Challenges and Adaptations. Terrestrial. Sea water. Fresh water

Transcription

1 Environmental physiology Challenges and Adaptations Terrestrial Sea water Fresh water

2 Marine life Sea: 70% surface of planet. Most phyla of animals live in the sea Ocean all connected: relative constant chemical composition Currents mix the waters Constant conditions of salinity, temperature and gas availability Primary productivity is high where cold and warm currents mix

3 Marine life life Different ecological niches Pelagic: floaters, drifters, swimmers Bentos: bottom dwellers Pelagic organisms Plankton- floaters and drifters Nekton - free swimmers

4 Marine life: coral reefs and kelp forests Only in relatively shallow seas where there are areas of reef or kelp forest we find a real habitat complexity to promote very high diversity.

5 Marine life: kelp forests Macroalgae: seaweed

6 Marine life life

7 Plankton Plankton Wanderer or drifter- includes plants, animals and bacteria Range in size from submicroscopic (bacteria) up to large jelly fish Can not purposefully move horizontally in the water column. Can adjust vertical position- gives them some control Often have buoyancy mechanism to keep from sinking- float chambers, spines A. Phytoplankton primary producers, plants (diatoms, dinoflagellates, coccolithophores) B. Zooplankton Zooplankton- animals (herbivores and carnivores)- heterotrophs

8 Nekton Swimmers: vertebrates- fish, marine mammals one group of invertebrates - squid, octopus

9 Bentos Bottom dwellers- can be attached to the bottom or free moving

10 Feeding in the ocean Autotrophs: Primary productivity: microalgae-macroalgae Heterotrophs: 1. Filterers: cilia, flagellae, gills 2. Predators: nektonic, Benthic: filter, scavengers, specialized predators

11 Nutrition: corals of warm waters need light because they are symbiotic with algae Symbioses with autotrophs

12 Metabolism Relative low metabolism in marine vertebrate and invertebrate Metabolism in marine animals: low cost of swimming

13 Sea Temperature and thermoregulation

14 Movement and flotation Methods to increase buoyancy Movement Water more dense and viscous that air- more difficult to move through Swim with snake-like motions, requires a lot of energy Torpedo shape- relatively rigid body with hinged tail. More efficient shape.

15 Movement : Blood supply to red swimming muscles

16 Respiration in the sea The physical properties of water affect respiration Water more dense: more energy to move it (ventilation) A water-breathing animals must work much harder to obtain oxygen!

17 The branchial breathing system in teleost fish Gill ventilation Integration of bucal and opercular pumps Countercurrent gas exchange More oxygen demand > Gill ventilation > Lamellar recruitment Ram ventilation

18 The circulatory plan in gill-breathing fish Circulation The closed circulatory plan in gill-breathing fish is in SERIES with the systemic tissues There is not heart between the gills and the systemic circulation Closed circulatory system of an octopus Open circulatory system of a crayfish or lobster

19 Water salt relations in marine organisms Isosmotic Hyposmotic Organic solutes play a major role in osmotic regulation

20 Water salt relations in Water salt marine vertebrates relations in marine vertebrates

21 Excretion in marine teleost Urine isosmotic to plasma concentrated and small amount

22 Senses in the ocean: photoreceptive structures Photoreceptors: contain photopigments (absorb light ---transduce into electrical signal).

23 Senses in the ocean: mechanical senses Nervous system connected to pores on surface, detect changes in water motion or pressure Invertebrates: mechanoreceptors Statocyst: Calcium carbonate body, cilia senses Fish: mechanoreceptors Hair cells: one kinocilium, several stereocilia

24 Living in the ocean: conclusions Most phyla of animals live in the sea At the cellular level, physiological systems have evolved against a marine background, with fairly constant conditions of salinity, temperature and gas availability. The marine environment do not impose a great physiological challenge to most marine organisms. More challenging for animals that have invaded the sea secondarily

25 Terrestrial life The properties of air mean that to succeed on land animals need: 1. More specific adaptation of the skeleton framework and motile system. 2. More physiological control of water and thermal balance. 3. Sensory, neurological and behavioral adaptations to permit a more active mode of life.

