Tuesday, December 21, 2010
This study is a great follow-up to yesterday's post on herbal supplements.
-- The herbal remedy echinacea, believed by many to cure colds, is no better than a placebo in relieving the symptoms or shortening the duration of illness, a new study finds.
"My advice is, if you are an adult and believe in echinacea, it's safe and you might get some placebo effect if nothing else," said lead researcher Dr. Bruce Barrett, an associate professor of medicine at the University of Wisconsin. "I wouldn't say the results of the trial should dissuade people who are currently using echinacea and feel that it works for them, but there is no new evidence to suggest that we have found the cure for the common cold."
If echinacea was able to significantly reduce the symptoms and length of colds, this study would have found it, Barrett noted. "With this particular dose of this particular formulation of echinacea there was no large benefit," he said.
The report is published in the Dec. 21 issue of the Annals of Internal Medicine.
Source:MONDAY, Dec. 20 (HealthDay News)
Monday, December 20, 2010
Plants have been used as medicines since the beginning of time. Today anyone can go into a store and purchase herbal supplements that are advertised to help with everything from depression to weight loss.
People in the United States spent more than $5 billion on herbal and botanical dietary supplements in 2009, up 22% from a decade before, according to the American Botanical Council, a nonprofit research and education organization.
The increase has prompted some concern from doctors and health researchers. There are worries regarding the purity and consistency of supplements, which are not regulated as strictly as pharmaceutical drugs.
Some products contain less than the promoted amount of the supplement in question — such as a 400-milligram capsule of echinacea containing just 250 milligrams of the herb. Other products are tainted by pesticides or heavy metals.
But even when someone takes a valid herbal supplement, it may not be as effective when taken as a pill or capsule rather than used in the traditional manner. For example, an herb normally ground into paste as part of a ceremony might lose its effectiveness if prepared using modern manufacturing methods.
Researchers also are concerned that there just isn't a lot of evidence to support the health benefits said to be gained from herbal supplements. People may be misusing them, which can lead to poor health and potential interactions with prescription drugs.
However, there are two sides to this discussion. Many people have found herbals to be an effective treatment for things that physicians were unable to diagnose and treat.
Source:Dennis Thompson HealthDay/USA Today12/17/10
Tuesday, December 14, 2010
This information comes form Dr. David Wolf, an optometric physician:
Eyelid twitches can be annoying, but they usually go away in a few days. Many things can contribute to eyelid twitching, including:
• Bright lights
• Dry eyes
• Eye infection
• Eye inflammation
• Prolonged computer use
• Sleep deprivation
To help prevent or alleviate eye twitches:
• Avoid or limit caffeine, not just in coffee or tea, but in chocolate, pain relievers, diet pills, and cold medicine as well.
• Get plenty of sleep.
• Limit the time you spend in bright light.
• Practice stress management techniques, such as deep breathing, soaking in a hot tub, listening to soothing music, or exercising most days.
• Take plenty of breaks when you work on a computer.
• Use a rewetting eye drop.
• Wear UV-protective sunglasses.
People often ask me, "Why should I care if a species goes extinct? It's not essential to my daily life, is it?"
Well, according to new research published December 2 in Nature, the answer is yes—healthy biodiversity is essential to human health. As species disappear, infectious diseases rise in humans and throughout the animal kingdom, so extinctions directly affect our health and chances for survival as a species.
"Biodiversity loss tends to increase pathogen transmission across a wide range of infectious disease systems," the study's first author, Bard College ecologist Felicia Keesing, said in a prepared statement.
These pathogens can include viruses, bacteria and fungi. And humans are not the only ones at risk: all manner of other animal and plant species could be affected.
The rise in diseases and other pathogens seems to occur when so-called "buffer" species disappear. Co-author Richard Ostfeld of the Cary Institute of Ecosystem Studies points to the growing number of cases of Lyme disease in humans as an example of how this happens. Opossum populations in the U.S. are down due to the fragmentation of their forest habitats. The marsupials make poor hosts for the pathogen that causes Lyme disease; they can also better defend themselves from the black-legged ticks that carry the affliction to humans than can white-footed mice, which, on the other hand, are thriving in the altered habitat—and along with them disease-carrying ticks. "The mice increase numbers of both the black-legged tick vector and the pathogen that causes Lyme disease," Ostfeld said.
