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Wednesday, April 2, 2008
Tuesday, February 12, 2008
Portuguese-man-o-war
Jellyfish (disambiguation).source...................www.wikipedia.com
Jellyfish are marine invertebrates belonging to the class Scyphozoa of the phylum Cnidaria. They can be found in every ocean in the world and in some fresh waters. The use of the term "jellyfish" is actually a misnomer since scyphozoans are not fish, which are vertebrates. Although incorrect, the term is also commonly-applied to some close relatives of true scyphozoans, such as the Hydrozoa and the Cubozoa
A typical medusoid-phase jellyfish. 
The developmental stages of jellyfish. 
A group of Sea Nettle jellyfish in an aquarium.
| Jellyfish | ||||||
|---|---|---|---|---|---|---|
 Sea nettle, Chrysaora quinquecirrha | ||||||
| Scientific classification | ||||||
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| Orders | ||||||
Anatomy and morphology
The body of an adult jellyfish consists of a bell shape producing jelly and enclosing its internal structure, from which tentacles are suspended. Each tentacle is covered with cells called cnidocytes, that can sting or kill other animals. Most jellyfish use these cells to secure prey or for defense. Others, such as the Rhizostomae, do not have tentacles at all.
Jellyfish lack basic sensory organs and a brain, but their nervous systems and rhopalia allow them to perceive stimuli, such as light and odor, and respond quickly. They feed on small fish and zooplankton that become caught in their tentacles. Most jellyfish are passive drifters and slow swimmers, as their shape is not hydrodynamic. Instead, they move so as to create a current forcing the prey within reach of their tentacles. They do this by rhythmically opening and closing their bell-like body. Their digestive system is incomplete: the same orifice is used to take in food and expel waste. The body of an adult is made up of 94–98% water. The bell consists of a layer of epidermis, gastrodermis, and a thick, intervening layer called mesoglea that produces most of the jelly.
[edit] Defense
Most jellyfish have tendrils or oral arms coated with thousands of microscopic nematocysts. Generally, each nematocyst has a "trigger" (cnidocil) paired with a capsule containing a coiled stinging filament armed with exterior barbs. Upon contact, the filament rapidly unwinds, launches into the target, and injects toxins. The animal can then pull its prey into its mouth, if appropriate.
Although most jellyfish are not perniciously dangerous to humans, a few are highly toxic, such as Cyanea capillata. Contrary to popular belief, the menacingly infamous Portuguese Man o' War (Physalia) is not a jellyfish but a colony of hydrozoans. Similarly, the box jellies, notorious along the coast of Australia, are cubozoans, not true scyphozoan jellyfish. Irrespective of the sting's toxicity, many people stung by them find them very painful and some people may suffer anaphylaxis or other severe allergic reactions, similar to allergies to bee stings.[1]
[edit] Body systems
A jellyfish detects the touch of other animals using a nervous system called a "nerve net", located in its epidermis. Touch stimuli are conducted by nerve rings, through the rhopalial lappet, located around the animal's body, to the nerve cells. Jellyfish also have ocelli: light-sensitive organs that do not form images but are used to determine up from down, responding to sunlight shining on the water's surface.
Jellyfish do not have a specialized digestive, osmoregulatory, central nervous, respiratory, or circulatory systems. They digest using the gastrodermal lining of the gastrovascular cavity, where nutrients are absorbed. They do not need a respiratory system since their skin is thin enough that the body is oxygenated by diffusion. They have limited control over movement and mostly free-float, but can use the hydrostatic skeleton of the water pouch to accomplish vertical movement through pulsations of the disc-like body.
The outer side of a jellyfish is lined with a jelly-like material called ectoplasm (ecto meaning outer and plasma meaning cytoplasm). The ectoplasm typically contains a smaller amount of protein granules and other organic compounds than inner cytoplasm, also referred to as endoplasm (endo meaning inner).
Many species of jellyfish are capable of congregating into large swarms or "blooms", consisting of hundreds of individuals. The formation of these blooms is a complex process that depends on ocean currents, nutrients, temperature and ambient oxygen concentrations. Jellyfish sometimes mass breed during blooms. During such times of rapid population expansion, some people will raise ecological concerns about the potential noxious effects of a jellyfish "outbreak".
