What do you think is the largest single cell on earth? Remember there are limits to the size of cells due to absorption of nutrients and oxygen and release of wastes. How does a cell bigger than a cricket ball manage these limits? Where do you think you would find such an organism? These strange forms of life belong to the Kingdom Protista and have been discovered in deep ocean trenches, over ten kilometres beneath the surface. Read more about these fascinating xenophyophores at “Strange Forms of Life Discovered in Ocean’s Blackest Depths“.
Learning Intention: Students will understand the benefits and energy costs of a range of reproductive adaptations. They will compare ‘r’ and ‘K’ strategies and learn how they assist survival of the species.
Success Criteria: Students will be able to describe various reproductive strategies in plants and animals and explain how they assist survival of the species.
Link for our Elluminate session (Friday 22nd July, periods 1 and 2): https://sas.elluminate.com/m.jnlp?sid=2007026&password=M.8E3BE08DC2C05955C950883EC4C9AB
Learning Intention: For students to be able to understand what behavioural adaptations are, how they can assist the survival of different species and to be able to identify different types of behavioural adaptations.
Success Criteria: You will be able to identify several examples of innate and learned animal behaviours and describe how they assist each organism to survive in their environment.
Any actions that an animal takes to assist it’s survival – feeding, mating, hibernating, migrating, nesting, fighting for territory or resting in shade – are behavioral adaptations that have evolved over generations. Some behaviors are ‘innate’ or instinctive and occur in all animals of the same species, even if they are isolated from their parents and siblings. These behaviors are genetically programmed, while others are learned behaviors. Learned behaviors require an organism to observe the behavior.
An example of insect behaviour is the “waggle dance” that directs bees to sources of food – read more about it at NOVA. For more examples of animal and plant adaptations, check out this Scoop.it magazine I created, with some interesting articles. From D’Anne Witkowski’s blog - “Unique among primates, gelada males have a patch of bare skin on their chest that changes in color according to status. Beehner believes that this relationship (between color and status) might be linked by testosterone. As testosterone levels rise, male chests change from pale pink to bright red. Simply put, this chest patch could be a signal to other males, a way for males to decide whether they want to pick a fight with a high-testosterone rival or not.”
This Creative Commons Image from Wikimedia
Learning Intention: Students will develop an understanding of the terms and definitions used and how physiological adaptations allow organisms to survive in their environment.
Success Criteria: Students will be able to describe a range of physiological adaptations and how those adaptations allow organsims to survive in their environment.
Adaptations to an organism’s environment can usually be identified as structual (physical – how an organism is built), functional (physiological – how an organism works inside) or behavioural (what an organism does). Chapter 10 deals with physiological adaptations. The following is an interesting article created by a student at Davidson College for an Animal Physiology course.
The Australian koala (Phascolarctos cinereus) is a remarkable animal, and is one of only a few animals, that is capable of surviving on a naturally foliar diet of eucalyptus leaves. Over time, the Koala has evolved several physiological adaptations that allow it to cope with this high fibre, low protein diet. Low metabolic rates allow koalas to retain food within their digestive system for a long period of time, maximizing the amount of energy able to be extracted. Cork and Warner conducted interesting studies on the digestion and metabolism of Eucalyptus foliage in koalas. Using radioisotopic markers, they examined the passage of particulate and solute digesta through the alimentary tract of the koala. They found that the solute marker was retained for longer periods of time than the particulate marker. The mean retention times for the solute and particulate markers were 213 hours and 99 hours respectively. These times are longer than those reported in most other mammals (1983). The selective retention of solutes and fine particles maximizes the energy withdrawn, particularly from non cell-wall constituents. More importantly however, the relatively quick passage of larger fibrous particles, or plant cell-wall constituents, is thought to reduce the “gut-filling” effect of the foliar diet. This extends the upper limits of food intake and ultimately increases the availability of nutrients, partially compensating for the constraints of small body size (1983). Passage of the larger fibrous particles is also beneficial because other researchers found that only 25% of the the cell-wall constituents that enter the alimentary tract are able to be digested (Cork et al., 1983). Breakdown of the cell contents is most important in the digestive process.”
Check out the Hawkesdale Biology wiki page for more links and information about the physiological adaptations of organisms that enable them to extend their tolerance limits and therefor their distribution and abundance. One of last year’s students created this set of Chapter 10 Flashcards to assist her to remember the terms and definitions from this chapter of work.
