80 likes | 93 Views
Maintaining Water Balance - Animals. Chapter 22. Adaptation & Water Balance. Adaptations allow living things to be well suited to their environment Can be structural , physiological or behavioural Water balance: - some animals’ cells are isotonic to their environment e.g. jellyfish
E N D
Maintaining Water Balance - Animals Chapter 22
Adaptation & Water Balance • Adaptations allow living things to be well suited to their environment • Can be structural, physiological or behavioural • Water balance: • - some animals’ cells are isotonic to their environment e.g. jellyfish • - they have no need to regulate their water balance • - most aquatic animals have cells that are hyper or hypotonic to their environment • - they often have adaptations that allow them to regulate their water (and ion) concentrations
Osmoregulation - freshwater fish - Mouth & gill membranes are selectively permeable • - constant inflow of water by osmosis • - excess must be removed • Adpatations include: • - many large glomeruli – allows high filtration rate • - kidney tubules very efficient at reabsorbtion • - large volume of dilute urine produced • - gills have chloride secretory cells – salt absorbed from water (needs active transport)
Osmoregulation – saltwater fish • Water continually lost through gills • Several adaptations help • - Sea water is drunk to replace loss • - Kidney has a few small glomeruli – low filtration rate • - Small volume of urine produced • - Waste converted to non-toxic form • - Chloride secretory cells work in reverse (salt excreted)
Adaptations in migratory fish • Fish that spend time in fresh and salt water e.g. Atlantic salmon • Salmon eggs laid in river bed • Salmon hatches & develops into a smolt – migrates downstream • Linger in estuaries to acclimatise to salt water • Leave river and enter seas • Feed off Greenland coast for 1-6 years • Then migrate back, developing reproductive ability • Re-acclimatises to fresh water in estuaries • Hormones likely adapt osmoregulation systems
Water conservation in desert mammals • Have to practice water conservation • Obtain water from food e.g. seeds for kangaroo rats • Physiological Adaptations • Rat’s mouth & nose is dry – water not lost during breathing • Blood has high level of ADH • Kidney tubules have very long loops of Henle • Large intestine very effective at reabsorbing water • Animal never sweats • Behavioural Adaptations • Animal very inactive & burrowed underground during the day • Active at night – forages for food