According to Claudia Mills of the University of Washington, the frequency of jellyfish blooms may be attributed to man's impact on marine systems. She says that the breeding jellyfish may merely be filling ecological niches formerly occupied by overfished creatures. Jellyfish researcher Marsh Youngbluth further clarifies that "jellyfish feed on the same kinds of prey as adult and young fishes, so if fish are removed from the equation, jellyfish are likely to move in."
Increased nutrients in the water, ascribed to agricultural runoff, have also been cited as an antecedent to the proliferation of jellyfish. Monty Graham, of the Dauphin Island Sea Lab in Alabama, says that "ecosystems in which there are high levels of nutrients ... provide nourishment for the small organisms on which jellyfish feed. In waters where there is eutrophication, low oxygen levels often result, favoring jellyfish as they thrive in less oxygen-rich water than fish can tolerate. The fact that jellyfish are increasing is a symptom of something happening in the ecosystem."[2]
By sampling sea life in a heavily fished region off the coast of Namibia, researchers found that jellyfish have overtaken fish in terms of biomass. The findings represent a careful, quantitative analysis of what has been called a "jellyfish explosion" following intense fishing in the area in the last few decades. The findings were reported by Andrew Brierley of the University of St. Andrews and his colleagues in the July 12, 2006 issue of the journal Current Biology.
Areas which have been seriously affected by jellyfish blooms include the northern Gulf of Mexico. In that case, Graham states, "Moon jellies have formed a kind of gelatinous net that stretches from end to end across the gulf."[2]
[edit] Life history
Most jellyfish pass through two distinct life history phases (body forms) during their life cycle. The first is the polypoid stage, when the jellyfish takes the form of either a sessile stalk which catches passing food, or a similar free-floating configuration. The polyp's mouth and tentacles face upwards, reminiscent of the hydroid stage of the somewhat closely related anthozoan polyps, also of the phylum Cnidaria.
In the second stage, the jellyfish is known as a medusa. Medusae have a radially symmetric, umbrella-shaped body called a bell. The medusa's tentacles are fringe-like protrusions from the border of the bell. (Medusa is also the Hebrew, Spanish, Italian, Russian and Bulgarian word for jellyfish.)
Jellyfish are dioecious; that is, they are either male or female. In most cases, to reproduce, a male releases his sperm into the surrounding water. The sperm then swims into the mouth of the female, allowing the fertilization of the ova. However, moon jellies use a different process. The eggs become lodged in pits on the oral arms, which form a temporary brood chamber to accommodate fertilization.
After fertilization and initial growth, a larval form, called the planula, develops from the egg. The planula is a small larva covered with cilia. It settles onto a firm surface and develops into a polyp. The polyp is cup-shaped with tentacles surrounding a single orifice, resembling a tiny sea anemone. After an interval of growth, the polyp begins reproducing asexually by budding and is called a segmenting polyp, or a scyphistome. New scyphistomae may be produced by budding or new, immature jellies called ephyra may be formed. Many jellyfish species are capable of producing new medusae by budding directly from the medusan stage.
Most jellyfish have a lifespan of two and a half months; few live longer than six months but one species can live as long as 30 years and another species, T. nutricula, is effectively immortal.
[edit] Etymology and taxonomic history
Since jellyfish are not fish, some people consider the term "jellyfish" a misnomer, and instead use the term "jellies" or "sea jellies". The word "jellyfish" is also often used to denote either hydrozoans or the box jellyfish, the cubozoans. The class name, Scyphozoa, comes from the Greek word skyphos, denoting a kind of drinking cup and alluding to the cup shape of the organism.
