Responding to the Environment Animal Survival See pages 138 – 141 Torrance

Responding to the Environment Animals and plants are subject to Environmental Stimuli. Animals and plants are subject to Environmental Stimuli. Temperature changes, pH changes, changes in light intensity, chemicals,food are all examples of environmental stimuli Temperature changes, pH changes, changes in light intensity, chemicals,food are all examples of environmental stimuli A living organism will either move towards or away from a stimulus A living organism will either move towards or away from a stimulus

Responding to the Environment OrganismStimulusResponse Survival value Woodlouselight Moves away Keeps skin moist and avoids predators Paramecium Weak acid Moves toward Paramecium feeds on bacteria that live in acid conditions Blow fly maggots light Moves away Dark places provide food,water and shelter

Responding to the Environment A response to an environmental stimulus is of survival value to an organism e.g. Avoid predators, prevent drying out etc. A response to an environmental stimulus is of survival value to an organism e.g. Avoid predators, prevent drying out etc. A choice chamber can be used to see how a stimulus affects a living organism A choice chamber can be used to see how a stimulus affects a living organism In a choice chamber, organisms are faced with two different environments. They will congregate in the environment which suits them best. This allows us to determine the most suitable conditions for their survival. In a choice chamber, organisms are faced with two different environments. They will congregate in the environment which suits them best. This allows us to determine the most suitable conditions for their survival.

Woodlice prefer moist conditions – it prevents them drying out. They move quickly when in dry conditions to increase their chance of leaving the unfavourable environment and finding a more suitable one. They move more slowly or stop when it is moist, increasing their chance of staying in the favourable environment. E.g. WetDry woodlice Choice chamber

How do woodlice respond to light? – ( An example of a stimulus and response) Woodlice respond to light. Woodlice respond to light. The following experiment is set up to find out if The following experiment is set up to find out if A) they move towards the light A) they move towards the lightor B) they move away from the light B) they move away from the light

How to set up a choice chamber A choice chamber (½ black and ½ light) is collected. A choice chamber (½ black and ½ light) is collected. A piece of gauze is placed inside as a platform for the woodlice to walk on. A piece of gauze is placed inside as a platform for the woodlice to walk on. 10 woodlice are added to the chamber at the centre hole 10 woodlice are added to the chamber at the centre hole It is left for 10 minutes and every 2 minutes the number of woodlice in each side are counted. It is left for 10 minutes and every 2 minutes the number of woodlice in each side are counted.

Black cover (dark side) gauze Light side Time (mins)

Results Time (min) Time (min) Number of organisms on the light side of the chamber Number of organisms on the dark side of the chamber

Conclusion The organism responded to the light stimuli by moving away from it. The organism responded to the light stimuli by moving away from it. Why? Why? They avoid being seen and eaten by predators They avoid drying out in sunlight

Responding to the Environment Rhythmical Behaviour This is a type of behaviour repeated at regular intervals This is a type of behaviour repeated at regular intervals It is usually triggered by an external stimulus e.g. daylength or temperature It is usually triggered by an external stimulus e.g. daylength or temperature

Responding to the Environment Type of Rhythm Animal Rhythmical behaviour External trigger stimulus Significance Tidal Fiddler crab Active at high tide inactive at low tide Movement of tide caused by the moon Enables crab to find food Circadian(daily)Cockroach Active at night Onset of darkness Can feed unseen by predators AnnualSwallow Migrates to warmer climates Onset of shorter day lengths Escapes cold temperatures and food shortage in winter

Daily Changes These changes occur every 24 hours. These changes occur every 24 hours. The most obvious is light and dark. The most obvious is light and dark. Many animals have adapted their behaviour to being active and feeding during the day (DIURNAL animals) whereas others are active at night (NOCTURNAL animals). Many animals have adapted their behaviour to being active and feeding during the day (DIURNAL animals) whereas others are active at night (NOCTURNAL animals).

Diurnal Animals

Nocturnal Animals

Tidal Changes Most seashore animals show some adaptations to the tidal movement. Most seashore animals show some adaptations to the tidal movement. Tidal movement occurs twice daily – i.e. at high tide and low tide. Tidal movement occurs twice daily – i.e. at high tide and low tide.

Shore Crab Rhythmical Behaviour in Shore Crabs

Daily tidal changes bring about a rhythmical behaviour pattern in many seashore animals. Daily tidal changes bring about a rhythmical behaviour pattern in many seashore animals. The shore crab regulates its period of activity to coincide with the movement of the tide – active at high tide The shore crab regulates its period of activity to coincide with the movement of the tide – active at high tide The shore crab is found in rock pools. The shore crab is found in rock pools.

Advantages of daily rhythmical behaviour Avoids predators Avoids predators More food available when active More food available when active

Annual Changes Over the period of a year there are seasonal changes. Over the period of a year there are seasonal changes. During summer the number of daylight hours (daylength) is greater than in winter. During summer the number of daylight hours (daylength) is greater than in winter.

Annual Rhythm Rhythmical behaviour occurs in response to regular changes in the environment. Rhythmical behaviour occurs in response to regular changes in the environment. In animals, environmental stimuli like changing daylength, light and dark, etc. can set off certain responses In animals, environmental stimuli like changing daylength, light and dark, etc. can set off certain responses Annual rhythmical behaviour occurs is repeated every year. Annual rhythmical behaviour occurs is repeated every year. Migration, hibernation and courtship are examples of annual rhythmical behaviour brought about by changes in daylength. Migration, hibernation and courtship are examples of annual rhythmical behaviour brought about by changes in daylength.

Courtship

Most birds produce their eggs soon after mating, and hatching occurs a few weeks later. Most birds produce their eggs soon after mating, and hatching occurs a few weeks later. In contrast, red deer don’t have their young until 6 months after mating. In contrast, red deer don’t have their young until 6 months after mating.

Advantages of Courtship Courtship behaviour ensures that reproduction occurs at a time of year that makes sure that young are born when: Courtship behaviour ensures that reproduction occurs at a time of year that makes sure that young are born when: Weather conditions are good and food is plentiful. Weather conditions are good and food is plentiful. This means the young have a better chance of survival. This means the young have a better chance of survival.

Hibernation During severe winter conditions, food is in short supply. During severe winter conditions, food is in short supply. The more an animal moves around looking for food, the more energy it uses. The more an animal moves around looking for food, the more energy it uses. During severe winters the animal may die. During severe winters the animal may die.

During hibernation, the animal goes into a type of “sleep”.

Before they go into hibernation the animals must increase their feeding to build up reserves of food which can be used over the period of hibernation. Before they go into hibernation the animals must increase their feeding to build up reserves of food which can be used over the period of hibernation. Hedgehogs, bears and squirrels are examples of hibernating mammals.

Advantages of Hibernation To overcome this problem of energy loss and to increase the chance of survival during the winter, some animals hibernate. To overcome this problem of energy loss and to increase the chance of survival during the winter, some animals hibernate. The animal reduces its rate of using energy by stopping movement and reducing it’s body temperature. The animal reduces its rate of using energy by stopping movement and reducing it’s body temperature.

Migration Migration is an annual rhythm Migration is an annual rhythm Animals migrate to places where there is more food Animals migrate to places where there is more food Swallows, salmon and buffalo migrate Swallows, salmon and buffalo migrate

Advantages of migration behaviour Avoids food shortages Avoids food shortages Avoids harsh winters Avoids harsh winters Allows longer days for feeding Allows longer days for feeding