The colour red represents anger. The hippopotamus, the second largest land animal after the elephant, spends most of its time partly submerged in a river. When the hippo does climb out of the water, its skin often secretes drops of a bright red liquid that looks just like blood. Some circuses used to claim that they had "blood-sweating hippos" on display, but this red liquid is not blood - it's sweat.
The hippo secretes a red oil that mixes with its sweat to keep the hippo's hide moist and soft, thus preventing it from drying out in the hot sun. No, that's hippos. Hippos do it because they have very fair skin, and the red pigment in their sweat acts as a sunscreen and stops them from burning up. Red is supposed to anger, however, when a person becomes angry, colour has very little to do with it. In the western world, red is associated with anger and danger.
Sometimes you turn red when you get angry. Red and black. Log in. Animal Life. Study now. See Answer. Best Answer. Study guides. Where are in the animal nutrition in M P. Genetics 20 cards. Go Paperless with Digital.
Mark Ritchie, a professor of biology at Syracuse University, provides the following explanation: HIPPOS spend most of their day resting in water and can hold their breath for up to 30 minutes. Get smart. Sign Up. Support science journalism. Droplets of perspiration resemble drops of blood, although blood would wash away in water, while hippo perspiration sticks to the animal's wet skin.
This is because the hippo's "blood sweat" contains a high amount of mucous. Yoko Saikawa and his research team at Kyoto Pharmaceutical University, Japan, identified non-benzenoid aromatic compounds as the orange and red pigment molecules.
These compounds are acidic, conferring protection against infection. The red pigment, called "hipposudoric acid"; and the orange pigment, called "norhipposudoric acid", appear to be amino acid metabolites. Both pigments absorb ultraviolet radiation, while the red pigment also acts as an antibiotic.
Pigment chemistry: The red sweat of the hippopotamus. Nature , 27 May Actively scan device characteristics for identification. Use precise geolocation data. Select personalised content. In a technique called pheromone mating disruption , synthetic female pheromone is released in crops or orchards in sufficient quantity that male moths cannot find the real females.
This technique is being used on more than 10 million hectares around the world. As is often the case, farmers turned to using pheromones when the moth became resistant to pesticides. Invasive, parasitic sea lampreys have decimated fisheries of the Great Lakes. Photograph courtesy of Great Lakes Fishery Commission. While the use of pheromones has been well established against insect pests, they could also be used to control vertebrate pests and human diseases.
For example, invading sea lampreys Petromyzon marinus , a parasitic jawless fish, have devastated the fisheries of the Great Lakes in North America. Pheromones could also be used to tackle human diseases such as those caused by parasitic nematode worms that use pheromones at crucial stages in their life cycle. One target species is the human parasitic nematode Strongyloides stercoralis , a cause of extensive morbidity in the developing world.
Because sea lamprey males use pheromones to draw females upstream to breed, traps baited with pheromones are being explored as a potential control. The species specificity of pheromones is one of their big advantages, because using them for pest control has fewer environmental impacts than broad-spectrum pesticides.
However, the specificity is a disadvantage for commercial development, because each pest species must be studied individually to identify its pheromones. Unlike the development of broad-spectrum insecticides, the research costs are not spread over many pests.
The organizations best placed to work on pheromones are universities and government research laboratories, but these are among those scientific institutions most threatened by spending cuts in many nations.
Although it is less profitable for corporations, pheromone-based pest control can be highly cost-effective compared with pesticides and has major benefits to the environment, farmers, and consumers. Broadcast signals can be "overheard" by unintended recipients. For example, alarm pheromones released by Solenopsis fire ants when fighting ants from other colonies attract unwelcome eavesdroppers: ant-decapitating flies, so named because these parasitic phorid flies lay their eggs in the heads of ants, which eventually fall off.
One of these phorid fly species, Pseudacteon tricuspis , might be introduced into the United States as a possible biological control of invasive fire ants.
A parasitic phorid fly Apocephalus sp. Illegal signalers make counterfeit pheromones as an aggressive form of mimicry. American bolas spider females lure male moths by mimicking the sex pheromones emitted by female moths of that species. If the bolas touches, moths rarely escape. The bolas spider lures in male moths by mimicking the pheromone of females.
Photograph courtesy of Kenneth F. Plants can deceive, too. Instead of giving a nectar reward, many orchids dupe male bees into pollinating them by counterfeiting the pheromone of a particular bee species.
For example, the European orchid, Ophrys sphegodes , almost perfectly mimics the multicomponent hydrocarbon female sex pheromone blend of the solitary bee, Andrena nigroaenea. Male bees, attracted by the counterfeit pheromone and the visual mimicry of the orchid flower, pick up a pollen pack as they attempt to mate with the flower. They later make the same mistake again and transfer the pollen to another orchid flower of the same species.
Skip to main content. Login Register. How Animals Communicate Via Pheromones By Tristram Wyatt Human behaviors are probably influenced by invisible smell signals, just like all other animals. Page DOI: Photograph by Alexander Wild.
Photograph courtesy of Sam Woo. Illustration by Barbara Aulicino. When molecules are added or lost from the cocktail of molecules as species diverge, each new species will have its own specific sex pheromone from these new combinations, even though the molecules themselves may not be especially unusual. Photograph by Ann Pettigrew. Photograph courtesy of www.
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Trends in Neurosciences — De Bruyne, M. Odor detection in insects: volatile codes. Doty, R. Human pheromones: Do they exist? In: Mucignat-Caretta, C ed. Neurobiology of chemical communication. Doucet, S. Soussignan, P. Sagot, and B. Hansson, B. Evolution of insect olfaction. Neuron — Johnson, N.
A synthesized pheromone induces upstream movement in female sea lamprey and summons them into traps. Proceedings of the National Academy of Sciences of the U. Kamakura, M. Royalactin induces queen differentiation in honeybees.
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