26 Terrestrial life life

27 Terrestrial biomes Temperate forests (dense litter layer) Temperate and tropical grasslands and scrublands (grazers) Tropical rainforests (vertical stratification)

28 Terrestrial biomes biomes

29 Primary productivity and distribution of animals Primary productivity Climates and Microclimates: Effects of soil (temperature and water) Effects of vegetation (temperature and water)

30 Terrestrial life life Categories of terrestrial animals Interstitial fauna: small animals, living in soils (similar life freshwater) Cryptozoic fauna: soil dwelling Hygrophilic fauna: high humidity Xerophilic fauna: dry conditions

31 Problems and advantages of life on land Problem: terrestrial habitats are more instable and unpredictable (temperature, gases, etc) More physiological control of water-thermal balance with a need for integration of water balance, temperature balance and respiration. Oxygen supply: is much easier. More Oxygen, easier ventilation. Higher metabolism possible. Problem: respiratory water loss (internal lungs, nasal exchange systems).

32 Problems and and advantages of life on on land land Water-salt equilibrium: Water and salts have a continuous tendency to leak from the body, so must be regulated by careful control of skin, respiratory and excretory surfaces. Adaptations for water balance: Behavioral regulation (first line of defence) Skin and cuticles Regulatory organs: kidneys Salts must be obtained from food. But it stays in the body more easily. Water and ion balance by eating and drinking

33 Problems and and advantages of life on on land land Thermal adaptations Air: lower thermal conductivity and specific heat than water. Easier to maintain a gradient between body temperature and ambient temperature. Ectotherms: thermal avoidance and thermal tolerance, Behavioral regulation of gain heat, Behavioral regulation to conserve heat. Endotherms: thermal avoidance and thermal tolerance, Behavioral regulation to gain heat and conserve heat. Physiological regulation.

34 Thermal adaptations COLD : Temperatures below thermoneutrality Modulation of Insulation: Adjustment of pelage or plumage: Vasomotor response (blood flow to surface areas) Postural responses (change body surface exposed) Metabolism insulation Modulation of Heat production (Thermogenesis). Thermogenesis by shivering. Non- shivering thermogenesis (brown fat)

35 Thermal adaptations HOT: Temperatures above thermoneutrality 1. BEHAVIOUR! Restrict activities 2. Facilitate heat transfer: circulation. 3. Active evaporative cooling (sweating, panting, gular fluttering, saliva spreading)

36 Problems and advantages of life on land Terrestrial life Nutrition: Trophic structures are more complex in land. Great development of primary producers (14000 times greater carbohydrates reserves). Herbivores (symbioses with heterotrophic microbes) No filter feeders and sessile strategies. Food must be actively sought. Metabolism: in general higher.

37 Problems and and advantages of life on on land land More specific adaptation of the skeleton framework and motile system. Problem: Support of the body (water 1000 more dense than air). Support of the body is much harder in terrestrial habitats. Need skeletons. Exoskeleton insects---- molting Motility is an issue. Faster organisms. Flying is adopted as the main form of moving around. Advantage: air less viscous. Movement easier, acceleration.

38 Problems and and advantages of life on on land land Communications: are more complex in air. Better visual communication over long distances More sophisticated sound production. More complex chemical messages (pheromones) (markers in soil) Photoreceptors: contain photopigments (absorb light ---transduce into electrical signal)

39 Fresh water Moving or Lotic water Still or Lentic water 3 % of all water is fresh (2/3 ice) % free fresh water (underground) % is visible Extremely productive areas Great impact on Terrestrial habitat

40 Fresh water Highly variable habitat Osmoregulation: Very dilute habitat --- osmoregulatory problems (no osmocomformers, no avoidance strategies) Thermoregulation: strong thermoclines. (High water conductivity) Mostly ectotherms Oxygen levels: low Reproduction tricky (young stages very vulnerable) (Few taxa) Short life cycle-strategies. Long life-cycle strategies with dormant stages.