A group of jellyfish is often called a "smack". [3]
[edit] Importance to humans
[edit] Culinary uses
Jellyfish are an important source of food to the Chinese community and in many Asian countries.[4] Only jellyfish belonging to the order Rhizostomeae are harvested for food. Rhizostomes (especially Rhopilema esculentum, Chinese name: 海蜇 hǎizhē) are favoured because they are typically larger and have more rigid bodies than other scyphozoans. Traditional processing methods involve a multi-phase procedure using a mixture of table salt and alum, and then desalting.[4] Processing makes the jellyfish drier and more acidic, producing a "crunchy and crispy texture."[4] Nutritionally, jellyfish prepared this way are roughly 95% water and 4-5% protein, making it a relatively low calorie food.[4]
[edit] In biotechnology
In 1961, green fluorescent protein was discovered in the jellyfish Aequorea victoria by scientists studying bioluminescence. This protein has since become a quite useful tool in biology. Its use is mainly for scientists studying in which tissues genes are expressed. The technique uses genetic engineering fuse the gene of interest to the gene of GFP. the fused DNA is then put into a cell, to generate either a cell line or (via IVF techniques) an entire animal bearing the gene. In the cell or animal, the artificial gene gets turned on the same tissues and the same time as the normal gene. But instead of making the normal protein, the gene makes GFP. You can then find out what tissues express that protein, or at what stage of development - by shining light on the animal or cell, and looking for the green fluorescence. The fluorescence shows you where the gene you are interested in is expressed. [5] Jellyfish are also harvested for their collagen, which can be used for a variety of scientific applications including the treatment of rheumatoid arthritis.
[edit] In captivity
Jellyfish are commonly displayed in aquaria in many countries; among them the Monterey Bay Aquarium, Long Beach Aquarium of the Pacific, Vancouver Aquarium, New York Aquarium,Seattle Aquarium, New England Aquarium, Newport Aquarium, National Aquarium in Baltimore, Georgia Aquarium and Maui Ocean Center. Often the tank's background is blue and the animals are illuminated by side light to produce a high contrast effect. In natural conditions, many jellies are so transparent that they are almost impossible to see.
Holding jellyfish in captivity presents other problems. For one, they are not adapted to closed spaces. They depend on currents to transport them from place to place. To compensate for this, professional exhibits feature precise water flows, typically in circular tanks to prevent specimens from becoming trapped in corners. The Monterey Bay Aquarium uses a modified version of the kreisel (German for "spinning top") for this purpose.
[edit] Toxicity to humans
When stung by a jellyfish, first aid may be in order. Though most stings are not deadly, some stings, such as those of the box jellyfish (Chironex fleckeri), may be fatal. However, even nonfatal jellyfish stings are known to be extremely painful. Serious stings may cause anaphylaxis and may result in death. Hence, people stung by jellyfish must get out of the water to avoid drowning. In serious cases, advanced professional care must be sought. This care may include administration of an antivenin and other supportive care such as required to treat the symptoms of anaphylactic shock. The most serious threat that humans face from jellyfish is the sting of the Irukandji, which has the most potent and deadly venom of any known species.
There are three goals of first aid for uncomplicated jellyfish stings: prevent injury to rescuers, inactivate the nematocysts, and remove any tentacles stuck on the patient. To prevent injury to rescuers, barrier clothing should be worn. This protection may include anything from panty hose to wet suits to full-body sting-proof suits. Inactivating the nematocysts, or stinging cells, prevents further injection of venom into the patient.
Vinegar (3 to 10% aqueous acetic acid) should be applied for box jellyfish stings.[6][7] Vinegar, however, is not recommended for Portuguese Man o' War stings.[6] In the case of stings on or around the eyes, vinegar may be placed on a towel and dabbed around the eyes, but not in them. Salt water may also be used in case vinegar is not readily available.[6][8] Fresh water should not be used if the sting occurred in salt water, as a change in pH can cause the release of additional venom. Rubbing the wound, or using alcohol, spirits, ammonia, or urine will encourage the release of venom and should be avoided.[9] Though often not available a shower or bath as hot as can be tolerated can neutralize stings. Be careful with this method if hypothermia is also suspected.
