AH BiologyEnvironmental Biology

Homeostasisand

Estuarine Animals

Estuaries – a stressed habitat

Tidal movements results in:

Variable abiotic factors:• Salinity• Temperature• Oxygen• Density

Organisms can respond to change by:

http://vimeo.com/4997994

Osmoconformers

• Their blood concentration varies with the environment, ie they passively tolerate changes in salinity

• eg jellyfish, squid

Osmoregulators

• 1. Hyper/Iso Regulation

• When the conc. is low the organism keeps its internal conc. hypertonic (less water) to the external conc. As the salt concentration rises it reaches a point where it can no longer control and becomes isotonic.

• eg Corophium

• 2. Hyper/Hypo Regulation

• At the freshest conc. the organism is hypertonic but as conc. increases it becomes hypotonic.

• eg prawn

How do they do it?

• Contractile vacuoles• Chloride secretory

cells, etc