The authors focused on diseases—including Lyme, West Nile virus, hantavirus and nine others—around the world. In each case they found that the maladies have become more prevalent during the time in which local biodiversity shrank.
Three of the cases they studied found that the rise of West Nile virus in the U.S. corresponded to decreases in bird population density.
The researchers also conclude that humans and wildlife really shouldn't interact. Direct contact with wildlife—say, in the form of the often illegal bushmeat trade—could in turn cause more diseases to jump from animals to humans.
The best solution to both situations: "Preserving large intact areas and minimizing contact with wildlife would go a big step of the way to reducing disease," Keesing said in Nature.
So should you care? Yes you should, if you value your health. A healthy planet equals healthy humans, a lesson it's really time we learned.
Source: Scientific American 12/7/2010
Wednesday, December 8, 2010
In a study published in the journal Human Psychopharmacology: Clinical and Experimental, researchers at the University of Barcelona discovered that the caffeine-glucose combo boosts your brain in terms of attention and memory. And here we thought that stuff was bad for us. D’oh!
Researchers tapped 72 men and women, ages 18 to 25, for their caffeine/glucose experiments which, sadly, involved neither Starbucks nor Krispy Kreme donuts. After fasting overnight, subjects received doses of water, water plus caffeine, water plus glucose, or water plus caffeine and glucose (about the same amount you’d get in two soft drinks). Then they were tested on attention, manual dexterity, visuo-spatial and frontal functions and memory via a battery of tests such as remembering a list of 15 repeated words; taking a peg from a cup and quickly inserting it into a hole; sorting cards imprinted with shapes, numbers or colors; and repeating a series of numbers forward and backward. In other words, standard staff meeting stuff.
As it turned out, the subjects’ reaction time improved in water spiked with either caffeine or glucose (glucose gave a bump to their manual dexterity, as well). But a combination of caffeine and glucose showed beneficial effects on attention and on learning and consolidation of verbal memory,; in other words, the coffee-sugar combination boosted the effects of both substances, making the test subjects’ brains more efficient.
As usual, researchers say further studies are needed, particularly with regard to investigating the “effects of caffeine and glucose, alone and in combination, with repeated doses.”
Friday, December 3, 2010
The power of "Power Bracelets" appear dubious from a science perspective. The kinesiology behind the magnetic resonance and the frequency of emissions is not well explained. It appears that this bracelet may be a placebo - meaning the power is more in the mind than in the muscle.
Well, hopefully not my biology class :)
Seriously,our eyes are a portal to our emotions and feelings. When we are happy our eyes seem to sparkle, when we smile we smile not only with our mouth but our eyes light up too. The glaze you are talking about usually occurs when mentally you have "checked out" of a conversation. Your mind has wondered into another place, thus the vacant look in your eyes.
The only other scientific explanation I could find on this related to blood supply but I don't think that really applies to the context of your question.
It appears that the key to understanding aging is to look at it from a genetic perspective. At the end of all chromosomes are stretches of protein called telomeres. These telomeres protect the chromosome but every time the chromosome replicates (like in cell division), the telemeres shorten until the cell can no longer divide.
These shortened telomeres also appear to be the cause of some cancers. Studies have found shortened telomeres in pancreatic, bone, prostate, bladder, lung, kidney, and head and neck cancer.
Research looks promising in using an enzyme, telomerase,in allowing cells to divide beyond their usual life span.
Thursday, November 18, 2010
Fish swimming together is a great example of "safety in numbers". In a school, the fish in the middle of the group are well protected from predators and the abundance of the fish in one area may confuse actually confuse the predator making them less efficient on hunting.
There is one downside to being in the middle of the pack - lack of oxygen. Scientists have found that fish swimming in the middle of a school have access to 25% less oxygen than the fish swimming on the periphery. This causes the school to change shape frequently as fish move from the inside to the outside of the formation.
