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Friday Harbor, WA, United States

Crawled News Article
Site: http://phys.org/biology-news/

The ocean predators use their buzz saw mouths to efficiently dismantle prey, ranging from marine mammals and sea turtles to seabirds and—as Hollywood likes to remind us—an occasional human. There are more than 400 species of sharks in the world and each has a unique tooth shape. Some are simple triangles, while others are deeply notched or spear-shaped. But despite this variety, scientists haven't detected a difference in how different shark teeth cut and poke tissue. A recent University of Washington study sought to understand why shark teeth are shaped differently and what biological advantages various shapes have by testing their performance under realistic conditions. The results appeared in August in the journal Royal Society Open Science. "When you have all these different tooth shapes, there should be some functional reason. That issue was fundamentally troubling to me," said senior author Adam Summers, a UW professor of biology and of aquatic and fishery sciences. "It seemed likely what we were missing is that sharks move when they eat." Sharks shake their heads rapidly when they bite their prey, so evaluating how teeth perform while in a side-to-side motion was critical to the study tests, which took place during a summer marine biology course at the UW's Friday Harbor Laboratories on San Juan Island. Summers and his collaborators affixed three different types of shark teeth to the blade of a reciprocating power saw, then cut through thick slices of Alaska chum salmon at a speed that mimicked the velocity of head-shaking as a shark devours its prey. "Sure enough, when we cut through salmon, different teeth cut differently," Summers said. "We found a way to distinguish between this huge morphological difference we see among shark teeth in nature." The researchers also noticed that some species' teeth dulled more quickly than others. Two kinds of teeth, belonging to tiger and silky sharks, dulled after only several passes of the saw blade over tissue, meaning that it's possible these sharks in the wild must replace their teeth every time they kill prey. Teeth from the bluntnose sixgill shark didn't cut as well, but they also didn't dull as quickly as the other teeth. "There's this tradeoff between sharpness and longevity of the tooth edge," Summers explained. "It looks like some sharks must replace their teeth more often, giving them a consistently sharp tool." This might shed light on the feeding patterns of different sharks, the authors explain. For example, bluntnose sixgill sharks with duller, longer-lasting teeth might be swallowing their prey whole. Tiger sharks that eat a larger range of prey such as sea turtles, dugongs and seabirds usually bite their prey to pieces before eating it and would need sharper teeth to puncture a sea turtle's rigid shell, for example. When tissue is punctured and twisted side-to-side as prey is during a shark attack, the prey's tissue doesn't always behave the same way. This is not unlike a child's Silly Putty that will stretch into a long, stringy piece when slowly pulled apart, but break in two when yanked at a much faster speed. Biological tissues behave in the same unpredictable way when pulled, prodded or strained. It was this nuance that the research team tried to capture using experiments that involved movement. They believe it's the first study of its kind for mimicking how sharks hunt and kill. "It is really important to test biological materials at strain rates that are high enough to mimic how the predator and prey tissues would actually behave in real life," said co-author Stacy Farina, a postdoctoral researcher at Harvard University and an adjunct lecturer at Shoals Marine Laboratory. Farina was a teaching fellow at Friday Harbor Labs when the research was conducted. The experiments for this study were designed and carried out during an intensive five-week course at Friday Harbor Labs in summer 2014. Katherine Corn, now at the University of California, Davis, used epoxy from a local hardware store to glue shark teeth to the reciprocating saw blades. The materials worked surprisingly well. "We asked ourselves, how do we safely and effectively move these teeth back and forth quickly? The quick and dirty way was, glue them onto a power saw," Farina said. "It was a simple solution to a complicated problem." A video of the cutting apparatus. A blade with teeth from the bluntnose sixgill shark (Hexanchus griseus) on its fifteenth use. Explore further: Taking the bite out of shark DNA More information: Katherine A. Corn et al, Modelling tooth–prey interactions in sharks: the importance of dynamic testing, Royal Society Open Science (2016). DOI: 10.1098/rsos.160141

