Biology Classification Zebras have a distinctive striped pattern that makes them easily recognizable to most people, but they also display features common to many other animals. So how can we easily compare animals? This is a print version of an interactive online lesson. To sign up for the real thing or for curriculum details about the lesson go to www.cosmoslessons.com Introduction: Classication Why do zebras have stripes? It’s a question that scientists have been asking for more than 100 years but now new research may nally have an answer. Most animal species have developed distinctive colours and patterns to help disguise them in their natural environment. Like a soldier’s camouage, the colouring and patterns look like the background, so it's hard to tell the dierence between the animal and its surroundings. But zebras live on brown grassy plains and their stripes make them stand out, not disappear. They may as well be holding signs for the lions saying, “come and eat me”. Now we may have the answer. By studying where most zebras live, scientists have found that the animals share their home with lots of nasty biting tsetse ies and horse ies. They also discovered that these ies don’t like striped patterns and will stay away from them. So, it’s likely that the zebras developed stripes to act as an insect repellent. That may sound crazy – to make yourself a target for lions just to keep away the ies. But these aren’t ordinary irritating ies. Tsetse ies carry diseases that can kill, while horse ies tear the animals’ skins leaving them at risk of infections. Believe it or not, to a zebra infectious diseases are actually more dangerous than lions! Read the full Cosmos Magazine article here. A plains (or Burchell's) zebra (left) and a donkey, approximately to scale. Question 1 Observe: A lot of science is about good observation. Look closely at the pictures of the zebra and donkey above and list four similarities and four dierences. Note: If there's time and the teacher doesn't mind, don't stop at four – see how many similarities and dierences you can get. 1 Gather: Classication You may already know that we can divide the things around us into two groups: living and non-living. Living things can move, respire, grow, reproduce, eat, excrete and respond to the environment around them. But how can we distinguish one living thing from another and why is this important? 0:00 / 3:59 Credit: Classication of Living Things by Mark Drollinger (YouTube). 2 Question 1 Notes: Use this space to take notes for the video. Note: This is not a question and is optional, but we recommend taking notes – they will help you remember the main points of the video and also help if you need to come back to answer a question or review the lesson. Question 2 Question 3 Recall: Greek or Latin words are used to classify living Recall: The bear was eliminated from the group of animals things because they are known all around the world. at the level: True Animalia False Chordata I'm not sure Mammalia Carnivora Felidae I'm not sure Living things are divided into kingdoms. There are six in all: animals, plants, bacteria, archaea, fungi and protists. This lesson will focus on the animal kingdom, or Animalia. The animal kingdom is divided into many dierent phyla but a simple division is between vertebrates (Chordata) and invertebrates. Vertebrates are animals that have a backbone, while invertebrates are animals without a backbone. Vertebrates are divided into ve classes – mammals, sh, birds, reptiles and amphibians. Question 4 Think: Why do we classify organisms? 3 Question 5 Describe: Complete the diagram below by adding the following for each class of vertebrates: their typical surface covering, how they give birth, whether they are warm- or cold-blooded, and an example. The rst class has been completed for you. Hint: You may need to perform an internet search to help with some of the features. Question 6 Select: Which class do you think zebras and white tigers best t into? Justify your choice. 4 Process: Classication 0:00 / 2:38 Credit: Dichotomous Key by Mark Drollinger (YouTube). Question 1 Notes: Use this space to take notes for the video. Note: This is not a question and is optional. 5 Question 2 Classify: From the images above, select the animal that best suits each blank space to complete the dichotomous key. Behavioural or physical feature Action or species 1 ying go to 2 not ying go to 6 2 feathered go to 3 not feathered Little brown bat 3 web-footed, water dwelling Mallard duck not web-footed, not water dwelling go to 4 4 hovering ight, very small Ruby-throated hummingbird not hovering ight go to 5 5 mouse eater, nocturnal Great horned owl insect eater, diurnal American robin 6 hairy or furred, mammalian go to 8 not hairy, not furred, not mammalian go to 7 7 legs present legs absent 8 aquatic animal Harbour seal land animal go to 9 9 hopping or jumping locomotion go to 10 not hopping or jumping locomotion go to 11 10 large with tail used for balance small with small bobbed tail 11 large at leathery tail Beaver tail neither at nor leathery go to 12 12 hoofed, herbivorous go to 13 not hoofed, omnivorous or carnivorous 13 spotted or striped coat go to 14 no spots or stripes on coat 14 spots on coat stripes on coat 6 Question 3 Determine: Do you think that two animals' coat colour and pattern is sucient to determine whether or not they belong to the same species? Support your answer with an example. Question 4 Think: New species are discovered every year. What diculties do you think researchers might have in determining whether or not an organism belongs to a new or existing species? Question 5 Research: The classication of the plains zebra is: Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Perissodactyla Family: Equidae Genus: Equus Species: quagga Use the internet to nd out the genus and species of the three other animals shown below. Note: The genus always begins with a capital letter and the species is always written in lower case. 7 Question 6 Recall: The Cosmos Magazine article stated four theories for why zebras have stripes. What were they? Question 7 Calculate: The approximate distribution of the three species of zebra can be seen on the map above. If the continent of Africa is approximately 30,244,049 km2, calculate the approximate area (in square kilometres) that each species occupies. Approximate fraction of Africa Species Area (square kilometres) occupied 1 Grevy's zebra /100 1 Plains zebra /5 1 Mountain zebra /80 8 Project: Classication Classifying striped animals Background This task will test your understanding of classication and of how dichotomous keys can be used to identify species based on their distinguishing features. You will need to carefully study the eight striped animals shown above and see if you can zero in on their key similarities and dierences. Are you ready for this stripy challenge? 9 Question 1 Complete: Complete the following table to identify the eight species by their common names and summarize their distinguishing features. The features you will need to consider are whether or not they: have a backbone, live in the sea, have legs, have hooves, have horns and have a regular striped pattern. In the next question you will use this information to construct a dichotomous key for these species. Hint: An internet search of the genus and species will help you nd the common names and any extra information you might need. Common name of Lives in Regular Image Genus and species Backbone Legs Hooves Horns species the sea stripes Equus quagga yes no Red lionsh Pterois volitans no no no Purple-striped Chrysaora colorata no no jellysh Panthera tigris no no Monarch caterpillar Danaus plexippus no yes Lampropeltis getula no no yes californiae Equus ferus yes yes no Tragelaphus eurycerus no yes Recall that a dichotomous key uses specic features to characterize and distinguish species. In this lesson we have seen an example of a step by step tabular dichotomous key, but you can also construct a dichotomous key in graphical form, as shown below. 10 Question 2 Design: Construct a dichotomous key that can be used to distinguish between each of the eight animals pictured at the top of this page. Use the project space provided to create your key in either tabular or graphical form. Illustrate your dichotomous key with an image of each animal sourced from the internet, and remember to include their scientic names (genus and species). You may wish to add additional animals to your key, however you must include all of the animals pictured above. Good luck! 11 Career: Classication Tim Caro was only three years old when his mother gave him a book about birds. Captivated by the beautiful and colourful birds he saw within its pages, young Tim knew then that he wanted to become a zoologist. Tim isn’t satised with just admiring beautiful animals. He wants to know exactly why animals look the way they do. Although we learn about what animals look like as children, he says that few people really understand the reasons behind the striking geometrical patterns of a girae’s coat, or why a panda is black and white. At home in sunny California, Tim divides his time between teaching biology at the University of California and writing books and papers about his research.