When Injured, the Moon Jellyfish Doesn’t Repair. It Recycles!

moon jellyfish

Moon jellyfish possess a unique mechanism for self-repair. (Photo credit: Byba Sepit/Moment/Getty Images)

The moon jellyfish is a tough creature to figure out. For one, while experts argue that the species consists of numerous subspecies, it is nearly impossible to distinguish one from another without DNA testing, which leads other scientists to propose the distinction is meaningless. [Read more…]

Pyrosomes: The Ultimate Social Networkers

pyrosome

This pyrosome is made up of thousands of tiny organisms linked together as one. (Photo credit: Mark Conlin/Alamy)

If you’re looking for a strange sea creature, you can’t get much weirder than the giant pyrosome. With an appearance like a monster out of a science fiction movie, those who’ve had the good luck to see them have likened them to everything from unicorns, due to their rareness, to the Borg, because of how they stick together and seem to be part of a collective.

[Read more…]

Pyrosomes: The Ultimate Social Networkers

pyrosome

This pyrosome is made up of thousands of tiny organisms linked together as one. (Photo credit: Mark Conlin/Alamy)

If you’re looking for a strange sea creature, you cant get much weirder than the giant pyrosome. With an appearance like a monster out of a science fiction movie, those who’ve had the good luck to see them have likened them to everything from unicorns, due to their rareness, to the Borg, because of how they stick together and seem to be part of a collective.

[Read more…]

The Glowing Ocean

glowing dinoflagellates

Dinoflagellates makes these ocean waters glow. (Photo credit: ArtTomCat/Shutterstock)

Whether seen from the beach or from the seat of a kayak, the glowing ocean is a phenomenon that, once experienced, is not soon forgotten. What causes this strange glow in the oceans water? And what purpose if any does it serve? [Read more…]

Sponges Descended from Unique Ancestor

Researchers have discovered that sponges evolved from a separate ancestor than all other animals. This finding is contrary to popular thought that places a sponge-like creature as the ancient ancestor of all other animals.

Research indicates that sponges evolved from a separate ancestor than all other animals. (Photo credit:  Andrew David, NOAA/NMFS/SEFSC Panama City; Lance Horn, UNCW/NURC - Phantom II ROV operator.)

Research indicates that sponges evolved from a separate ancestor than all other animals. (Photo credit: Andrew David, NOAA/NMFS/SEFSC Panama City; Lance Horn, UNCW/NURC – Phantom II ROV operator.)

The three main researchers associated with this study include Herv Philippe of the Universit de Montral in Montreal, Canada, Gert Wrheide of the Ludwig-Maximillians Universistt in Munich, Germany; and Michael Manuel of the University of Paris in Paris, France. In their research, the scientists studied 128 genes from 55 different species. These species included 9 poriferans, 8 cnidarians, 3 ctenophores, and 1 placozoan. The scientists used a technique called phylogenomics. This technique uses computers to analyze and compare large datasets of gene sequences to determine evolutionary relationships. By determining evolutionary relationships, the scientists were able to develop a phylogenetic tree to show how related each animal was to another. In studying these relationships, the scientists found that poriferans developed from a separate ancestor than the other groups of animals. They also found evidence that cnidiarians and ctenophores belong to a common group.

Future research plans include determining when specific features evolved in animals. The scientists are especially interested in determining how the “genetic toolkit” necessary for the development of animal nervous systems, muscles, and sensory organs evolved.

The research was published in the April 2, 2009 edition of the journal Current Biology. The study was funded by the Deutsche Forschungsgemeinschaft as a part of the Priority Program 1174 “Deep Metazoan Phylogeny.”

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A Shark That Lives Among the Ice

Scientists are just now beginning to learn more about the elusive Greenland shark. (Photo credit: SeaPics.com)

The word “shark” probably conjures up images of the iconic grey dorsal fin wending its way toward a populated beach like in the movie Jaws. However, not all sharks inhabit coastal or tropical waters. In fact, one shark lives quite far from the nearest beach. This shark is the Greenland shark–and it lives in the polar latitudes of the northern Atlantic Ocean.

Until recently, not much was known about the Greenland shark (Somniosus microcephalus). Though scientists have had some luck with catching and tagging live Greenland sharks, much of the Greenland sharks’ lives still remains a mystery.

The Greenland shark lives in the cold waters of the Arctic and sub-Arctic regions. Here water temperatures range from -2°C to 7°C. The Greenland shark is the only shark found to live in such cold waters. These sharks are found from Baffin Island in northern Canada south to the Gulf of Maine. On rare occasion, these sharks have been found as far south as the Gulf of Mexico. The Greenland shark typically lives in waters below 200 meters in depth. During the summer, the sharks live in depths of 180 to 730 meters. During the winter, the sharks stay closer to the surface.

