INNATE BEHAVIOR IN PLANTS AND PROTISTS

Innate Behavior Any form of behavior that has not been learned is innate behavior Most innate behavior aids survival and reproduction. Innate behavior results from impulse pathways built into the nervous system. Instruction for the impulse pathways are carried in the DNA of the individual. These instructions are all the same for given species.

Innate Behavior They are passed from parent to offspring as an inherited trait. An organism cannot “choose” to perform an innate behavior-it occurs automatically. Innate behavior is found in most organism. In simple organisms, such as the paramecium, sea anemone and flatworm, all behavior is almost entirely innate. In more complex animals, only part of the behavior is innate. The remainder is learned behavior

Innate Behavior in Plants Plants also have inborn responses to stimuli. In plants , growth toward or away form stimuli is called tropism. This growth may involve the roots, stems or leaves. Environmental factors, such as light, gravity, water, heat and chemicals, act as stimuli for a tropism It is controlled by hormones

Phototropism

Phototropism Geotropism

Tropism, negative response to gravity Onion (Allium cepa)

Rapid movements such as closing leaves involve changes in the turgor pressure in cells

Innate Behavior in Protists One characteristic of cells is their sensitivity to stimuli. The ameba and the paramecium do not have a nervous system, but they are able to respond to environmental changes. Any movement by a simple animal or a protists toward or away from a particular stimulus is called a taxis.

Chemotaxis:movement or growth of an organism in response to changing concentration of a chemical stimulus, often in relation to food or for mating [Attraction of lesion nematodes (Pratylenchus sp.) near the root hair zone]

REFLEXES As an animal develops, its neurons develop connections that form a system. For the most part, once the system is formed, neurons do not change their connections with other nerve. These fixed pathways in the nervous system are the basis for a type of innate behavior called reflex

A reflex involves a receptor (sense organ) that detects stimuli and an effector (muscle or gland) that produces a reaction. Nerve cells connecting the receptor and effector through the spine or lower brain complete the nerve pathway, which is called the reflex arc. Reflex actions are simple, quick, and automatic because they do not require control by the upper brain

You can respond to a stimulus faster if you do not have to process information in your brain and decide what to do. If you touch a hot object, a reflex response causes you to pull back your hand quickly, before you are consciously aware of the pain. Thus reflexes help an organisms to avoid injury by allowing it to react quickly to environmental changes.

A flatworm subjected to electric shock automatically contracts If a frog toe’s is pinched, the leg is always drawn away

The behavior of preying mantis is an example. When a fly or other insect appears in the mantis’s field of vision, the mantis turns its head to face the insect. This is the first reflex. Then, the mantis orients its body in the same direction as the head-the second reflex. If the fly is close enough, the mantis instantly strikes, grasping the fly with its front legs.The strike- the third reflex-takes only a fraction of a second.

INSTINCTS Some animal behavior patterns involve a complicated set of unlearned activities that occur in response to a stimulus or series of stimuli. Such a complex, inherited behavior sequence is called an instinct. While instinct are quite complicated, they do not have to learned and are performed automatically. However, an organism performing an instinctive behavior can be consciously aware of what it is doing. In contrast, a taxis and a reflex are simpler behaviors that are performed unconsciously.

INSTINCTS Instincts usually are associated with either inidividual survival or species survival. They often involve activities related to feeding, defense, or reproduction. Instincts provide an animal with ready made “answers” to its problems of survival because no time is required to learn a response. This is important for an animal with a short life span

EXAMPLES FOR INSTINCTS The migration of salmon up to same river in which they were hatched.

The communication “dances” of bees

The construction of a hanging nest by the Baltimore oriole

A spider’s construction of its intricate web, for example is an instinct. In fact the structure of its web can identify a spider as easily as its anatomy.There are four basic types of webs.

Courtship ritual

The june beetle larva shuns light The june beetle larva shuns light. However, adult june beetles are attracted to light, often scraping loudly against the screens of lighted windows

Without being taught, the caterpillar of the gypsy moth climbs upward when hungry. Just before it enters the pupa stage, it spins a particular typr of cocoon in a series of steps performed only once in it life.

The male sunfish scoops out a shallow, saucerlike nest in the bottom sediments of a pond or lake. He removes all the pebbles, leaving a layer sand. After the female lays her eggs in the nest and they are fertilized, the eggs adhere to the sand. Only the male cares for the eggs. He fans the eggs with his tail and drives away predators until the eggs hatch.

The reproductive behavior of the three-spined stickleback is composed of a sequence of ordered stimuli and responses. After establishing a territory, the male builds a nest. If an egg-laden female enters his territory, the male performs zigzag courtship dance. The female responds by swimming toward the male. The male then swims toward the nest and pointed to nest Female enters the nest Male trembles and nudges female Female lays eggs in the nest Female leaves the nest Male enters the nest and fertilizes eggs.

HORMONAL CONTROL OF INSTINCT Many physiological stimuli, which are related to an organism’s metabolism, can trigger instincts. Often, the animal responds to these stimuli with instinctive behavior that tends to restore homeostasis. Reproductive or sex hormones are the physiological stimuli that lead to courtship, mating, production of milk and care of young. The hypothalamus and pituitary may also control reproductive behavior and parental control of offspring.

The hormone prolactin influences parental feeding in doves The hormone prolactin influences parental feeding in doves.The first few days after hatching, the young are fed pigeon milk, an off-white substance which resembles fine curd cottage cheese and has a very pungent odour. The epithelial lining of the crop of the birds thickens and then sloughs off to form pigeon milk. The young birds place their bills far up into the throats of the adults, and swallow as their mouths fill. Within a few days, the young begin to receive grain mixed with the pigeon milk. Hormones may also influence behavior by acting on the central nervous system. Female canaries, unlike males, usually do not sing. But, if a pellet of male sex hormone is placed under the skin of a female, she will sing a typical canary song until all the hormone is metabolized

Sometimes, a visual stimulus can trigger the hypothalamus Sometimes, a visual stimulus can trigger the hypothalamus. If a female ring dove sees a male, the visual image stimulates cells in her hypothalamus, which activates her pituitary gland. Hormones from the pituitary gland cause the growth of the ovaries and secretion of the female hormone estrogen. The female then lays egg. Normally, the hormone level of a female ring dove that does not see a male remains low. A female, however, can lay eggs without seeing a male if she is given an injection of hormones.

Once internal conditions have been altered by hormones, the animals responds to external stimuli that do not ordinarily affect it. Specific environmental stimuli can then start various forms of reproductive behavior. After hormones have caused the male three-spined stickle back to establish a territory and build a nest, he guards his territory against the intrusion of other males. When other males approach, he becomesaggressive and drives them away. During the mating period, the belly of a male becomes red. It is the red color on th ebelly of another male that stimulates the aggressive behavior.