Heterotrophic Nutrition
Organisms that aren't food producers must be food consumers. This method of nutrition is described as heterotrophic (eating others).
Consumers include: predators, parasites, scavengers, decomposers and some green plants (e.g. sundews, Venus flytrap, pitcher plants).
The food sources may be all or any of: plants, animals, fungi or bacteria; either living or dead.
The advantages of the heterotrophic method of nutrition are: the food usually contains all the appropriate chemicals needed by the consumer
"feeding" is not restricted to daylight hours.
The disadvantages are:
1) The consumer has to find food by one of the following: active hunting - requiring well developed systems: a) locomotion and b) sensory and nervous systems. b) passive accumulation - e.g. filter feeding by sedentary animals. c) passive dispersal onto a suitable food source, e.g. fungal and bacterial spores.
May have to overcome prey defences (e.g. spines, prickles, noxious chemicals) and therefore might need weapons of attack or immunity to these chemical defences.
The food has to be made usable by the consumer by a process of digestion. Material that is indigestible will have to be voided.
Foods are usually dead or alive body parts and generally consist of large, complex organic molecules that need breaking down to smaller chemically simpler forms. small, simple organic and inorganic molecules and ions which just need to be dissolved. other materials which are usually not usable (e.g. lignin, wax, chitin) and which must be discarded.
The amount of physical and/or chemical breakdown necessary depends on the size and composition of the food; as a consequence the nature of the digestive systems will vary somewhat according to the nature of the food.
Digestion occurs externally in decomposers (fungi, bacteria) and carnivorous plants. These organisms secrete digestive enzymes onto the food on/or through which they are growing (bacteria, fungi) or which they
Consumers include: predators, parasites, scavengers, decomposers and some green plants (e.g. sundews, Venus flytrap, pitcher plants).
The food sources may be all or any of: plants, animals, fungi or bacteria; either living or dead.
The advantages of the heterotrophic method of nutrition are: the food usually contains all the appropriate chemicals needed by the consumer
"feeding" is not restricted to daylight hours.
The disadvantages are:
1) The consumer has to find food by one of the following: active hunting - requiring well developed systems: a) locomotion and b) sensory and nervous systems. b) passive accumulation - e.g. filter feeding by sedentary animals. c) passive dispersal onto a suitable food source, e.g. fungal and bacterial spores.
May have to overcome prey defences (e.g. spines, prickles, noxious chemicals) and therefore might need weapons of attack or immunity to these chemical defences.
The food has to be made usable by the consumer by a process of digestion. Material that is indigestible will have to be voided.
Foods are usually dead or alive body parts and generally consist of large, complex organic molecules that need breaking down to smaller chemically simpler forms. small, simple organic and inorganic molecules and ions which just need to be dissolved. other materials which are usually not usable (e.g. lignin, wax, chitin) and which must be discarded.
The amount of physical and/or chemical breakdown necessary depends on the size and composition of the food; as a consequence the nature of the digestive systems will vary somewhat according to the nature of the food.
Digestion occurs externally in decomposers (fungi, bacteria) and carnivorous plants. These organisms secrete digestive enzymes onto the food on/or through which they are growing (bacteria, fungi) or which they