Author’s photo taken at the Leaning Trees of Greenough, Western Australia
Learning Intention: Students will understand the biotic and abiotic factors that affect the distribution and abundance of organisms on earth.
Success Criteria: Students will successfully complete the Chapter 9 review questions and be able to list biotic and abiotic factors that affect the survival of organisms on earth.
Buffeted by the prevailing southerly winds, these eucalypts have survived despite challenging conditions. The survival of organisms, and therefore their distribuition and abundance, depends on both biotic (living – predators, competitors, pathogens, parasites) and abiotic (physical – temperature, wind speed, pH, atmospheric gases, turbidity, salinity, solar radiation) factors. This chapter of work is about habitats and the factors that affect the survival of organisms in their environments. Learn some definitions for this chapter at Chapter 9: Habitat and Survival Flashcards. You will also learn about niches and resource use graphs. Match some Australian species to their habitats at DECC.
Living organisms survive in their environments due to structual, functional and behavioural adaptations. Evolution is the process by which living organisms have changed over thousands of years to become more suited to their environments. Google ‘evolution’ and you will find an enormous selection of contradictory articles confirming or condemning “The Theory of Evolution”, first proposed by Charles Darwin in 1859.
To summarise Darwin’s Theory of Evolution;
1. Variation: There is variation in every population.
2. Competition: Organisms compete for limited resources.
3. Offspring: Organisms produce more offspring than can survive.
4. Genetics: Organisms pass genetic traits on to their offspring.
5. Natural Selection: Those organisms with the most beneficial traits are more likely to survive and reproduce.
Tonight on ABC1 you may have been lucky enough to watch “Life” narrated by David Attenborough. This, the first of three episodes, was about fish – their variety, feeding and reproductive behaviours, habitats and predators. It began with footage taken in southern Australian waters, of the weedy sea dragon, showing how the male and female court by ‘dancing’ then the female transfers the fertilized eggs to the male, who looks after them until they hatch. The tiny hatchlings wriggle free from the father’s belly-fold and begin to feed, with their yolk sac still attached. The anglerfish has another unusual method of reproduction, in which the male is ‘parasitic’ on the female. The tiny male embeds itself in the female and disintegrates into the female’s flesh, until all that is left is the testes.
Praying mantids exhibit another unusual method of reproduction, in which the male has a good chance of his head being bitten off during mating. If the male happens to lose his rigid grip from atop the female, he is at risk of sexual cannibalism – the female gets a nutritous meal as well as continued copulation, as the nerves that stop copulation are in the head, and the nerves that continue copulation are in the abdomen. Dragonflies and damselflies also display unusual courtship. Eggs may be deposited underwater, drilled into mud, carved into stems, or dropped while in flight.
The green spoonworm (Bonellia viridis) is another species in which the female dominates – in fact you are unlikely to find a male spoonworm at all. The spoonworms begin life as free-swimming larvae, which settle to the bottom of the Mediterranean Sea and slowly develop. If the larvae happen to settle on another female, the female releases a chemical that turns the larvae into a tiny male, which migrates through her mouth into the uterus and assumes a parasitic existence. The female can have up to twenty tiny males inside her genital sac, so she expends no energy looking for a mate, while the male benefits by having a safe and secure space, relying on the female for nutrition.
In a recent article in The Age, “Cheating is risky, but worth it, for female finches”, Adam Carey writes about the reproductive strategies of the beautiful Gouldian Finches, which have an unusually high rate of intra-species incompatability. “Gouldian finches mate two to four times a day during breeding season, but given the opportunity, the female will covertly cuckold her mate, also going to great lengths to keep it a secret. Males will help to incubate eggs and feed chicks, unless the female’s infidelity becomes known, in which case he might abandon the brood.” So what motivates the female to take such a risk? Scientists believe that the female can choose genetically superior mates and maximizes her chance of conceiving healthy offspring by ‘cheating’ on her mate. A superior male can fertilize up to 75% of a female’s eggs, making even one copulation worthwhile.
Mating behaviour in animals - monogamy, polygamy, polygyny and polyandry.