Natural History

The average size of the Greenland shark ranges from 3.5 to 5 meters. These cartilaginous fish have been known to reach a length of 7 meters (about half the length of a school bus) and a mass of over 1000 kilograms.

Given their icy habitat, it should come as little surprise that Greenland sharks are relatively sluggish creatures. It is thought that the sharks are either ambush predators (that is, they lie in wait for prey to come into reach) or scavengers. Examination of the shark’s stomach has shown that the animals eat oceanic and benthic (bottom-dwelling) species of fish, invertebrates, and marine mammals such as seals. On rare occasion, the sharks have been known to eat polar bear, dog, reindeer, and caribou. Anecdotal evidence suggests that Greenland sharks lie in wait as ambush predators for caribou in Canadian and Arctic rivermouths. However, not enough firm evidence has been found to corroborate these anecdotes as normal behavior as of yet.

Most Greenland sharks have parasites that cling to their eyes. (Photo credit: SeaPics.com)

Though scientists have not observed Greenland sharks mating or giving birth to live young, they do know that the sharks typically have a litter size of 10 pups. Shark pups are born at a size of 38 centimeters. Greenland sharks grow at an extremely slow rate–data gathered from tagged adult sharks suggests that they may grow at a rate of just one centimeter per year.

Greenland sharks are known to be parasitized by the copepod Ommatokoita elongata. The copepod attaches itself to and feeds on the cornea of the shark’s eye. This attachment damages the shark’s eye and can lead to blindness. However, since the sharks live most of their lives at a depth far below the surface of the ocean (and therefore mostly in the dark), losing their sight is not catastrophic. Research indicates that 85 percent of the Arctic population of Greenland sharks are parasitized by this copepod.

Current Research

New technology has greatly aided scientists’ study of Greenland sharks. One important tool researchers are using to track the sharks is “pop-up” satellite archival tags. These tags have sensors that store data every hour on water depth, temperature, and geographical location. After a pre-determined length of time, the tags detach from the shark and “pop-up” to the surface where they transmit the data to orbiting satellites. Scientists are then able to retrieve and analyze the data from the satellites. The data from these tags provide researchers with intimate details about the sharks’ lives without harming the shark in the process.

In addition, researchers with the Greenland Shark and Elasmobranch Education and Research Group have used a submersible VideoRay ROV (remotely operated vehicle) to track Greenland sharks in the low-light conditions of the St. Lawrence waterway. As technologies improve, scientists are able to gather more data about the natural history of the elusive Greenland shark. These data will help to provide more information on the Greenland shark’s day-to-day activities and its place in the Arctic ecosystem as a whole.

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Deep-Sea Fish Uses Unusual Method to See

The brownsnout spookfish Dolichopteryz longipes uses mirrors to focus its eyes. (Photo Credit: David Shale/NPL)

The brownsnout spookfish is found in tropical to temperate waters of the Atlantic, Pacific, and Indian oceans. The spookfish lives in the deep-sea, about 1000 meters beneath the ocean’s surface, where light does not penetrate. Although the existence of this deep-sea fish was discovered 120 years ago, it was not until recently that scientists were able to observe the fish up-close. Prof. Hans-Joachim Wagner of Tbingen University in Germany caught a live specimen off the island of Tonga in the Pacific Ocean. While examining the fish, scientists made an exciting discovery–the spookfish uses mirrors, rather than lenses, to focus its eyes. Flash photography was used to verify that the fish focuses its eyes with the use of mirrors. Dissection studies helped to confirm the scientists’ discovery.

Organisms that live in the deep-sea must have adaptations that let them find food and avoid predators in their low-light habitat. Deep in the ocean, the only light that exists comes from flashes of light given off by bioluminescent organisms. Bioluminescence refers to a light made by a chemical reaction within an organism. Most deep-sea bioluminescent creatures give off a blue shade of light, since that color is most easily transmitted in a marine environment. One example of a bioluminescent animal is the anglerfish. This deep-sea fish has a lighted “lure” attached to its head to attract prey.

Although the spookfish looks like it has four eyes, it actually only has two. Each eye is split into two connected halves. One half of the eye points upward, which gives the fish a view of the ocean above. The bottom half of the eye points downward, into the darkness of the abyss below.

As shown in this photo, the spookfish’s eye is made of two-connected parts. (Photo Credit: Dr. Tamara Frank)

The mirrors in the spookfish’s eyes are made up of tiny plates of guanine crystals, arranged in a stack made up of many layers. The arrangement and orientation of the crystals direct any light that enters the spookfish’s eye into a focus. The mirrors let the spookfish quickly produce bright, high-contrast images, giving it an immediate picture of what is around it. In contrast to mirrors, lenses are less efficient because they do not reflect all the light that hits them, and instead absorb some of the light.

