Standard Article

Ecology of Storage and Allocation of Resources: Animals

  1. Caroline M Pond

Published Online: 17 OCT 2011

DOI: 10.1002/9780470015902.a0003207.pub2

eLS

eLS

How to Cite

Pond, C. M. 2011. Ecology of Storage and Allocation of Resources: Animals. eLS. .

Author Information

  1. The Open University, Milton Keynes, UK

Publication History

  1. Published Online: 17 OCT 2011

Abstract

Most organisms store lipids and/or carbohydrates for energy production during fasting. Lipids store much more energy per unit mass. Long-chain fatty acids are absorbed and stored almost unaltered, so serve as indicators of natural diets and food chains. Vertebrates and higher arthropods have tissues specialised for lipid storage and management. Adipocytes are 40–85% triacylglycerols and occur in various intra-abdominal and superficial sites in all tetrapods and some fish. Some mammalian adipose depots have site-specific properties specialised to local, paracrine interactions with adjacent cells and tissues. In mammals, adipocyte volume is determined by anatomical location, body size and natural diet as well as fatness. The anatomical patterns of relative sizes of adipocytes are similar in all terrestrial mammals but species differ in the relative abundance of adipocytes in each depot. The chemical compositions of storage molecules are adapted to the ecological processes they serve, including migration, hibernation, lactation or unpredictable food supply. Storage of energy and other materials is essential to many aspects of animals' ecology. Adipose tissue can reach 50% body mass before migration or breeding fasts with superficial depots expanding most, especially in large vertebrates.

Key Concepts:

  • Storage is essential unless nutrients are continuously available.

  • Storage materials must minimise weight, volume and toxicity; some vitamins and minerals are too toxic to be stored in more than small quantities.

  • In animals, glycogen and acylglycerols can be safely stored in large quantities and metabolised to produce energy and/or tissues.

  • Much more energy can be stored as lipid than as glycogen, though the latter is more quickly mobilised.

  • The chemical composition of storage lipids is adapted to body temperature and the ecological processes that they support. Triacylglycerols of cold-adapted poikilotherms and hibernating mammals have more unsaturated fatty acids than those of homeotherms.

  • Some migratory birds maximises energy density and efficient mobilisation of the storage lipids during prolonged flight by adaptive desaturation.

  • Specialised lipid storage tissues include the arthropod fat body and vertebrate adipose tissue that sequesters large quantities of triacylglycerols.

  • Vertebrate adipocytes are nearly spherical cells, 0.01–4 nL in volume, specialised to take up, hold and release storage lipids and to the regulation of appetite and metabolism.

  • In mammals, the mean volume of adipocytes is determined by anatomical location, body size and natural diet as well as by fatness.

  • Some mammalian adipocytes have site-specific properties specialised to paracrine interactions.

Keywords:

  • adipose tissue;
  • adipocyte;
  • fatty acid;
  • triacylglycerol;
  • hibernation;
  • migration;
  • fat indices;
  • secondary compound;
  • lymph node