Image Source – Cold-tolerant Wood Frog
Wood frogs (Rana sylvatica) are found in the northern parts of North America where the temperature can get very cold. When the wood frog experiences chilly conditions, a chemical signal is sent through it’s boy which prepares the frog to be frozen. The frog can remain frozen solid for the whole winter. The frog’s heart stops beating during this time also. It feels rock hard and looks dead but is not. When the weather starts to get warmer in the spring, the frog thaws out just in time for mating season. The frog can stay frozen without dying because of the way it stores glucose, which lowers the freezing point of water. The frog is able to build up the concentration of glucose in it’s cells, so that the cytoplasm doesn’t freeze, even when the interstitial water freezes. Two-thirds of the water in the frog’s body can freeze into ice crystals.
(Student post from an article in “Scientriffic” by Priyanka Shewpersad)
Image Source – Winter vegetable garden
Winter vegetables, such as broccoli, cabbage, cauliflower and brussel sprouts, are also frost-tolerant. These plants have genes that allow “antifreeze proteins” to be produced, which prevent the plant cells from being damaged by frost.
Budgerigars – Melopsittacus undulatus
The following posts are by students, about the structual, functional and behavioural features of vertebrates that live in arid environments, that enable them to balance their water requirements.
-Small size of the budgie means that the water requirements are minimal.
-Budgerigars save water by excreting thier waste as nitrogenous waste.
– the budgies will huddle together in dry weather to reduce water loss by reducing thier movement and loss of water through sweat glands.
-they eats seeds with a high water content
– the budgies excrete most of their nitrogenous waste as uric acid which can be contolled as to how dry or wet it is depending on water availability
Euro or wallaroo – Macropus robustus
- have bare muzzles
- have large ears
- can obtain all necessary water from food during dry spells
Flounder – Platichthys flesus
Structural features of the flounder
- The flouder has a a minute body cavity that helps the flouder stay on the bottom of the ocean.
- Lack of air bladder helps the flouder to stay on the bottom of the ocean.
- Eyes on the up side of their body helps to spot pray and predators.
- The top side of the flouders is dark and the bottom side is light.
- They have strong teeth and jaw.
- They have a large mouth.
- Pusterior fin flatter and broader to swim faster and helps to swim on side
Functional features of the flounder
- tolerance for low salinity
- has diluted urine in fresh water
- concntrated urine in salt water
behavioural features of flounder
- Change color of skin to match surroundings to hide from predators
- bury themselves in the sand to hide from predators or to catch pray
- change shape to help find food
- go from river to sea
Over the semester break, please read through Chapter 10 carefully and start to answer the Chapter review questions. Leave a comment below or email me if you have any trouble with those questions. Physiological adaptations are ways that organisms are able to survive due to the way that they function. So succulent plants, such as those pictured above in Port Fairy, and mangroves are able to tolerate salty environments due to physiological features such as a thick cuticle that reduces water loss and salt glands that excrete excess salt.
Koalas have physiological adaptations that enable them to survive on a high fibre, low protein diet. As well as the obvious behavioural adaptations (usually slow moving and sleepy), koalas have reduced metabolic requirements and a slow metabolism, that enables them to survive on a diet of Eucalyptus leaves. Living organisms have evolved a great variety of strategies that enable them to survive extreme conditions in almost every place on the planet – temperature (hot and cold); moisture (wet and dry); chemical (high salinity for example); oxygen availability and fire tolerance. Some great examples at BBC Wildlife Finder – Adaptations.
You might think that providing water in arid areas would allow native species to flourish, as well as the stock it is intended to supply. However, sinking bores and providing tanks or troughs allows larger predators of native species access to areas that previously they found too dry to survive in. Small, native marsupials have become increasingly rare in the arid zones of Australia due to increased predation from both indigenous predators (wedge-tailed eagles, dingoes, dasyrids) and feral pests (foxes, feral cats, wild dogs). These predators have wide home ranges in desert areas and need to have access to water to survive. Smaller marsupials manage to survive in very dry areas due to a number of structural, functional and behavioural adaptations. These may include low SA:V ratio that reduces evaporation, nocturnal or crepuscular feeding habits, concentrated urine and dry faeces and the ability to obtain their water needs from the food they eat, without drinking.
Martin Westbrook is an environmental scientist working with the University of Ballarat at Nanya station, 140 km north of Mildura. He has been able to perform experiments at the 40,000 hectare former pastoral property, to determine the impact on biodiversity when removing water points. The Age has produced an article about his research here.