Substratum
What is substratum?
In Biology, the substratum (or substrate) is the surface on which (or in which) an organism lives.
How does substratum vary?
Substratum varies in many characteristics:
- Type - organic (e.g. mussel shell) or inorganic (e.g. rock)
- Natural (e.g. natural rocky shore) or artificial (e.g. a seawall)
- Particle size - fine sand (<2 mm) to bedrock rock
- Rugosity (surface roughness) - smooth to very rough
- Colour - e.g. white, black, brown
- Aspect/directionality - e.g. north, south, east or west
- Inclination/angle - 0° to 90°
Why is substratum biologically important?
Substratum can provide refuge sites (e.g. rock crevices) from predators and mitigate the effects of environmental stresses (Nybakken & Bertness 2005). Substratum surfaces also provide attachment sites for sessile organisms (e.g. barnacles,mussels) and some motile organisms (e.g. limpets), reducing the risk of dislodgement by wave action. The particle size and rugosity of the substratum can affect the rate of movement of animals. Some animals move slower on sand or on a more complex substratum than on a smooth rock substratum, affecting their predation risk and competitive advantage. The particle size of substratum affects its ability to retain water, nutrients, and oxygen. These properties in turn affect the well-being of plants and animals.
How do animals sense substratum?
Aspects of substratum can be sensed using various sensory organs (see Freeman et al. 2014 and Russell et al. 2019 for more on animal sensory systems):
- Some fishes, crustaceans, and gastropods have eyes that can form images, allowing them to see the substratum.
- Sensory hairs (sensilla or mechanoreceptors) on the surface of the antennae and legs allow some animals to determine the location, shape and texture of the substratum through touch. Other sensory hairs (aesthetascs) are involved in chemoreception, which can also be used in assessing the chemical nature of substratum.
- Some crustaceans (e.g. Gammarus) rely more upon internal receptors (called proprioreceptors) to detect the position and movement of limbs, to assess their environment. Gastropods (e.g. snails) also use internal receptors located on their tentacles and/or foot to assess nearby objects.
- Statocysts provide information on orientation (e.g. is the animal moving up or down a hill).
How do animals respond to variation in substratum?
Intertidal invertebrates may choose and/or move to substrata that provide a benefit (e.g. predator avoidance, protection from extreme temperatures). The rate of movement (see Freeman et al. 2014 for more detail on movement) may also change with differences in substratum characteristics. For example, animals may move more slowly across substrata that make locomotion difficult, or they may move more rapidly over substrata with greater risk of predation or stressful abiotic conditions. Some animals may prefer certain substratum colours over others presumably to improve visual detection of food (e.g. Luchiari et al. 2012).
Key search terms: Substratum · Particle size · Colour · Rugosity · Inclination · Mechanoreceptors · Locomotion
References Cited
Freeman S, Harrington M, Sharp J. 2014. Biological science. 2nd Canadian ed. Toronto: Pearson.
Luchiari AC, Marques AO, Freire FM. 2012. Effects of substrate colour preference on growth of the shrimp Litopenaeus vannamei (Boone, 1931) (Decapoda, Penaeoidea). Crustaceana. 85(7):789–800. DOI: 10.1163/156854012X650232.
Nybakken JW, Bertness MD. 2005. Marine Biology, an ecological approach. 6th ed. Toronto: Benjamin Cummings.
Russell PJ, Hertz PE, McMillan B, Fenton MB, Maxwell D, Haffie T, Milsom B, Nickle T, Ellis S. 2019. Exploring the diversity of life. Biology. 4th Canadian edition. Toronto: Nelson.
Note: Any edition of the above books or other biology textbooks could be useful.
Freeman S, Harrington M, Sharp J. 2014. Biological science. 2nd Canadian ed. Toronto: Pearson.
Luchiari AC, Marques AO, Freire FM. 2012. Effects of substrate colour preference on growth of the shrimp Litopenaeus vannamei (Boone, 1931) (Decapoda, Penaeoidea). Crustaceana. 85(7):789–800. DOI: 10.1163/156854012X650232.