Most researchers and physicians feel that ADHD is genetically determined. Looking for a link to this disease and food has been going on for over 35 years yet no definitive information has been discovered.
"Scientific evidence is limited to support the association between food additives and ADHD symptoms," says Dr. Maida Galvez, M.D., director of the pediatric environmental health specialty unit at Mount Sinai School of Medicine, in New York City. "Although it is possible that a very small group of children who are allergic to artificial colorings or preservatives may show improvement in symptoms on restriction diets, evidence is insufficient to recommend routine, widespread use of restriction diets to treat a child's ADHD symptoms."
What makes this even more difficult to study is that most foods contain multiple dyes so knowing exactly which one might cause an increase in hyperactivity is tricky.
Wednesday, November 17, 2010
Hiccups can be caused by laughing, sneezing or coughing so it probably is possible to cause yourself to have hiccups. Hiccups are usually harmless but can cause discomfort in the diaphragm when they go on for a period of time.
Sleepwalking happens most frequently in children aged 4-8 years and it appears to run in families. Doctors aren't sure exactly what causes someone to sleep walk but it may be related to fatigue or anxiety.
The episode of sleepwalking can last from less than a minute to 30 minutes. Usually the sleep walker goes back to sleep but may not return to their bed meaning that they wake up in a different place.
Sleepwalking usually decreases as a child gets older.
Source: National Institute of Health
Monday, November 15, 2010
Multiple births are very interesting. Triplets, if they come from the same egg that divides after fertilization, all have identical DNA. Identical triplets are very rare.
There are two other ways that triplets can occur. Non-identical triplets occur when three eggs are produced and each is fertilized separately, these triplets do not have the same DNA. The second way is for one egg to be fertilized and then divides creating two identical twins with the same DNA and then a second egg is fertilized. In this last example, two babies have the same DNA and third one is close but not identical.
Friday, November 12, 2010
Tuesday, November 9, 2010
Lots of things can cause someone to love one food and hate another. It could be the texture of the food, the smell or look of the food, or a cultural preference for a food because it reminds you of family traditions.
Scientists have found that people have a preference for creamy sensations as well as for foods that start off solid and melt in the mouth such as ice cream and chocolate.
Another factor in food preferences: People vary—probably based on genetics—in their ability to detect other textures, such as fat, and bitter and sweet tastes. Valerie Duffy, a registered dietitian and professor in the department of allied health science at the University of Connecticut, Storrs, Conn., has shown in her research that adults with a gene that makes bitter tastes more intense consume fewer vegetables containing bitter compounds, such as kale or spinach.
So you can see that taste preferences are really a very complex topic and you would be hard pressed to find a friend who had exactly the same favorite food as you do.
Source: Wall Street Journal 11/8/10
Monday, November 8, 2010
It appears that genes do play a role in how long you sleep.
Geneticists studying sleep duration in people scanned the DNA of more than 4,200 Europeans, looking for genes associated with a person’s average nightly sleep time. The team found that people who have one version of a gene called SUR2 sleep about 28 minutes longer than people who have another version of the gene, said Karla Allebrandt of the University of Munich, who presented the research November 5 at the annual meeting of the American Society of Human Genetics.
Last year researchers from the University of California, San Francisco reported that a rare variation in DEC2, a gene involved in regulating the body’s daily rhythms, is associated with sleeping almost two hours a night less than average.
Source: Science News 9/12/10, p. 11.
Wednesday, November 3, 2010
I know you about BPA before in water bottles but I just heard that it is in foods too - is that right?
Great and very current question! The newest research on BPA* in foods was done close to home by the University of Texas School of Public Health. They shopped grocery stores in Dallas and then went back to the lab to analyze the foods. Here is what they found: "the Texas contingent locally purchased three samples of each of 31 types of canned or plastic-packaged foods. Another four examples of fresh meat and eight different types of pet food were also collected. All were analyzed for BPA — and 60 percent of the different food products hosted measurable quantities. Ironically, pet food contained less of the pollutant than did most of the items destined for human consumption."
