Interactions with the Environment

2 major responses to the environment by organisms:

In regulators the internal environment is maintained at a set point despite changes in the external environment

Regulation

In conformers the internal environment fluctuates with the external environment

Conformation

Conformers

are animals whose body temperature fluctuates with their surroundings.

Often called ectotherms these include snakes, lizards and marine fish.

is being isosmotic to the surrounding environment.

Their body fluids will be isotonic to their surroundings.

These includes crabs, shrimps, jelly fish and other marine organisms.

Osmoconformation

Poikilotherms

Conformers

Features

May have more energy available for growth relatively speaking compared to regulators.

Often have reduced energy needs compared to regulators.

Activities limited by conforming state.

Limited in their geographical range.

Regulators

are animals that can maintain their body temperature independently of the environmental temperature.

These organisms are called endotherms and the heat energy comes from metabolic processes.

These include mammals and birds.

Homeotherms

Osmoregulation

is the ability of organisms to maintain a constant water balance in their cells

These include mammals, marine and freshwater fish.

Regulators

Features

Can be active in a wide range of environments and inhabit a wider range of geographical areas than conformers.

Require considerably more energy when compared to conformers beyond that needed for growth and repair, so they will need to feed more often.

Use a lot of energy maintaining their internal environment.

Homeostasis principles

Osmoregulation

The Survival strategies of Dormancy

Organism must have a resistant stage and synchronised life cycle to environmental conditions.

Dormancy occurs in plant seeds, temperate and arctic mammals.

Metabolic processes are slowed or suspended until conditions become more favourable.

Development of the organism is suspended due to unfavourable conditions.

Synchronisation

Dormancy happens as a result of unfavourable conditions. Can result in substantial loses but can mean better utilisation of resources.

Consequential strategy

Dormancy occurs before the unfavourable conditions, triggered by a stimulus like daylength or temperature.

Predictive strategy

Types of Dormancy

Resting Spores

AestivationHibernation

Diapause

Torpor

Torpor

Reduction of body temperature compared to external temperature e.g. bats, mice and humming birds.

Diapause

Dormancy allowing them to suspend development between autumn and spring.

E.g. deer delay implantation so young are born in spring.

E.g. insects pupate from Autumn to spring

This is a predictive strategy.

Hibernation - escaping cold weather and lack of food.

Animals prepare by building up fat store before and

slow metabolism during (heart rate).

This can be predictive or consequential.

Aestivation - occurs in response to hot, dry conditions. Snails seal shells if it is dry, lungfish burrow into mud.

This is a consequential strategy.

Resting Spores - a hard case is formed around seed or spore.

Can remain viable for long periods of time.

This is a consequential strategy.

Life cycles

Organisms have a variety of life cycles.

Survival strategies exist to ensure organisms pass on their genetic information to their offspring.

Reproduction can either be once or many times depending on species.

Tapeworm lifecycle