Additional work to corroborate this discovery was conducted by Prof. Julian Partridge of Bristol University in England. Partridge developed a computer simulation that illustrates how the orientation of the plates within the spookfish’s eyes are perfectly adapted for focusing reflected light on the fish’s retina.

The scientists’ findings are reported in the January 27 edition of the journal Current Biology. The article, titled “A Novel Vertebrate Eye Using Both Refractive and Reflective Optics,” was co-authored by Hans-Joachim Wagner, Ron H. Douglas, Tamara M. Frank, Nicholas W. Roberts, and Julian C. Partridge.

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Scientists Begin to Unravel Mystery of Marine Animals’ Migration

Hatchling loggerhead turtles, such as this one, imprint on the magnetic field of their birthplace. (Photo credit: Ken Lohmann, University of North Carolina at Chapel Hill)

Scientists at the University of North Carolina-Chapel Hill are working to unravel the mystery of how (and why) some marine animals return to where they were born to reproduce. For example, some salmon migrate over 1000 miles from the ocean upriver to their spawning grounds. Young loggerhead turtles from the North Atlantic migrate over 9000 miles before returning to the North American coast to reproduce.

Dr. Kenneth Lohmann, a professor of biology in the College of Arts and Sciences, and his team of researchers theorize that marine animals imprint on the magnetic field of the home area where they are born, and use differences in Earth’s magnetic field to return to their birthplace when it comes time to reproduce. Earth’s magnetic field differs across the globe, meaning that different areas of Earth have a different magnetic “fingerprint.” In addition, different regions of the ocean have slightly different magnetic fields, which allows migrating marine animals to home in on their place of birth.

Scientists think that learning more about how and when marine animals imprint on Earth’s magnetic field will help in future conservation projects. For example, scientists might be able to use knowledge of magnetic fields to direct sea turtles to protected areas, or re-establish salmon populations in rivers.

The full results of the scientists’ research are reported in latest edition of Proceedings of the National Academy of Sciences. Lohmann co-authored the paper along with UNC researchers Dr. Catherine Lohmann, a biology lecturer, and Nathan Putman, a graduate student in the biology department. The study was funded by the National Science Foundation.

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Sometimes Even Algae Gets Sunburned

The pale color and white tips of this red algae is the result of too much ultraviolet radiation. (Photo Credit: Max Schwanitz, Alfred Wegener Institute)

The pale color and white tips of this red algae is the result of too much ultraviolet radiation. (Photo Credit: Max Schwanitz, Alfred Wegener Institute)

Plants and photosynthetic algae rely on the Sun as a source of energy to power photosynthesis. Without the Sun, these organisms would not be able to make the energy needed to perform the functions necessary for survive. However, there is such a thing as too much Sun. Similar to the sunburn you may get after sitting in the Sun too long, plants are also susceptible to overdoses of ultraviolet radiation.

When plants receive more light than they can use, light sensitive pigments used to absorb light for photosynthesis may become damaged. Overexposure to light may result in black spots, pale leaves, or rotten parts on the affected plant. Many plants and photosynthetic algae have developed strategies to deal with an excess of ultraviolet radiation.

For example, when a certain species of red algae receives too much ultraviolet radiation, the algae produces fewer red light-collecting proteins so that less radiation is absorbed. Outwardly, the algae turns a paler shade of red and forms white tips. In addition, the algae also produces mycosporin amino acids, a substance similar to melanin in humans. In humans, melanin absorbs ultraviolet radiation, protecting the skin from harm and forming a natural suntan.

However, due to the depletion of the ozone layer, more dangerous short-wavelength ultraviolet radiation is able to penetrate the Earth’s surface and seawater. The mechanisms that plants and photosynthetic algae have to protect themselves from ultraviolet radiation do not work well against these more harmful ultraviolet rays. In algae, the more dangerous ultraviolet radiation harms the organism’s ability to photosynthesize and negatively impacts the organism’s DNA. This damage leads to a much slower rate of growth and reduced reproductive success for the algae. Particularly sensitive are spores and algal gametes, for which even tiny doses of ultraviolet radiation are deleterious.

Researchers associated with the German French Research Base AWIPEV on Spitsbergen (a Norwegian island in the Arctic) have found that the distribution of certain species of algae are inhibited by ultraviolet radiation. They also found that as ultraviolet radiation increases, the algae are displaced into even deeper waters. According to the researchers, continued study of underwater algae is important as it illustrates how marine coastal ecosystems are being impacted by global climate change.

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