The tested foods weren't just generic, cheap brands but well known foods like Del Monte Fresh Cut Green Beans sporting 26.6 to 65 nanograms of BPA per gram of product; Progresso Light Homestyle Vegetable and Rice Soup with 15.6 to 22.7 ng/g; Campbell’s Condensed Chicken Noodle Soup with 4.46 to 7.05 ng/g; and Chef Boyardee Spaghetti and Meatballs with 4.31 to 5.04 ng/g.of food.
Should we be concerned about this finding? These levels may not be harmful when looked at individually but over time and with use of multiple products the exposure to this chemical may be much higher.
* BPA or Bisphenol A is a chemical that acts as a hormone in the body.
Source: Science News Novemeber 2, 2010
The Maine Potato Lady has this to say about the new and very popular purple potato: "Majestic purple flesh inside satiny purple skin beautifully describes this newly-released variety...All Blue crossed with a white fleshed chipping variety has produced a royal potato exceptionally high in anthocyanins, an antioxidant". The web site is selling these potato plants and has them labeled as organic.
This is a great example where plants that are raised organically are still genetically modified. Many time consumers think that "organic" is another word for healthy and pure and don't realize that their food is genetically manipulated by scientists.
Friday, October 29, 2010
Doctors rely on genetic testing in many conditions, most of them involving pregnant women or infants. However, they may also be used in adults to see if they carry a risk factor for a disease before the symptoms even begin to show up. Doctors use genetic tests for several reasons. These include:
•Finding possible genetic diseases in unborn babies
•Finding out if people carry a gene for a disease and might pass it on to their children
•Screening embryos for disease
•Testing for genetic diseases in adults before they cause symptoms
•Confirming a diagnosis in a person who has disease symptoms
People have many different reasons for being tested or not being tested. For many, it is important to know whether a disease can be prevented or treated if a gene alteration is found. In some cases, there is no treatment. But test results might help a person make life decisions, such as career choice, family planning or insurance coverage.
How do you feel about genetic testing?
Thursday, October 28, 2010
Polygenic traits are traits that are controlled by several different genes. Usually these traits exist on a continuum of expression. For example consider height; there are not just two types of height but instead normal height exists on a fairly large continum of about 12 inches. Where you fall in this height range is caused by genetic material on several different genes. Other examples of the influence of multiple genese can be seen in skin color, autism, hypertension, hair color and eye color.
First let's start with a few definitions.
With incomplete dominance, a cross between organisms with two different phenotypes produces offspring with a third phenotype that is a blending of the parental traits. With codominance, a cross between organisms with two different phenotypes produces offspring with a third phenotype in which both of the parental traits appear together.
Here are a couple of examples: Incomplete dominance is seen in wavy hair. It is a new phenotype that occurs when one parent has straight hair and one parent has curly hair. An example of condominance is found in blood types. The blood type AB is made up of both A proteins and B proteins.
Friday, October 22, 2010
According the the manufacture, Johnson and Johnson, DERMABOND® is an adhesive material which forms a strong microbial shield to protect wounds while they heal.
DERMABOND® wears off naturally during the healing process, which is usually completed within 7 to 10 days. It appears that this material can take the place of stitches.
Hydrogels are also used for wound but their purpose is to provide a moist environment for wound healing. Johnson and Johnson also makes a hydrogel product called Nu-gel.
Thursday, October 21, 2010
Actually, they don't.
Jeffrey Mogil, Ph.D., is professor of pain studies at McGill University in Montreal, Canada. He explains that while not all studies have found sex differences, those which have all point in the same direction that contradicts conventional wisdom. "Females are more sensitive to pain, less tolerant and more able to discriminate different levels of pain than males," he says. This is true in studies of both humans and animals.
Another really interesting finding from Dr. Mogil relates to pain and hair color.He found that natural red heads (female only) experience pain differently from blondes or brunettes. This was not true in males. "It turns out that processing pain involves a receptor which, when mutated, produces red hair and fair skin, among other changes. This receptor—the MC1r receptor— was initially thought to occur only in the skin. However, it has now been found in the brain, and there, in women, it's part of the pathway that processes pain."
