Testing on animals

Testing on animals

Animals perform the following functions: feeding, respiration, circulation, excretion, response, movement and reproduction:

Food: Most animals can not absorb food, the eat. Animals have evolved in different ways for food, herbivores eat plants, carnivores eat other animals, and omnivores eat both plants and animals, plant material and detritus feeders eat decomposing animal, filtered eaters are aquatic animals who strain tiny organisms that float in water. The animals also form symbiotic relationships, in which two species live in close association with each other. For example, a parasite is a type of symbiont that lives in or on another organism, the host. The parasite feeds on host and damages it.

Breathing: no matter if they live in water or on land all animals breathe, meaning they can take up oxygen and discharge carbon dioxide. Thanks to its very simple bodies of thin walls and some animals using the diffusion of these substances through the skin, most animals have evolved complex tissues and organ systems for respiration.

Circulation: Many small aquatic animals, as some worms, used only to transport oxygen diffusion and molecules of nutrients to all cells, and they collect the waste products. The spread just because these animals have only a few cells thick, larger animals have some type of circulatory system to move substances around inside their bodies.

Excretion: a primary waste product is ammonia cell, containing poisonous nitrogen, the accumulation of ammonia and other waste products could kill an animal, most animals have an excretory system that eliminates either ammonia or transforms it into a less toxic substance that leaves the body. Thanks to eliminate metabolic waste excretory systems help maintain homeostasis. Excretory systems ranging from cells that pump water out of the body to complex organs such as kidneys.

Answer: The animals use specialized cells called nerve cells to respond to events in their environment. In most animal nerve cells are connected together to form a nervous system. Some cells called receptors respond to sounds, light and other external stimuli, other nerve cells process information and determine the response of the animal. The organization of nerve cells within the body changes dramatically from one phylum to another.

 Movement: Some adult animals remain fixed in one place but many are mobile, however both fixed and typically possess faster muscles or muscle tissues which are shortened to generate force. Muscle contraction allows moving animals move often in combination with a structure called skeleton. Muscles also help animals, even the most sedentary, eat and pump water and other fluids from the body.

Reproduction: Most animals reproduce sexually by producing haploid gametes, sexual reproduction helps create and maintain genetic diversity of a population that helps improve the ability of a species to evolve with the changing environment. Many invertebrates can also reproduce asexually, asexual reproduction gives rise to offspring genetically identical to parents, this mode of reproduction allows the animals to increase rapidly in number.

The Lion

The lion is the second largest living cat after the tiger, with powerful limbs, a strong jaw and a three-inch canine teeth, the lion can kill large prey. The color of lions ranges from light beige to yellowish brown, reddish or umber, the bottoms are normally lighter and hair from the end of the tail is black. Lion pups have spotted a picture that is lost with age but sometimes can be seen in the legs and belly especially the lionesses.

Lions are the only cats that have a clear sexual dimorphism, males and females have strikingly different look because of the specialized roles they play within the group. For example, the lioness as the hunter, lacks the thick mane of the male, which would impair its ability to camouflage to prepare ambushes. The hair color ranges from blond to black and usually darker as the lion ages.

Males are easily distinguished by their long hair makes her head one of the most widely recognized animal symbols in human culture. Appears very often in literature, sculpture, painting, national flags and contemporary films and literature.

The lionesses do most of the hunting of the herd being smaller, faster and agile than the males in addition to not having the large and visible hair causing excess heat during physical exertion act as a coordinating group to increase the success of their hunts, males have a tendency to dominate the game once the lionesses have caught the prey in fact tend to share more hunting pups with the lionesses and rarely share what they have caught themselves. The smaller prey are consumed at the place where they have been hunted so that they are shared among the hunters, when the prey is larger drag it to the territory of the pack.

Though adult lions have no natural predators, evidence suggests that most suffer a violent death caused by humans or other lions. This is particularly true of males as the main defenders of the pack, are more likely to interact aggressively with rival males, in fact, although a male lion can reach an age of fifteen or sixteen if he can not be expelled by other males, most adult males do not live more than ten years. This is the reason why in the wild the average lifespan of lions tend to be significantly lower than that of the lionesses, members of both sexes may be injured or even killed by other lions when two herds conflict with competing territories .

When resting lions perform social functions through a series of behaviors and show well developed expressive movements. They have a set of facial expressions and body postures that are visual gestures, gestures are the most common peaceful rubbing and licking the head of society. Rubbing the head using his nose to caress the forehead, face and neck of another lion, seems to be a kind of greeting as is often observed when an animal has been separated from the rest or after a fight or conflict, males tend to rub other males, while cubs and females rub other females. The Social licking often occur in combination with the friction head are generally mutual and the receptor appears to show pleasure, head and neck are the body parts most commonly lick thing that might be for practical reasons because a lion can not lick these areas by itself.