Crawled News Article
Site: http://phys.org/biology-news/

New species of deep-water algae was photographed by a SCUBA diver at 200 feet at Kure Atoll in Papahanaumokuakea Marine National Monument. Credit: Daniel Wagner/NOAA Scientists working with NOAA's Office of National Marine Sanctuaries announced the discovery of four new species of deep-water algae from Hawaii. Marine algae, or limu, are very important in Hawaiian culture, used in foods, ceremonies and as adornments in traditional hula. The new species of limu were collected between 200-400 feet, depths not typically known for marine algae. Heather Spalding, Ph.D., postdoctoral researcher at the University of Hawaii Department of Botany and lead author of the study, said, "I was astounded at the abundance and size of these algae, which resembled something you would see in a shallow-water lagoon, not at 400 feet." Spalding has been collaborating with NOAA's Office of National Marine Sanctuaries for several years studying samples collected by NOAA divers working in Papahanaumokuakea Marine National Monument. She and her colleagues at the University of Hawaii and University of Washington's Friday Harbor Laboratories conducted DNA analyses that showed that the species are very different than those found in Hawaii's shallow waters, even though they are very similar in appearance. "If you picked up one of these algae on the beach, you couldn't tell if it was from a nearby rock or washed up from the deep, the species look that similar," Spalding said. The newly discovered species are similar in appearance to limu palahalaha (Ulva lactuca), or sea lettuce. Scientists consulted with the Native Hawaiian community to develop meaningful names for the new species to honor the great importance they have in Hawaiian culture. One species was named Ulva iliohaha, which refers to the foraging behavior of ilioholoikauaua, the endangered Hawaiian monk seal, one of the best-known residents of Papahanaumokuakea. The species were sampled during surveys between 2013 and 2015 in Papahanaumokuakea Marine National Monument by NOAA divers using advanced SCUBA diving technologies, and during past NOAA expeditions from 2006 to 2014 throughout the Main Hawaiian Islands using submersibles operated by the Hawaii Undersea Research Laboratory. Scientists anticipate that many additional new species of algae will be described in the coming years from samples collected by NOAA divers on future expeditions to the monument. "These findings redefine our understanding of algal distributions in Hawaii, and hint at the great number of other new species that are likely to be discovered in the future from these amazing deep-water reefs," said Daniel Wagner, Papahanaumokuakea research specialist with NOAA's Office of National Marine Sanctuaries. More information: Heather L. Spalding et al. New Ulvaceae (Ulvophyceae, Chlorophyta) from mesophotic ecosystems across the Hawaiian Archipelago, Journal of Phycology (2015). DOI: 10.1111/jpy.12375

Strathmann R.R.,Friday Harbor Laboratories | Strathmann M.F.,Friday Harbor Laboratories | Ruiz-Jones G.,Kewalo Marine Laboratory | Hadfield M.G.,Kewalo Marine Laboratory
Invertebrate Biology

Plasticity in hatching can balance risks of benthic and pelagic development and thereby affect the extent of larval dispersal. Veligers of the nudibranch Phestilla sibogae hatched from their individual capsules if the encapsulated embryos were scattered from a torn gelatinous egg ribbon. Hatching occurred as early as day 4 at 23°-25°C. The early hatchlings lacked a propodium, swam, and were not yet competent to settle and metamorphose. Hatching may be induced by predation: crabs consumed egg ribbons, and a portunid crab, caught in the act of tearing an egg ribbon, scattered encapsulated embryos. Undisturbed egg masses hatched as late as 9-11 d at 23°-25°C, or as early as 8 d in a trial at 26°C. Late hatchlings had a well-developed propodium, and 20-100% metamorphosed within a day of exposure to the inducer from the nudibranch's coral prey. A few metamorphosed nudibranchs were found within hatching egg masses. Thus, the veligers can hatch so late that many are competent to metamorphose or so early that the obligate planktonic period can last 4 or more days. An attack by a predator means the benthic habitat is dangerous for the embryos, and swimming is presumably the safer option. the absence of disturbance, the veligers hatch when ready or nearly ready to settle. © 2010, The American Microscopical Society, Inc. Source

