Image Source – 20 Amazing Animal Adaptations for Living in the Desert
Living organisms are spread across the planet in a wide variety of different habitats and environments. Various adaptations assist organisms to survive in the hottest and driest deserts, coldest arctic tundra and wettest rainforests. Structural adaptations are how an organism is built, such as the wings, feathers and hollow bones of birds that assist them to escape from predators and find their food. Functional or physiological adaptations are how an organism works, which you may not necessarily be able to see from the outside, such as the ability of desert dwellers to survive without drinking water by re-absorbing much of the water from their faeces and producing small amounts of very concentrated urine. Behavioural adaptations are the actions that an animal takes – what it does – to survive, such as migration, resting in the heat of the day or huddling with other individuals to conserve body heat and moisture.
This semester we will be starting Unit 2 (Organisms in their Environment) Area of Study 1: Adaptations of Organisms and Unit 4 (Continuity and Change) Area of Study 1: Heredity. We have created Quizlet Sets for each of these topics:
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.
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.”
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.
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)
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.
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.
The yabbies in our school aquarium make suitable subjects for a study of animal behaviour. Can you classify yabby behaviour according the following:
Which are learned behaviours and which are innate? How are each of these behaviours important to the survival of the yabby as a species? How do you think the behaviour of the yabby is modified by being confined to an aquarium? Can you observe yabbies communicating with each other?