Another great question on cancer!
Inheriting cancer in vitro is extremely rare. It appears that only 30 documented cases show the infant received cancer from the mother before birth. There was previously no genetic evidence to explain why a child’s immune system would not recognize and destroy any invasive cancer cells that were of maternal — and therefore, foreign — origin.
The new study, led by Mel Greaves, of the Institute of Cancer Research (ICR), and published in Proceedings of the National Academy of Sciences, used advanced genetic fingerprinting to prove that an infant’s leukemic cells were unquestionably of maternal origin.
The case, involving a Japanese mother aged 28 and her daughter, revealed that both patients’ leukemic cells carried the identical mutated cancer gene BCR-ABL1 even though the infant had not inherited this gene.
This meant that the child, who had cancer diagnosed at 11 months old, could not have developed this type of leukemia in isolation.
Heart cancer is extremely rare and is referred to as cardiac sarcoma (cancer of a soft tissue). The number of people dying of heart cancer is combined with those dying of all soft tissue cancer and is estimated to be 4,000 people in 2010.
Many people diagnosed with heart cancer had a primary cancer close to the heart like melanoma and then it went on to invade the heart cells too. Tumors found in the heart are usually benign and can be removed.
It looks like research articles on cyclin have been published regularly over the past twenty years. In fact the 2001 Nobel Prize in Physiology or Medicine was awarded for the discovery of CDKs and cyclins and the complete description of cyclin and cyclin-dependent kinase mechanisms.
You remember from our textbook that when cyclin is injected into a non-dividing cell it begins to form spindles and goes into cell division. A research article published in 2008 found that cyclin d1 is over-expressed in human breast cancer. These findings may explain how cyclin d1 contributes to breast tumor growth, and provides the rationale for targeted therapies in humans.
In April 2010, over 50 abstracts were presented at the American Association of Cancer Research meeting dealing with cyclins and ways to inhibit the cyclin dependent kinase. It looks like a very promising area of cancer study.
Sources: ErbB2 Induces Notch1 Activity and Function in Breast Cancer Cells Clinical
and Translational Science Volume 1, Issue 2, pages 107–115, September 2008
Studying about cell division always brings up great questions about cancer.
One very recent discovery is the develop of blood vessels in tumors which serves as a pipeline for nourishment. It appears that tumors have hormone receptors that allows a hormone called FSH (follicle stimulating hormone) to bind and start forming new blood vessels. This receptor was found in 11 different types of tumors and the race is on to see if compounds can be used to block the receptor or inhibit the protein.
Source: A. Radu et al. Expression of follicle-stimulating hormone receptor in tumor blood vessels. New England Journal of Medicine, Vol 363, Oct 21, 2010, p.1621.
Friday, October 8, 2010
Sleep consists of three stages plus a stage of rapid eye movement know as REM. When a person enters stage 3, extremely slow brain waves called delta waves are interspersed with smaller, faster waves which progress into delta waves almost exclusively. Stages 3 is referred to as deep sleep or delta sleep, and it is very difficult to wake someone from it.
In deep sleep, there is no eye movement or muscle activity. This is when some children experience bedwetting, sleepwalking or night terrors. Adults spend about 20%of their sleep time in REM and about 15% of their time in Stage 3.
Eye color is genetically determined and is not as simple as once thought. The color of the eye is determined by multiple genes allowing for many different shades of gray, gree, blue and brown.
Eye color can change as a person grows older although most colors are permanent by age one.
Thursday, October 7, 2010
Cells growth and division is controlled by genes. One part of the gene stimulates and growth and another part of the gene restrains it. Those two pieces need to work in perfect harmony in order to have a normal rate of cell division. When cells divide much faster than usual they form a tumor. All cancers develop from a primary tumor.If the tumor sheds cells in the blood or lymph they will go on to form a secondary tumor elsewhere in the body.
