Title: Essential Features of Animal Life Living organisms share seven biological systems that enable them to sustain life: - Musculoskeletal system that provides their form and their ability to move
- Developmental system that enables it to grow from its birth form to adult form
- Digestive system that enables them to consume and process food needed to produce the energy to grow and to move
- Excretory system to ensure the remove of waste from the digestive and respiratory intake (this can include regurgitated pellets or fluids)
- Respiratory system to enable them to take in oxygen to generate body heat although in ‘cold blooded’ creatures this needs to encompass the absorption of extra heat direct from the outside environment
- Reproductive system to enable them to prolong the longevity of their genes into subsequent generations
- Sensory and nervous system to enable them to be aware of their environment and to respond to outside stimuli
To remember this use of the acronym ‘MERRING’ may prove useful (movement, excretion, respiration, reproduction, irritability, nutrition and growth). These seven biological systems generate characteristics that are both helpful to the nature watcher (+), as well as some that are disadvantageous (-), when trying to identify a creature in the field. Movement - Can reveal presence by the detection movement (+)
- Can conceal presence by moving away (-)
- Can reveal presence by the detection of tracks (+)
- View can improve or degrade as creature moves closer or further away (+/-)
- Some creatures may be identified purely by the way they move (+)
- Some creatures make a unique noise when they move(+)
- Some species move together in herds or flocks or form swarms (+)
- May be seen at one site today but when you go to see it tomorrow it may have long been gone (-)
- May restrict access to seeing the creature to certain times a year (migration) (+/-)
Excretion - Traces of excrement can reveal the location of a nest or roost (+)
- Traces of excrement can reveal a favoured perch or resting place (+)
- Some creatures can be identified by the uniqueness of their excrement (+)
- Some creatures use excrement as a means of defence that can be unpleasant (-)
Respiration - Water based animals often to surface to breath which reveals not only their presence but often their species (+)
- Cold blooded animals need to be still and absorb heat which can make them easier to find and view (+)
- Cold blooded animals are susceptible to the weather and can be hard to find in some weather conditions (-)
Reproduction - Courting and breeding often creates unique behaviour (singing on a territory, ritual display, distraction techniques) (+)
- A display or nest site can become a focus for observation once located (+)
- Some species take on special external characteristics (such as breeding plumage) during the breeding season which make them easier to identify (+)
- Some species are only here to breed (migration) (+)
- Some species will only be found in preferred habitat for breeding which provides a key as to where to look (+)
- Some insects use only certain food plants to lay their eggs on (+)
- Eggs, when found, are often unique in appearance to a species (+)
- Sexes can differ in appearance or plumage so two identities may need to be understood (-)
- This can be further complicated by a change in appearance or plumage in the breeding season making even more variation within the same species (-)
- Some species can become very secretive and protective during the breeding season (-)
- Some species will desert their nest or young of disturbed so care needs to be taken to avoid this (-)
- Male Blackbirds (and many other birds) sing from a favoured spot in their territory
Irritability - Sensory organs can give unique facial characteristics that aid identification (+)
- Some are adapted of be most effective at certain times of day or night (+/-)
- Alarm calls when disturbed can reveal presence (+)
- Some creatures are attracted by certain external stimuli (+)
- Can see, hear or smell observer long before observer sees the creature (-)
- Some animals can detect vibrations or even changes in air pressure (-)
- Special attention is needed to observe some species (hides, clothing, field crafts, equipment) (+/-)
Nutrition - Hunting and foraging behaviour can be unique in some species (+)
- Often creatures can be stationery and preoccupied when feeding (+)
- Finding the food source can help find the creature
- Variation in food supplies can lead to an influx of species not usually seen or outward movement of others (+/-)
- Fondness for certain foods can be used to attract creatures (+)
- Some creatures use venom to kill their prey and can be dangerous (-)
- Some creatures hibernate during times of food shortage (-)
- Some prefer habitat that is remote or hostile to mankind (-)
- Some creatures are parasitic and can only be found on their host (+)
Growth - Creatures grow in to unique shapes and appearances (+)
- Some creatures have different stages in their life cycle that are easier to locate or identify than others stages (+/-)
- Young may have restricted ability to move and will be more easily watched (+)
- Some stages of growth are limited to certain times a year which and the time seen can be diagnostic (+/-)
- There is often a variation in appearance at different stages of growth giving identification difficulties (-)
- The young of some species are well camouflaged for protection from predators (-)
- Some animals shed skin as they grow or shed casing as they move to a new life stage (+)
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