Once deactivated, the stinging cells must be removed. This can be accomplished by picking off tentacles left on the body.[9] First aid providers should be careful to use gloves or another readily available barrier device to prevent personal injury, and to follow standard universal precautions. After large pieces of the jellyfish are removed, shaving cream may be applied to the area and a knife edge, safety razor, or credit card may be used to take away any remaining nematocysts.[10]
Beyond initial first aid, antihistamines such as diphenhydramine (Benadryl) may be used to control skin irritation (pruritus).[10] To remove the venom in the skin, apply a paste of baking soda and water and apply a cloth covering on the sting. If possible, reapply paste every 15-20 minutes. Ice can be applied to stop the spread of venom until either of these is available.
[edit] Gallery
 Sea nettle Jellyfish (Chrysaora quinquecirrha) at the Monterey Bay Aquarium. |  Blubber jelly (Catostylus mosaicus) at the Monterey Bay Aquarium. |  Mastigias papua at the Monterey Bay Aquarium. |  Australian spotted jellyfish (Phyllorhiza punctata). |
 Mediterranean Jellyfish (Cotylorhiza tuberculata) at the Monterey Bay Aquarium. | |||
 Catostylus species of stingless jellyfish from Palau, Micronesia. |  Jellyfish in the river Guadiana, Vila Real de Santo António, Portugal |  West Coast Sea Nettle at the Long Beach Aquarium. |  Jellyfish at the Long Beach Aquarium. |
Spider and Daddy-long legs
A spider is an araneae, an order of arachnid. There are many thousand different kinds of spiders. All spiders have eight legs. Most spiders have eight eyes but some have fewer than eight. They don't have ears, they feel the sound vibrations with tiny hairs on their legs. Their bodies have two parts, the head and the abdomen. The abdomen is plump. Spider blood is light blue. Blood fills up all the empty space in the spider's body, it helps to keep the legs stiff so the spider can walk. Spiders breathe, too. As spiders grow, they molt. That means they shed their old skin and grow a new one. They molt many times before they become adults. Many spiders live for only one year but some, like tarantulas(top left) can live much longer. Spiders come in different sizes. Some are fuzzy and others are smooth, and they come in many different colors. Spiders live in many different kinds of places, water, gardens, houses, and the ground. They live where it is hot and where it is cold. They live where it is wet and where it is dry. Some are poisonous and others are not.
Widow spiders
The southern black widow, Latrodectus mactans(right), and its relatives live across the entire United States. Other widow species found in Texas are the western black widow, L. hesperus; the northern black widow, L. variolus; and probably the brown widow, L. geometricus. Their coloration varies considerably. For proper identification, an expert may be needed to examine mature specimens.
Widow spiders are found in protected cavities outdoors. Around houses, they may live in privies, garages, cellars, furniture, shrubbery, ventilators, rain spouts, gas and electric meters and other undisturbed places. Widow spiders also may be seen in cotton fields and occasionally vegetable gardens.
Like most spiders, widow spiders are shy and retiring. People are bitten occasionally when they accidentally disturb a hidden spider or its web. To avoid hidden spiders, take care when putting on seldom-worn shoes or clothing.
These are about spiders. But the daddy long-legs is not a spider.....
Many people think of the daddy long legs(top right) as a spider but it is not. The daddy long legs is one quarter to three eighths inches in length, with long thin legs. It is a yellowish, greenish brown with legs that are pale to dark. It prefers open areas on foliage and tree trunks or shady walls outside buildings. Daddy long legs have six eyes not eight eyes like other spiders. Daddy long legs hang upside down on its web. Daddy long legs eat other daddy long legs. Daddy long legs have many enemies. Daddy long legs like dark places and are often found in the basements of houses
Monday, February 11, 2008
The guppies..............love..........
The guppies ,they are my favorite..........are the few tropical aquarium fish that give the young ones .....without laying eggs...!!!
the males and females are highly differentiable ..males with bright colors and the females with dull colors . The males display their colors to attract the females to mate. the tiny guppies are vulnerable to the bigger ones as they make a good meal.....
The Physiology of Firefly
In order to communicate with each other and ward off predators, fireflies employ bioluminescence, a phenonmenon in which light energy is produced via internal chemical processes. 
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