Welcome to
Unit 2 Biology

Organisms and their

Environment

Area of Study 1 –
Adaptations of Organisms

Chapter 9

Habitats, environment and survival.

Key Knowledge

Develop a knowledge and understanding of habitats and the environments that exist in them.

Identify major factors that produce the environments of various habitats and distinguish between biotic and abiotic factors.

Give examples of structural adaptations that equip organisms for survival under particular environmental conditions.

Explore technologies used to record environmental factors and track distribution of species within their habitat.

What is a habitat?

The location or place where an organism lives at any given time is known as its habitat.

The habitats of different kinds of organisms vary greatly.

Many habitats can be described in general terms as being

- Terrestrial (e.g. deserts, grasslands, forests etc) or

- Aquatic, which includes freshwater, marine and estuarine.

Microhabitats

In reality, many organisms share one habitat.

The way that they accomplish this, without becoming overcrowded is to occupy their own individual microhabitat.

A microhabitat is a more localised or specialised part of a general habitat.

For example, in a freshwater pond, some organisms may occupy the soft sediment at the bottom, while others may live among the aquatic plants. These are two different of many microhabitats

More on habitats

The habitat provides the resources that are needed for the life of a particular organism.

For a typical animal, these include water, food, shelter, nesting and breeding sites.

Habitats are not uniform.

For example animal may feed in one part of a habitat, while it nests in another part of the habitat, and finds water in yet another part.

Range: the distribution of habitats

The geographic area that encloses all the habitats where the species lives denotes the range or distribution map of the species.

Over time, the range of any species may increase or decrease, depending on its needs.

Many of our native Australian species have a shrinking range, due to increased human population or introduced species.

Conversely, the range of many introduced species is increasing.

Migration

There are often reasons for animals to move between habitats.

Animals that do this are said to be migratory.

Migrations are typically associated with access to food resources or breeding sites or to movement from unfavorable seasonal conditions, such as moving from extreme cold.

Species with an annual migration of their life cycle include:

- short-tailed shearwaters or muttonbirds

- humpback whales

Species with a once a lifetime migration in their life cycle include:

- short-finned eels

- bogong moths

Diapause

Some animals cope with seasonal lows using the state of diapause.

This is where an animal moves into ‘energy control mode’ during times of the year that are unfavourable.

This usually includes being in a non-feeding low energy state.

This stage is similar to that known as hibernation.

Technology

How does technology fit into habitats???

It is an important tool in the study of habitats, particularly those that cover large areas.

It is more accurate than the old fashioned one person in the field with a notebook.

Different uses for technology

Monitoring vegetation is large scale habitats

Conventional techniques, such as aerial photography is useful in some ways, but has the downfall of being unable to distinguish different species of plants which may be crucial to the survival of a certain species.

The use of remote sensing on an orbiting satellite, such as Landsat is able to achieve this by detecting ‘signatures’ present in the vegetation of concern.

Monitoring animal movements within habitats

Some animals move over very large distances within their habitat.

Several radio tracking or telemetry techniques are in current use, but these devices are generally restricted to larger animals with sufficient size to carry the tracking device.

The oldest technique for tracking terrestrial animals is very high frequency (VHF) radio tracking, that was introduced in 1963. This involved a device being built into a collar.

Later, satellite tracking became available. This technology enables animals to be tracked both across large areas of land and in the ocean. Unlike VHF tracking, satellite tracking does not require people to be in the tracking area.

A relatively new form of tracking, called a pop off archival tag (PAT), which is Used for aquatic animals.

This type of tag not only provides migratory information, but also information on the environment.

These tags are programmed to collect data every few minutes over a given period of time. At the end of that time, the tag detaches, or ‘pops off’ the animal and floats to the surface.

Who lives in a habitat?

Members of one species do not live in isolation in a habitat.

Members of the different species that share one habitat form the living community of the habitat.

What is a niche?

The term ‘niche’ refers to the ‘way of life of a species’. Some other short definitions of a niche include:

- the role or profession of a species in a community

- the way of life of an organism

- the status or role of an organism in its habitat.

The many species living in a biological community have different ways of lives or niches.

For each animal species, a description of its niche might include where it lives and feeds, what it eats, when it feeds and the environmental conditions it tolerates.

Structural features equip various species to occupy different niches in a habitat e.g. beak length.

Niche overlap

Because they are not in direct competition for the same food and space resources at the same time, different species in a community in a natural habitat typically have either zero or a low degree of niche overlap.

In general, two or more different species cannot occupy the same niche in the same community for an extended period of time. They will be in direct competition which could possibly result in a depletion of resources, which could be ultimately detrimental to both species.

Environment

The physical, chemical and biological conditions that exist in the habitat make up the environment.

An environment may also be described as:

A collective term for the conditions in which an organism lives

The sum total of external influences acting on an organism

The external surroundings in which an organism lives and which are influenced by abiotic and biotic factors.

Environmental factors

The various factors that produce the particular conditions in a habitat are called environmental factors.

Biotic or living factors relate to other living organisms in the environment and include factors such as the presence of predators, parasites and competition between members of one species.

Abiotic are non living factors relating to aspects of soil, water, light, shelter, temperature etc.

Comparing air and sea

Air and sea water have very different properties, and in turn, terrestrial and marine environments have very different environments.

These differences directly influence the animals that have evolved in each of these environments, resulting in significant structural and physiological differences between terrestrial and marine organisms.

Describing environmental conditions

An environment can be described in qualitative terms, such as ‘warm and humid’ where ‘warm’ refers to the air temperature and ‘humid’ refers to the water vapour content of the air.

An environment may also be described in quantitative terms where a numeric value is stated, such as, ‘the air temperature is 23°c’.

When scientists measure environmental factors in a habitat, they usually express their findings in quantitative term. Some of the devices are shown on the next slide.

Tolerance range

The distribution map of each species is affected by environmental factors. Every organism has a tolerance range for environmental factors, such as temperature, desiccation (drying out), oxygen concentration, light exposure and so on.

A tolerance limit identifies the range in which an animal can survive that particular condition.

If an environmental factor has a value above or below the animals tolerance limits, that organism will not survive if it cannot escape.

Tolerance ranges differ for species and are influenced by structural, physiological and behavioral factors of an organism.

See if you can think of and explain one example of each….

Tolerance range

Who survives where?

The kinds of organisms found in various habitats are determined by their ability to survive in the prevailing environmental conditions.

Organisms have both upper and lower limits.

Any condition which approaches or exceeds the limits of tolerance for an organism is said to be a limiting factor for that organism.

Additional notes