Wednesday, October 6, 2010
The beauty of a stem cell is that it can develop into any type of cell. The stem cell is described as being pluripotent meaning that it is capable of generating any and all cells in the body under the right conditions.
So theoretically, a stem cell can be grown into a muscle cell however, right now the focus of researchers is on repairing diseased cells with new ones. So stem cells grown into muscle cells would be used to help someone with Muscular Dystrophy not a body builder.
Bruises hurt because they are the physical evidence of an injury. When a bruise appears it means that the tissue below has been damaged and blood vessels have broken beneath the skin. The swelling of the area due to escaping blood irritates the nerve endings in the area and you perceive pain.
Light bruising usually fades in about one week.
Tuesday, September 21, 2010
It appears that researchers have located spotted salamanders that have photosynthetic algae living inside their cells. This intracellular algae are providing the products of photosynthesis, oxygen and water, to the salamander's cells. This is the first time a relationship between algae and a vertebrate has been discovered.
The researcher, Ryan Kerney, says "the surrounding salamander cells that contain the algae often have several mitochondria bordering the algal symbiont" This makes it very convenient for the cells to use the glucose made during photosynthesis and turn it into ATP.
Tuesday, September 7, 2010
This question gets asked about a lot of sea animals. Most animals need down time to re-energize or evade predators. While this is often called "sleep", sometime hibernation might be a slightly closer term.
Fish do not have sleep like higher primates. They do not close their eyes or have REMs but scientists feel certain they experience a rest period when all body functions have slowed to a minimal level.
Genes contained DNA can be turned off and on through several methods. One of the most promising ways of altering genes is through epigenetics. Many studies have indicated that the environment plays a role in activating or silencing certain genes. Most of the changes attributed to epigenetics only last for one generation meaning they may not be passed on to offspring.
Epigenetics has been offered as one possible process affecting obesity. An environment of high fat/fast foods may turn on a gene promoting weight gain while in another eating environment, this gene would be silenced.
Thursday, September 2, 2010
Equine Thrush is caused by an anaerobic bacteria that gives rise to the growth of a fungus (yeast). If a horse is kept in a stall that is clean and dry it should never get Equine Thrush. Introducing oxygen into the stall shaving through use of a shovel or pitch fork will take care of any anaerobic bacteria as they diet as soon as they come into contact with air.
If thrush does manage to creep up on you and your horse, don't worry – treating it is actually fairly simple. You might first call your farrier so that he can thoroughly clean and trim your horse's hooves (particularly the frog area). This will make it easier for your horse's hooves to aerate, plus you can apply medication more directly to the infected areas.
Two products that are highly regarded by farriers for their effectiveness are Kopertox and Thrush Remedy by Absorbine, but just squirting some on the hoof generally isn't enough since the liquid may not reach all the nooks and crannies of the infected frog. Instead of squirting those products onto the infected area try applying the medication with a cotton swab. (Wrapping cotton around a stick or hoof pick does the trick.)
DO NOT apply bleach or hydrogen peroxide to a horse’s feet. These so-called “treatments” will burn the healthy tissues of the frog and actually retard healing.
Wow, that is deep question for the first one of a new school year! If I answered that only from the viewpoint of a scientist I would have to say yes. Especially in biology we see that the world and the species in it are constantly in flux.
However,as a Christian I have great comfort in knowing that one thing never changes and that's God's unfailing love for me. He has promised to never leave us or forsake us. This belief allows me to live with confidence in a world that seems to always be in a state of constant change.
However,as a Christian I have great comfort in knowing that one thing never changes and that's God's unfailing love for me. He has promised to never leave us or forsake us. This belief allows me to live with confidence in a world that seems to always be in a state of constant change.
Monday, May 10, 2010
Sleeping pills can be addictive over time. Not being able to get asleep or stay asleep is a common problem making sleeping pills a frequently used solution.
Sleeping pills work on the central nervous system and slow down the nerve impulses to the brain. Some sleeping pills can make you feel thick headed the next morning. With regular use your body develops a tolerance and requires a higher dose to put you to sleep.
