What Can I Learn From a Skull?

What Can I Learn From a Skull? Pennsylvania Envirothon 2018

Skulls- Herbivores, Omnivores, and Carnivores Lesson Overview Grade level(s): Elementary School (K-5), Middle School Subjects(s): Biology/Life Science Topic: Ecology Big ideas(s): The skull is designed to protect the brain and sensory organs. Based on the architecture of an animal's skull and teeth, students can deduce many of its dietary and social patterns. Vocabulary words: Herbivore, omnivore, carnivore, canines, molars, incisors, peripheral vision, binocular vision, monocular vision, predator, prey What you need: A variety of skulls. Be sure to get skulls of different types of diets (omnivore, herbivore, carnivore), and different sizes can be fun too. Grouping: Begin as whole class. Then move to small groups/ stations. Setting: Classroom Time needed: 50-60minutes Summary: Students familiarize themselves with different types of animal skulls, eyes, and teeth (Parts of a skull and their function sheet.) From observation they learn to tell which skulls are those of herbivores, omnivores and carnivores. Prerequisites for students: Some animals are herbivores, which means that they eat only plants Some animals are carnivores, which means that they eat only meat Some animals, called omnivores, eat both plants and animals. ("omni" means "all") Learning goals/objectives for students: Students will know that animals have structures that function in growth, survival and reproduction. Students will know that producers and consumers (herbivores, carnivores, omnivores and decomposers) are related in food chains and food webs. Students will use their observational skills to compare and analyze a number of skulls. Content background for instructor: Animal skulls have evolved for nearly 500 million years to protect the brain and sensory organs in vertebrate animals. Each of the skulls feature mechanisms built to support specific functions, including the obtainment of food and processing, optimal sensory information gathering, and the protection of the brain from trauma. Based on the design of an animal s skull, many of its dietary and social patterns can be discerned. There are four main kinds of teeth in mammals (incisors, canines, premolars and molars). Carnivores tend to have long canines which are used to rip and tear meat, sometimes in a scissors like action. In addition, carnivores have sharp molars toward the back of the mouth, used to further rip and shred meat. Carnivores tend to have binocular vision, where their eyes are at the front of the head, which results in a smaller field of view, but allows for depth perception, needed to catch prey. Herbivores tend to have well-developed flat premolars and molars, often with sharp ridges on the tops. Generally herbivores do not have canine teeth, and their incisors are usually large and used to snip off foliage from branches. Because herbivores are often prey for other animals, they generally have their

eyes on the side of their head, which functions to give them a wider field of view, so that they can detect their prey earlier, and have a chance to flee. Omnivores usually have a variety of all kinds of teeth. Humans, bears and raccoons are omnivores, since they eat all kinds of food (both meat and plant material) they need all kinds of teeth. Generally omnivores have eyes on the front of their heads like carnivores, in order to best catch their prey. SKULL FACT Q: Why do some animals have a large sagittal crest? A: Predators that tackle large prey often develop a sagittal crest, since it provides attachment space for the temporalis muscle, which is used to snap the jaws shut. Sagittal crests are often larger in males than in females, because they are associated with larger body size. Q: Why is there a large hole at the base of each skull? A: This hole, called the foramen magnum, allows the spinal cord and nerves to pass from the base of the brain through to the rest of the body. Because it connects the skull to the spine, its placement can be used to determine an animal s typical posture. Q: How do skulls protect horned animals during head butting matches? A: A special honeycombed bone structure around the base of the horns absorbs the shock of impact during repeated head-on collisions, allowing the muskox and many other horned animals to survive dominance competitions without damaging the skull or brain. Q: Are skulls specialized to help an animal chew? A: The skull provides a framework for the face and neck muscles animals that need stronger chewing muscles will develop larger bony attachment ridges for these muscles, such as the sagittal crest along the top of the skull and the zygomatic arches on the sides. Q: Why do humans have such large brains? A: A large brain gives humans the ability to process, integrate and compare a tremendous amount of sensory stimuli. It also allows a great degree of behavioral flexibility and provides an immensely increased capacity for memory. SKULL FACT Due to their environments and lifestyles, many animals require particularly acute senses. These adaptations are sometimes recorded in an animal s skull, where bone has grown to accommodate larger sense organs or a larger brain the center where all sensory intake is processed. All bears are omnivores, but each species has a unique diet their teeth tell the story. Polar bears use sharp canines to rip out chunks of meat. They tend to swallow these chunks without much chewing, so their molars are reduced in size. Black bears eat much more vegetation, so their molars have larger, flatter grinding surfaces. Skulls are often associated with death, but like all bones, they are composed of living tissue. Constantly changing, they grow larger, stronger or weaker depending on age, diet and exercise. They can also heal themselves when broken. Because of this, a skull is like a good book - it can record the major events and traumas in an animal s life. Scientists read skulls to determine how long individuals lived, how healthy they were, and how they died.