Nybakken JW, Bertness MD. 2005. Marine Biology, an ecological approach. 6th ed. Toronto: Benjamin Cummings.
Russell PJ, Hertz PE, McMillan B, Fenton MB, Maxwell D, Haffie T, Milsom B, Nickle T, Ellis S. 2019. Exploring the diversity of life. Biology. 4th Canadian edition. Toronto: Nelson.
Note: Any edition of the above books or other biology textbooks could be useful.
To learn more:
Firth L, White F, Schofield M, Hanley M, Burrows M, Thompson R, Skov M, Evans A, Moore P, Hawkins S. 2016. Facing the future: the importance of substratum features for ecological engineering of artificial habitats in the rocky intertidal. Marine and Freshwater Research. 67(1):131-143. [accessed 2018 May 30]. https://www.researchgate.net/publication/281767996_Facing_the_future_The_importance_of_substratum_features_for_ecological_engineering_of_artificial_habitats_in_the_rocky_intertidal.
Gedan KB, Bernhardt J, Bertness MD, Leslie HM. 2011. Substrate size mediates thermal stress in the rocky intertidal. Ecology. 92(3):576–582. [accessed 2018 May 30]. https://www.jstor.org/stable/pdf/41151175.pdf?refreqid=excelsior%3A3bc3f9497b4d8cb3eb7d8f8d9fe4f9f4.
Römer H, Tautz J. 1992. Invertebrate auditory receptors. In: Ito F, editor. Comparative aspects of mechanoreceptor systems. Advances in comparative and environmental physiology, Vol 10. Berlin, Heidelberg: Springer. [accessed 2018 May 30]. https://link.springer.com/content/pdf/10.1007%2F978-3-642-76690-9.pdf.
Loke LHL, Todd PA. 2016. Structural complexity and component type increase intertidal biodiversity independently of area. Ecology. 97(2):383–393. [accessed 2018 May 30]. https://esajournals.onlinelibrary.wiley.com/doi/full/10.1890/15-0257.1.
Wieser W. 1959. The effect of grain size on the distribution of small invertebrates inhabiting the beaches of Puget Sound. Limnology and Oceanography. 4(2):181–194. [accessed 2018 May 30]. https://aslopubs.onlinelibrary.wiley.com/doi/abs/10.4319/lo.1959.4.2.0181.
Firth L, White F, Schofield M, Hanley M, Burrows M, Thompson R, Skov M, Evans A, Moore P, Hawkins S. 2016. Facing the future: the importance of substratum features for ecological engineering of artificial habitats in the rocky intertidal. Marine and Freshwater Research. 67(1):131-143. [accessed 2018 May 30]. https://www.researchgate.net/publication/281767996_Facing_the_future_The_importance_of_substratum_features_for_ecological_engineering_of_artificial_habitats_in_the_rocky_intertidal.
Gedan KB, Bernhardt J, Bertness MD, Leslie HM. 2011. Substrate size mediates thermal stress in the rocky intertidal. Ecology. 92(3):576–582. [accessed 2018 May 30]. https://www.jstor.org/stable/pdf/41151175.pdf?refreqid=excelsior%3A3bc3f9497b4d8cb3eb7d8f8d9fe4f9f4.
Römer H, Tautz J. 1992. Invertebrate auditory receptors. In: Ito F, editor. Comparative aspects of mechanoreceptor systems. Advances in comparative and environmental physiology, Vol 10. Berlin, Heidelberg: Springer. [accessed 2018 May 30]. https://link.springer.com/content/pdf/10.1007%2F978-3-642-76690-9.pdf.
Loke LHL, Todd PA. 2016. Structural complexity and component type increase intertidal biodiversity independently of area. Ecology. 97(2):383–393. [accessed 2018 May 30]. https://esajournals.onlinelibrary.wiley.com/doi/full/10.1890/15-0257.1.
Wieser W. 1959. The effect of grain size on the distribution of small invertebrates inhabiting the beaches of Puget Sound. Limnology and Oceanography. 4(2):181–194. [accessed 2018 May 30]. https://aslopubs.onlinelibrary.wiley.com/doi/abs/10.4319/lo.1959.4.2.0181.