There are several over the counter sleeping aids that are not addictive and are best for people with only occasional sleeping problems. If you're struggling with chronic insomnia, don't rely on antihistamines or other over-the-counter sleep aids for a good night's sleep. Lifestyle changes — rather than sleep aids — are usually the best approach. Start with the basics, such as:
■Following a regular sleep schedule
■Avoiding caffeine and daytime naps
■Including physical activity in your daily routine
Wednesday, May 5, 2010
Whales, dolphins and manatees have very efficient lungs. Even though the lung volume is less than terrestrial animals, they can exchange up to 85-90% of the air, whereas a human exchanges only 15% of the air.
This efficiency in breathing allows aquatic mammals to be submerged for several minutes to almost an hour. Air is breathed through blowhole, situated almost directly on top of the head. The dolphin normally comes to the surface to breathe about every two minutes,and each breath consists of a short, almost explosive exhalation, followed by a slightly longer inhalation.
I can see why you might think that since they are such slow moving animals. However, Manatees are mammals and ALL mammals have a four chamber heart which pumps into and out of vessels in a closed system. This allows oxygen and nutrients to be carried effectively through out the body.
Tuesday, May 4, 2010
While both of these orders are mammals, there are several unique characteristics that distinguish one from another. For example, a xenarthran has unique joints in their backbone that provide extra strength and support when digging and burrowing, few or no teeth and a small brain. Common critters in this group are armadillos and sloths.
Rodents on the other hand, are well known for their gnawing ability and have a pair of incisors in both the top and bottom jaws that never stop growing. Your first thought of a member of this order is a rat but beavers and gophers also fall into this group.
Yes, crabs are an example of the phylum Crustacea and are the most successful of the extant marine arthropods. Crabs have cephalization but are still able to move sideways. This is because animals in this phylum have many sophisticated appendages that help them sense the environment around them for example lobsters and crayfish can have multiple pairs of antennae, mouth parts, legs, and swimming appendages making them adept at moving forward or sideways. All of this sensory information is still processed in the head region of the crab.
Monday, May 3, 2010
Sharks are unique in several different ways:
1. They are made up entirely of cartilage which makes establishing a fossil history of these fish impossible.
2. Their skin is covered with denticles, which are tooth-like projections from the skin instead of scales.
3. They have no swim bladder. A very oily liver also provides buoyancy
to compensate for the lack of a swim bladder.
4. The jaw of a shark can be unhinged to open very wide while feeding. They also can
have as many as 8 rows of teeth.
5. Whenever a shark loses a tooth, another one moves up to take its
place. A shark can go through up to 2,400 teeth a year.
Sharks can be oviparous, ovoviviparous, and viviparous.
In oviparous sharks, a gland secretes a shell, or case, around the egg as it passes through the oviduct, protecting the shark until it hatches. The mother deposits the egg cases in the sea. Examples in this group include horn sharks and swell sharks.
In ovoviviparous sharks, the shell is often just a thin membrane. Sometimes there is more than one egg in the membrane; this group of eggs is called a candle. The mother retains the egg, and the embryo soon sheds the membrane and develops in the mother's uterus. An example of a shark that develops in this manner is a sand shark.
In viviparous sharks, the embryo receives all its nutrients from the mother. Tissues of the embryo and the mother are in intimate contact and nutrients are passed directly from the tissues of the mother to the tissues of the developing embryo.A hammerhead shark is an example of a viviparous fish.
Friday, April 30, 2010
The eel is really not an eel - it is closer to a carp and yes, it does generate electricity!
These awesome freshwater predators get their name from the huge electrical charge they can generate to stun prey and avoid predators. Their bodies contain electric organs with about 6,000 specialized cells called electrocytes that store power like tiny batteries. When threatened or attacking prey, these cells will discharge simultaneously, sending out a burst of at least 600 volts, five times the power of a standard U.S. wall socket.
If you want to see these fish in their natural habitat you need to travel to South America. There they grow to be over 8 feet (2.5 meters) in length and 44 pounds (20 kilograms) in weight.
