Common Animal Questions and Answers

White Tiger Cubs
A gene mutation causes some tigers to have a white coat. Credit: IƱaki Respaldiza/Getty Images

Common Animal Questions and Answers

The animal kingdom is fascinating and often inspires a number of questions from both the young and old. Why do zebras have stripes? How do bats locate prey? Why do some animals glow in the dark? Find answers to these and other intriguing questions about animals.

Why Do Some Tigers Have White Coats?

Researchers from China's Peking University have discovered that white tigers owe their unique coloration to a gene mutation in the pigment gene SLC45A2.

This gene inhibits the production of red and yellow pigments in white tigers but does not appear to alter black. Like orange Bengal tigers, white tigers have distinctive black stripes. The SLC45A2 gene has also been associated with light coloration in modern Europeans and in animals such as fish, horses, and chickens. The researchers advocate for the possible reintroduction of white tigers into the wild. Current white tiger populations only exist in captivity as wild populations were hunted out in the 1950s.

Do Reindeer Really Have Red Noses?

A study published in the BMJ-British Medical Journal reveals why reindeer have red noses. Their noses are abundantly supplied with red blood cells through nasal microcirculation. Microcirculation is the flow of blood through tiny blood vessels. Reindeer noses have a high density of blood vessels that supply a high concentration of red blood cells to the area.

This helps to increase oxygen to the nose and to control inflammation and regulate temperature. The researchers used infrared thermal imaging to visualize the reindeer's red nose.

Why Do Some Animals Glow In the Dark?

Some animals can emit light naturally due to a chemical reaction in their cells. These animals are called bioluminescent organisms.

Some animals glow in the dark to attract mates, to communicate with other organisms of the same species, to lure prey, or to expose and distract predators. Bioluminescence occurs in invertebrates such as insects, insect larvae, worms, spiders, jellyfish, dragonfish, and squid.

How Do Bats Use Sound to Locate Prey?

Bats use echolocation and a process called active listening to locate prey, typically insects. This is particularly helpful in clustered environments where sound can bounce off of trees and leaves making it more difficult to locate prey. In active listening, bats adjust their vocal cries emitting sounds of variable pitch, length, and repetition rate. They can then determine details about their environment from the returning sounds. An echo with a sliding pitch indicates a moving object. Intensity flickers indicate a fluttering wing. Time delays between cry and echo indicate distance. Once its prey has been identified, the bat emits cries of increasing frequency and decreasing duration to pinpoint its prey's location. Finally, the bat emits what is known as the final buzz (rapid succession of cries) before capturing its prey.

Why Do Some Animals Play Dead?

Playing dead is an adaptive behavior used by a number of animals including mammals, insects, and reptiles.

This behavior, also called thanatosis, is most often employed as a defense against predators, a means to catch prey, and as way of avoiding sexual cannibalism during the mating process.

Are Sharks Color Blind?

Studies on shark vision suggest that these animals may be completely color blind. Using a technique called microspectrophotometry, researchers were able to identify cone visual pigments in shark retinas. Of the 17 shark species studied, all had rod cells but only seven had cone cells. Of the shark species that had cone cells, only a single cone type was observed. Rod and cone cells are the two main types of light sensitive cells in the retina. While rod cells can not distinguish colors, cone cells are capable of color perception. However, only eyes with different spectral types of cone cells can distinguish different colors.

Since sharks appear to have only a single cone type, it is believed that they are totally color blind. Marine mammals such as whales and dolphins also have only a single cone type.

Why Do Zebras Have Stripes?

Researchers have developed an interesting theory as to why zebras have stripes. As reported in the Journal of Experimental Biology, zebra's stripes help to ward off biting insects such as horseflies. Also known as tabanids, horseflies use horizontally polarized light to direct them toward water for laying eggs and to locate animals. The researchers state that horseflies are more attracted to horses with dark hides than those with white hides. They concluded that the development of white stripes prior to birth helps to make zebras less attractive to biting insects. The study indicated that the polarization patterns of reflected light from zebra hides were consistent with stripe patterns that were least attractive to horseflies in tests.

Can Female Snakes Reproduce Without Males?

Some snakes are capable of reproducing asexually by a process called parthenogenesis. This phenomenon has been obeserved in boa constrictors as well as in other animals including some species of shark, fish, and amphibians. In parthenogenesis, an unfertilized egg develops into a distinct individual. These babies are genetically identical to their mothers.

Why Don't Octopuses Get Tangled in Their Tentacles?

Hebrew University of Jerusalem researchers have made an interesting discovery that helps answer the question of why an octopus doesn't get tangled up in its tentacles. Unlike in the human brain, the octopus brain does not map out the coordinates of its appendages. As a result, octopuses don't know where their arms are exactly. To prevent the octopus's arms from grabbing the octopus, its suckers will not attach to the octopus itself. The researchers state that an octopus produces a chemical in its skin that temporarily prevents the suckers from grabbing. It was also discovered that an octopus can override this mechanism when necessary as evidenced by its ability to grab an amputated octopus arm.

Sources:

  • Cell Press. "White tiger mystery solved: Coat color produced by single change in pigment gene." ScienceDaily. ScienceDaily, 23 May 2013. (www.sciencedaily.com/releases/2013/05/130523143342.htm).
  • BMJ-British Medical Journal. "Experts discover why Rudolph's nose is red." ScienceDaily. ScienceDaily, 17 December 2012. (www.sciencedaily.com/releases/2012/12/121217190634.htm).
  • Chanut F (2006) The Sound of Dinner. PLoS Biol 4(4): e107. doi:10.1371/journal.pbio.0040107.
  • Springer Science+Business Media. "Are sharks color blind?." ScienceDaily. ScienceDaily, 19 January 2011. (www.sciencedaily.com/releases/2011/01/110118092224.htm).
  • The Journal of Experimental Biology. "How the zebra got its stripes." ScienceDaily. ScienceDaily, 9 February 2012. (www.sciencedaily.com/releases/2012/02/120209101730.htm).
  • Cell Press. "How octopuses don't tie themselves in knots." ScienceDaily. ScienceDaily, 15 May 2014. (www.sciencedaily.com/releases/2014/05/140515123254.htm).