Inquiry Based and Science Literacy Project Petrogale assimilis (Allied Rock Wallabi)


Inquiry Based and Science Literacy Project: Petrogale assimilis(Allied Rock Wallabi)

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Inquiry-based and science literacy project: Petrogale assimilis(Allied Rock Wallabi)

Petrogale assimilis live within rocky outcrops. According toFisher &amp Owens (2000), they are only found in Mainland Australiaand some other off show islands. They are however not found inTasmania and New Guinea. A good number of Petrogale assimilis arefound in the arid and tropical parts of Australia. According toFisher &amp Owens (2000), given their agility between the shoulders,these animals look quite awkward in the open country. He also saysthat these animals are rarely spotted in their rocky habitats giventhe speed with which they can escape from boulder to boulder. Anumber of the animal’s behavior and physical features are areflection of their lifestyle in the rocky habitat. Other featuresthat adapt them to their rocky habitat are short claws that help themmove from one rock to another, large hindfeet for tracking their preyin the rocks and a long tail for balance when jumping between therocks.

The animals are herbivorous. Petrogale assimilis mainly feedson grass shoots and seeds. According to Fisher &amp Owens (2000),the animals also feed on fruits and flowers. They also feed onunderground root plants, bulbs and rhizomes. The animals also take alot of water alongside their food. However, according to Fisher &ampOwens (2000), the amount of water that the animals take varies withthe availability, either directly or indirectly. They mainly feed onthe grasses at dawn and at dusk. When other softer foods areunavailable, the animals chew of hard desert barks. According toFisher &amp Owens (2000), Petrogale assimilis also likefeeding on herbaceous flowering plants. They also brush on younggrasses and saltbushes. According to research by Fisher &amp Owens(2000), the animals use darkness as cover when they are foraging.Breeding pairs have been observed to have a tendency of eatingtogether. As for the single animals, they like being near to otherswhen they are eating.

Cardillo et al. (2004) did research to construct a phylogenetic treeof life. In this research, they used an unweight supertreerelationships for the Macropodide and Potoroidae families. In orderto do this, they used the information on phylogenetic relationship,which however, used complete species-level phylogenetic information.According to research conducted by Cardillo et al, the strategy thatis used to characterize Petrogale assimilis is their life inthe rocky habitat and devotion to locomotion rather than rapidgrowth. The animal’s habitat structure is also important whenclassifying and putting them up in the phylogenetic tree of life. Theanimal’s tendency of being a generalist and opportunistic feedersis another distinguishing feature of putting them up in thephylogenetic tree of life.

According to Hazlitt et al. (2006), discontinuous gas exchange (DGE)is the main breathing mode for a resting adult. When they areyounger, they display a pattern of cyclic gas exchange (CGE).Abdominal pumping accompanies the burst of Carbon Dioxide that isreleased from their bodies. This is what Hazlitt et al. (2006) refersto as active ventilation. Additionally, Kivimagi et al describes apattern of continued respiration, which is characterized by regularabdominal pumping. Their resting metabolic rate is also high, andwhen they are treated with sub-lethal doses of alpha-cypermethrin,the discontinuous gas exchange seizes. Hazlitt et al (2006) say thatone of the major components of the specie’s metabolism is proteinsynthesis and degradation. According to him, the energy costs aredirectly related to the whole body protein synthesis. This isinvolved in other processes that aid in protein synthesis. Thespecies’ whole body protein synthesis is significantly lower thanall other animals living in the same habitat. Additionally, thedifference in protein turnover rate between the animal and othermarsupials is manifested in the inevitable loss of nitrogen, mainlythrough their feces.

According to Hazlitt et al. (2006), the Petrogale assimilis uselittle energy to breather when they are jumping than when they arestationary. This is because they use a little muscle to breathe whenthey are moving from rock to rock. As they get the air into theirlungs when moving about, the thoracic cavity opens up, reducing thealveolar pressure below the atmospheric pressure. The oxygen getsabsorbed into the body, where it is transported to all other organsin the body. They have a series of blood vessels all over the body,which supplies the oxygen to these organs. When they breather out,they release carbon dioxide and other gasses, which completes therespiratory system. One of the main gasses that they expel from theirsystem is nitrogen. The animals’ nitrogen intake helps to maintainthe oxygen balance in their bodies. Other ways of nitrogen loss fromthe body, apart from feaces and urine, are hair shedding and sloughedskin, which however, is quite insignificant.

