Animal Life

How much electricity does an electric eel generate?

The quick answer is that a mature electric eel can produce a shock up to 500 volts at 1 amp of current (500 watts).  The eel’s organs are capable of producing two types of electric discharge– low voltage and high voltage. Both could be harmful to an adult human.

The longer answer, or exactly how the electric eel produces electricity is a bit more complex. Basically, the electric eel has three abdominal pairs of organs that produce electricity. They’re called the Sachs organ, the hunter’s organ and the main organ. The eel’s vital organs are contained in the first one fifth  of its body whereas these electricity producing organs are in the remainder four fifths.

These organs are made of electrocytes lined up in series so the current flows through them and produces an electrical charge. When the eel locates its prey, the brain sends a signal through the nervous system to the electric cells. This opens the ion channel, allowing positively-charged sodium to flow through, reversing the charges momentarily. By causing a sudden difference in voltage, it generates a current. The electric eel generates its characteristic electrical pulse in a manner similar to a battery, in which stacked plates produce an electrical charge. [wikipedia]

Which mammal has the shortest gestation period?

The shortest known gestation period is 12 to 13 days. This record is shared by three marsupials, which is kind of an unfair comparison to all other mammals as in marsupials, the young are born immature and have to continue developing in a pouch on the mother. The three mammals with this very quick gestation period are:  the American or Virginian opossum (Didelphis marsupialis); the rare water opossum, or yapok (Chironectes minimus), of central and northern South America; and the eastern native cat (Dasyurus viverrinus) of Australia.

More about the Virginia Opossum [source: Wikipedia]

It is the largest member of its genus, family and order and is the largest of the opossums. They are typically 15–20 inches (38–51 cm) long and weigh between 9 and 13 pounds (4–6 kg). Their coats are a dull grayish brown, other than on their faces, which are white. Opossums have long, hairless, prehensile tails, which can be used to grab branches and carry small objects. They also have hairless ears and a long, flat nose. Opossums have 50 teeth and opposable, clawless thumbs on their rear limbs.

What is echolocation?

Echolocation is the ability to locate objects by bouncing sound waves off of them, and then measuring the time taken for an echo to return, and calculating the direction the echo came from.

These sound waves are very high-pitched, and most humans are unable to hear them. A device called a bat detector is able to pick up these sounds and convert them into sounds which we can hear as a series of clicks, pops and whistles.

Source: http://www.uksafari.com/bats4.htm.

How did the zebra get its stripes?

Another interesting question to first consider is: is a zebra a light animal with dark stripes, or a dark animal with light stripes? It’s generally believed that a zebra is a dark animal with light stripes. Most scientists believe that the zebra evolved from a horse-like animal with no stripes.

One theory of where the stripes came from is simply natural selection. Over millions of years, a few zebra foals were born with lighter colored stripes in a process called “accidental variation.” These foals had a marked advantage over their darker colored siblings and thus went on to reproduce in greater numbers, creating more striped offspring.

But how exactly did having stripes create an advantage? Think of an ordinary dark colored horse standing on a hillside. Its silhouette would make it stand out from the background, and would tell a hungry lion exactly where his next meal might come from. Now imagine a striped animal. It’s silhouette would be a bit more mottled and generally different. This likely gave it a camouflaged advantage and probably spared a few animals from hungry lions.

A couple of good sources of information on zebra biology are: Developmental Biology, and the Wikipedia article on zebras.

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What are the oldest living animals?

The claim for oldest animal often goes to the Arctica Islandica clam – one estimated to be 405 years old was found while British scientists were studying how the marine environment has changed in recent centuries. Unfortunately this Arctica Islandica clam was killed when scientists were counting annual growth rings after cutting through the shell. Marine biologists are uncertain why the particular species of clam is so long-lived.

According to the Guinness Book of World Records, the current claim for the oldest animal goes to another Arctica clam that lived for 220 years. An unofficial record is held by yet another clam that lived to be 374 years old, which is now in a German museum.

The Adwaitha Tortoise is another long-lived animal. British General Robert Clive had brought one to India when it was 250 years old. It lived 59 more years and became a special attraction in Alipore Zoological Park, Kolkata, India.

The Bowhead Whale is the oldest living mammal. Their lifespan can be as long as 210 years.

How many insect species are there?

While insects are the most diverse group of animals on the planet, we don’t have a very accurate count on the number of species. There are over one million named species, but many scientists estimate the number of unnamed species to be as high as 30 million. Even considering only the million or so insects that we have formally classified, this number still represents over half of all known living organisms. When we consider the total possible number of insects (maybe more than 30 million), these would represent up to 90% of all known animals. Note: Wikipedia cites the most current estimates of unnamed insects to be between 6-10 million.

Some of the numbers of insects by species are:

• Beetles, 360,000
• Butterflies and Moths: 170,000
• Flies: 120,000
• Bees, wasps and ants: 110,000
• True bugs: 82,000
• Grasshoppers: 20,000
• Dragonflies: 2,000

What is the largest bear ever recorded?

While the American grizzly bear is fearsome and cool to look at, the polar bear is generally considered the largest bear in the world. Its average weight is between 900 and 1500 pounds. The brown bear, averaging 500 to 900 pounds a close second.

The biggest polar bear ever recorded was a male shot in Kotzebue Sound in Alaska in 1960 weighing an amazing 2,210 pounds (1002 kilograms) and was 11 feet 11 inches in height. Source: Wood, G.L. (1981). The Guinness Book of Animal Records. pp. 240.