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.