According to Morino (2009), one of the excretion products that isunique to the species is creatinine. Creatinine is a metabolicend-product of creatine. This is a high-energy precursor, which ismainly found in their muscles. It is synthesized in the liver andfrom inter conversion of creatine and phosphocreatine in the muscle.The species excretes urine as a product of the process of bloodpurification in the kidneys. The urine is excreted from the nearbygenitalia. They excrete carbon dioxide through the lungs when theybreathe out. They also have excretory glands, which are common to allmammals.

According to Old &amp Deane (2000), the animal is of unique interestto researchers mainly because of its vigorous immune system. They areable to survive several kinds of parasite infections and viruses.Additionally, their recovery rate from diseases is higher than thatof all other animals living in the same habitat. They have a hightolerance of the fetal tissues, which is used by the maternal immunesystem for higher penetration of maternal tissues and intimatevascular beds. Old &amp Deane (2000) says that the species did notevolve a trophoblast, enabling it to mask histocompatibility antigensin their surface. Apart from the masking the antigens in theirsystem, the trophoblast layer helps them to adapt to gestation, whichis a main dichotomy for marsupials, which enables them a to fight offthe germs they consume or get into contact with while feeding becauseof a strong immune system.

A number of researchers have described the species’ endocrinesystem. According to Old &amp Deane (2000), it has been summarizedas an extension of the secretory phase of the corpus luteum, andhaving the ability to become quiescent, associated with the embryo asit enters the diapause stage of the unilaminar blastocyst. Old &ampDeane (2000) say that the animal’s macropodid hypothalamus hasreceived little attention from biological research, and that most ofthe information regarding its secretory has been obtained indirectly.Despite the fact that there is increasing knowledge about theanimal’s pituitary functioning, its structure has not been welldescribed in the literature. However, a known fact is that there arethree zones in animal’s pars distalis. Their adrenal structure issimilar to that of other micropods. Their unilateral adrenalectomy isbecause of the remaining structure, which is caused by its large zonafasciculatus. Old &amp Deane (2000) say that an adrenal-relatedfunction, which is peculiar to many members of the macropodids, hasan insensitivity to the diabetogenic and nitrogen mobilizing actions.Environmental conditions are the reasons why the species have areduced adrenal structure.

The species are characterized by the development of their offspringin a leathery egg, which is laid into their abdominal pouch. As theygrow, their brain begins to develop, and the nervous system begins todevelop. Just like all other animals, their central nervous system isconnected to the brain through the spine. Old &amp Deane (2000) saythat the ventral root outgrowth at the base of the fore limbs is 6 mmlong. Qualitative and quantitative study that has been piloted abouttheir nervous system reveals that the animals do not have anystructural differences with other marsupials. Additionally, thedifferentiation of the ventral horn occurs during incubation, wherealso separate medial and lateral motor column development takesplace. Another uniqueness of their nervous system is that it isprimitive and underdeveloped, and lacks a corpus callosum. Theanimal’s cerebral circulation is also quite unusual, and it has astrange cortical organization of their sensory motor system. Researchthat has been conducted over the past one and half century revealsthat the animal’s central nervous system has a degree oforganization, which is quite complex and different from otheranimals’.


Cardillo, M., Emonds, O., Boakes, E. &amp Purvis, A. (2004). Aspecies-level phylogenetic supertree of marsupials. The ZoologicalSociety of London. 264, 11-31.

Fisher, D. O., &amp Owens, I. P.(2000). Female home range size and the evolution of socialorganization in macropod marsupials.&nbspJournalof Animal Ecology,&nbsp69(6),1083-1098.

Hazlitt, S. L., Sigg, D. P.,Eldridge, M. D. B., &amp Goldizen, A. W. (2006). Restricted matingdispersal and strong breeding group structure in a mid‐sizedmarsupial mammal (Petrogale penicillata).&nbspMolecularEcology,&nbsp15(10),2997-3007.

Kivimagi, I., Kuusik, A., Ploomi, A., Metspalu, L., Jogar, K.,Williams, I., Sibul, I., Hiiesaar, K., Luik, A. &amp Mand, M.(2013). Gas exchange patterns in Platunus Assimilis: Respiratoryfailure induced by a pyrethroid. Europe Journal of Entomology. 110(1): 47-54.

Morino, L. (2009). Monogamy inmammals: expanding the perspective on hylobatid mating systems.In&nbspTheGibbons&nbsp(pp.279-311). Springer New York.

Old, J. M., &amp Deane, E. M.(2000). Development of the immune system and immunological protectionin marsupial pouch young.&nbspDevelopmental&amp Comparative Immunology,&nbsp24(5),445-454.