Thursday, April 29, 2010
A fish does eat with its mouth and has many organs that are similar to a human so your question is logical.
The buccal cavity of the mouth secretes mucus to aid in the swallowing of food, but there are no salivary glands. This mucus is a only a lubricant, it contains no digestive enzymes like mammalian saliva. So no food is chemically altered in the mouth.
The Snook is a spectacular fish with extreme fighting power.A snook may be as long as 48 inches and weigh up to 38 pounds. In a fight with an angler, snook often swim toward structures, such as docks, rocks or pilings, using these structures to tangle and break fishing lines. These fish also have razor-sharp plates on their gills. During a struggle, the snook will twist and turn, fighting to cut the fishing line with its sharp gill plate.
This fish puts the sport into Florida fishing!
Wednesday, April 28, 2010
Several scientific sleep laboratory studies have shown that dreamers who were born blind and those who became blind in infancy do not have visual imagery in their dreams, whereas those blinded in adolescence or young adulthood often retain visual mental imagery in their waking life and in their dreams.
These controlled experiments confirm what has been reported in a number of earlier self-report studies reviewed by Kirtley (1975), who concluded that individuals blinded before the age of about 5 report no visual imagery in dreams as adults, whereas those blinded after about the age of 7 are likely to retain visual imagery in dreaming.
Tuesday, April 27, 2010
Starfish come in lots of different varieties, one recent count numbered the species in this class at about 1500! So, to answer your question, some starfish have more than five arms, in fact one, the Helicoilaster has 50 arms which all radiate from the central body part.
In addition to arms in multiples of five, many echinoderms have the remarkable ablitity to regenerate lost arms. In some cases, lost arms have been observed to regenerate a second complete sea star.
Monday, April 26, 2010
Many itches have medical causes like dry skin, insect bites, allergic reactions and psoriasis. If itching is caused by one of these it is best to refrain from scratching the site. As you may have experienced, scratching feels good for only a second and then the area itches worse than ever. Also, the bacteria under your nails may be enough to cause an infection at the site of the itch.
It appears that cold and itch travel the same nerve pathways so you can stop an itch by blocking the pathway with cold. Ice packs and menthol may temporarily stop an itch and can be reapplied frequently.
Friday, April 23, 2010
I think we will bust a commonly held myth with the answer to your question.
Several years ago a TV show recommended urine after a jellyfish sting. In reality, urine could make the sting situation worse. Jellyfish, those bulbous Medusa-like creatures, float near many of the world's beaches. Some of the jellyfish's skin cells are stinging cells, or cnidocytes. These specialized cells have organelles called nematocysts that contain venom. Cnidocytes are spread along the entire length of the jellyfish's tentacles.
Once stung, angry, red, whiplike lash marks appear on the skin. The pain radiates from the sting site and starts to itch, burn and throb as it blisters. Scratching it, though, can make the pain worse, because rubbing activates the nematocysts, which release more venom. The best treatment is to rinse off the nematocysts with salt water. Urine may be too dilute and not contain enough salts to be effective in getting rid of the stingy darts, in fact, dilute urine may cause the nematocysts to fire causing even more pain.
Thursday, April 22, 2010
Jellyfish are interesting animals but not ones that you would want to get real close to.
During their life cycle, jellyfish experience an alternation of generations in which one generation (the medussa) reproduces sexually and the next generation (the polyp) reproduces asexually. The medusa form is the dominant and most recognized form of the jellyfish.
In the first part of a jellyfish's life it is a stationary polp and is attached to a substrate. A polyp is cylindrical and stalk-like in form. At its base is a disc that adheres to the substrate and its top is a mouth opening surrounded by small tentacles. The polyp feeds by drawing food into its mouth. It grows and begins to bud new polyps from its trunk. As it does, the polyp develops into what is called a polyp hydroid colony. Members of the polyp colony are linked together by feeding tubes. The entire polyp hydroid colony, like the originating polyp, is sessile. The polyp colony can grow for several years. When polyps within the colony reach an adequate size, they are ready to begin the next stage in the jellyfish life cycle - the adult medusa.