Pirtle T.J.,Grand Canyon University | Pirtle T.J.,Friday Harbor Laboratories | Willingham K.,Texas Tech University Health Sciences Center | Willingham K.,Friday Harbor Laboratories | And 2 more authors.
Comparative Biochemistry and Physiology - A Molecular and Integrative Physiology

The pteropod mollusk, Clione limacina, exhibits behaviorally relevant swim speed changes that occur within the context of the animal's ecology. Modulation of C. limacina swimming speed involves changes that occur at the network and cellular levels. Intracellular recordings from interneurons of the swim central pattern generator show the presence of a sag potential that is indicative of the hyperpolarization-activated inward current (Ih). Here we provide evidence that Ih in primary swim interneurons plays a role in C. limacina swimming speed control and may be a modulatory target. Recordings from central pattern generator swim interneurons show that hyperpolarizing current injection produces a sag potential that lasts for the duration of the hyperpolarization, a characteristic of cells possessing Ih. Following the hyperpolarizing current injection, swim interneurons also exhibit postinhibitory rebound (PIR). Serotonin enhances the sag potential of C. limacina swim interneurons while the Ih blocker, ZD7288, reduces the sag potential. Furthermore, a negative correlation was found between the amplitude of the sag potential and latency to PIR. Because latency to PIR was previously shown to influence swimming speed, we hypothesize that Ih has an effect on swimming speed. The Ih blocker, ZD7288, suppresses swimming in C. limacina and inhibits serotonin-induced acceleration, evidence that supports our hypothesis. © 2010 Elsevier Inc. Source

Nishizaki M.T.,University of Washington | Nishizaki M.T.,Friday Harbor Laboratories | Carrington E.,University of Washington | Carrington E.,Friday Harbor Laboratories
Journal of Thermal Biology

Organisms employ a wide array of physiological and behavioral responses in an effort to endure stressful environmental conditions. For many marine invertebrates, physiological and/or behavioral performance is dependent on physical conditions in the fluid environment. Although factors such as water temperature and velocity can elicit changes in respiration and feeding, the manner in which these processes integrate to shape growth remains unclear. In a growth experiment, juvenile barnacles (Balanus glandula) were raised in dockside, once-through flow chambers at water velocities of 2 versus 19cms-1 and temperatures of 11.5 versus 14°C. Over 37 days, growth rates (i.e., shell basal area) increased with faster water velocities and higher temperatures. Barnacles at high flows had shorter feeding appendages (i.e., cirri), suggesting that growth patterns are unlikely related to plastic responses in cirral length. A separate experiment in the field confirmed patterns of temperature- and flow-dependent growth over 41 days. Outplanted juvenile barnacles exposed to the faster water velocities (32±1 and 34±1cms-1; mean±SE) and warm temperatures (16.81±0.05°C) experienced higher growth compared to individuals at low velocities (1±1cms-1) and temperatures (13.67±0.02°C). Growth data were consistent with estimates from a simple energy budget model based on previously measured feeding and respiration response curves that predicted peak growth at moderate temperatures (15°C) and velocities (20-30cms-1). Low growth is expected at both low and high velocities due to lower encounter rates with suspended food particles and lower capture efficiencies respectively. At high temperatures, growth is likely limited by high metabolic costs, whereas slow growth at low temperatures may be a consequence of low oxygen availability and/or slow cirral beating and low feeding rates. Moreover, these results advocate for approaches that consider the combined effects of multiple stressors and suggest that both increases and decreases in temperature or flow impact barnacle growth, but through different physiological and behavioral mechanisms. © 2015 Elsevier Ltd. Source

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