations, viruses may serve as important agents in the evolution of microbes.

Dolphin Rescues Beached Whales

New Zealand dolphin rescues beached whales:

The pygmy sperm whales had repeatedly beached, and both they and the humans were tired and set to give up, he said. But then the dolphin appeared, communicated with the whales, and led them to safety.

The bottlenose dolphin, called Moko by local residents, is well known for playing with swimmers off Mahia beach on the east coast of the North Island.
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Mr Smith said he felt fortunate to have witnessed the extraordinary event, and was delighted for the whales, as in the past he has had to put down animals which have become beached. He said that the whales have not been seen since, but that the dolphin had returned to its usual practice of playing with swimmers in the bay.

“I shouldn’t do this I know, we are meant to remain scientific,” Mr Smith said, “but I actually went into the water with the dolphin and gave it a pat afterwards because she really did save the day.”

Dino-Era Feathers Found Encased in Amber

Seven dino-era feathers found perfectly preserved in amber in western France highlight a crucial stage in feather evolution, scientists report. The hundred-million-year-old plumage has features of both feather-like fibers found with some two-legged dinosaurs known as theropods and of modern bird feathers, the researchers said.
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The find provides a clear example “of the passage between primitive filamentous down and a modern feather,” said team member Didier NÃ©raudeau of the University of Rennes in France. The study team isn’t sure yet whether the feathers belonged to a dino or a bird. But fossil teeth from two dino families thought to have been feathered were excavated from rocks just above the layer that contained the amber, Perrichot said. “It is entirely plausible that the feathers come from a dinosaur rather than from a bird,” he said.

Deep-Sea Denizen Inspires New Polymers

Stealing a trick from a tiny, pickle-shaped creature that dwells in the depths of the ocean, scientists have designed a new polymer that, when exposed to water, can instantly change its rigidity and strength.
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Christoph Weder, an associate professor in the same department at Case, says he and Rowan thought of copying the sea cucumber’s adaptation more than five years ago. Working with marine biologists, they determined that the deep-sea animal accomplished its transformation thanks to fibers made of a protein known as collagen. The tightness of the connections between those fibers determines how stiff the cucumber’s skin is, and is controlled by the animal’s nervous system.

To get their polymer to do the same thing, the Case scientists used fibers found in another deep sea dweller, sea squirts, and also in cotton. When they mixed those fibers – known as cellulose nanofibers – with the rubbery polymer ethylene oxide–epichlorohydrin, they formed a stiff network, “almost glued to each other,” says Weder. Due to the nature of the bonds between the polymer and the fibers, however, water gets between the two substances, weakening the fibers’ adhesion. The material then becomes soft.

Vaccine For Strep Infections

Engineered Protein Shows Potential as a Strep Vaccine

A University of California, San Diego-led research team has demonstrated that immunization with a stabilized version of a protein found on Streptococcus bacteria can provide protection against Strep infections, which afflict more than 600 million people each year and kill 400,000.
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Group A Streptococcus (GAS). GAS causes a wide variety of human diseases including strep throat, rheumatic fever, and the life-threatening “flesh-eating” syndrome called necrotizing fasciitis. Studies were performed using M1 protein, which represents the version of M protein present on the most common disease-associated GAS strains.
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“We created a modified version of M1 with a more stable structure, and found that it is just as effective at eliciting an immune reaction, but safer than the original version of M1, which has serious drawbacks to its use in a vaccine.”

Antarctic Fish “Hibernate” in Winter

This is the first time fish have been seen actively becoming torpid—a state similar to hibernation in land animals—as part of an annual cycle. “A lot of freshwater fish go [unexpectedly] dormant in winter because a drop in temperature lowers their metabolism,” said study co-author Hamish Campbell, a zoologist at the University of Queensland, Australia.

“By contrast, these Antarctic fish actively reduce their ‘cost of living,'” he said… “The fish became 20 times less active in winter compared to summer,”… About every week or so the cod wake up and swim around for a few hours, the team observed. “This is quite similar to ‘denning’ in bears, where the hibernation isn’t so deep and the animals can be disturbed, then spend some time awake before going back to bed,” Fraser said.

Full paper: Hibernation in an Antarctic Fish: On Ice for Winter – Arctic Sharks – Antarctic Robo-sub