Lesson Implementation / Outline Introduction: Begin by asking students, what do teeth do for you and for other animals? Have students list all the verbs they can think of that describe what teeth are used for: For example: to bite and chew... Tell students that they will be observing and identifying different animal skulls today. Remind students that some of the skulls are real (from animals that were once alive) and some of the skulls are models (but that they are very expensive). But remind students that all of the skulls are fragile and need to be treated very gently, otherwise they will break. Activity: Display pictures of a number of different animals with different diets (e.g. bobcat, rabbit, shark, bird, deer, bear). Ask children if all these animals eat the same food. Display pictures of the food these animals eat (mice/small birds, lettuce/seeds, seals/fish, worms/grubs and grass/leaves) and ask children to link the animals to their diet. Which animals only eat plants? Which only eat meat? Review the scientific names for animals that only eat plants, only eat meat or eat both (herbivore, carnivore, omnivore). Teaching activities Show the children skulls (preferably different skulls than they will be using later to identify) pairs of upper and lower incisor teeth (thin edges joined together for cutting), canine teeth (pointy edges for tearing) and molar teeth (two flat edges for chewing and grinding). Write the terms incisor, canine, premolar, and molar on the board.. Demonstrate action of model teeth working and ask children which teeth would be most useful for cutting grass (incisors), chewing grass (molars), tearing meat (canines), and chewing meat (molars). Give children time to respond to partners which kinds of teeth do plant-eaters (herbivores) need and which do meat-eaters (carnivores) need? Tell the students that you are going to look at the skulls of different animals and try to work out which is which just by looking at them. Ask partners to think about: What kind of teeth can they see in each jaw? What would these teeth be useful for? Which do they think is a carnivore skull and which is the herbivore and why? Ask students what other things do they notice about the skulls? How are they different? Where are the eyes located on the skulls? Are the eyes located on the same place for herbivore and carnivore skulls? Why do you think they are in different places? Hand out the accompanying worksheet for students to write down their observations and ideas about each skull. If you'd like you can put names of the animals on the board along with a definition of what they eat, but do not tell the students which skull is which (if there are labels, cover them): For example: - Sea Lion: fish, octopus, squid - Bear: deer, rabbits, fish, berries, insects - Raccoon: fruits, nuts, crayfish, frogs, mice, small birds - Coyote: rabbits, insects, lizards, carrion, berries - Rabbit: grasses, leaves, roots - Deer: grass, leaves, mushrooms, berries, tender buds and twigs

- Sheep: grass, clover, weeds - Bobcat: rabbit, gopher, lizards, birds - Badger: squirrels, rats, gophers, snakes - Human: fish, cow, pig, milk, fruit, leaves, berries, roots, stems Give each group a skull. Tell the students to observe the skull, sketch it and make notes on the sheet provided (or in their lab notebook). Students begin by making observations about the size of the skull and sketching. Then they indicate if they think the animal is a predator or prey and why. They then fill out a chart answering, "Which type of teeth do they have?" and what is their function. Where are their eyes located? Based on this information, which type of animal do you think it is? Is it an Herbivore, Omnivore, or Carnivore? What do you think this animal eats? What is your evidence? What do you think might eat this animal? What is your guess of which animal this might be? If there is time, have students look at another skull and make similar observations and notes. Checking for student understanding: Check students understanding by asking questions: 1. As you look at the skulls, what different types of teeth do you see? 2. Do you think these different teeth have different functions? If so, what do you think they are? 3. Which mammals would you group together based on their teeth? Why? 4. Which mammals seem to have almost no teeth? 5. Which skulls have the sharpest and/or largest teeth? 6. What might you conclude about the diet of these mammals? 7. Which animals are herbivores? 8. Based on their teeth, which animals are carnivores? 9. What other adaptations do carnivores have to help them get food? 10. Look at the skull. What kind of teeth does it have? What kind of diet does it have? Wrap-up / Closure: When students are finished, discuss the results having students report out on each skull, telling what their group decided it was. Ask others who examined the same skulls to also give their guesses. Keep score of the guesses. At the end reveal the answers. Students can see which ones they got correct. Extensions and Reflections Extensions and connections: Have students examine their own teeth using a mirror. What types of teeth do you see? Are they similar or different from other types of mammal s teeth? How do your teeth relate to your diet?

Parts of a Skull and Their Function The teeth: Maybe the first thing you notice will be the TEETH! The teeth will tell you a lot about the animal you re looking at. Look at the bottom picture of human teeth, so you ll know the different type of teeth. Pick up the skulls and look at them! There are four different types of teeth: Incisors are the front teeth, used for cutting and grasping. Canines are next to incisors and are used for tearing. Premolars, located behind the canines, have sharp edges for crushing food. Molars, the very back teeth, are broad, flat grinders. Mammals that eat only meat carnivores: BITE-RIP-TEAR Sharp large canines (fangs) the animal is probably a hunter (predators) carnivore using the sharp canine (fang) teeth to grab, hold, and kill its prey. Sharp molars the animal uses the sharp back teeth to rip and tear the meat. Most predators don t chew their meat they swallow it in chunks or even whole, and digest it later when it s safe from other predators. Sharp incisors the animal uses the sharp front teeth to first grab and kill its prey. Mammals that eat only plants herbivores: BITE-CHOMP Long incisors the animal is probably an herbivore and uses its long flattened incisors to cut vegetation. Diastema the animal lacks canines, and instead has an empty space (called a diastema). Flat molars the animal uses the flat surface to grind down the plants that they have eaten. Mammals that eat both meat and plants omnivores: BITE-CHEW-CHOMP Flat incisors the animal is probably an omnivore and uses its teeth to rip and tear plants. Sharp canines the animal uses the canines (fangs) to rip and tear meat. Pre-molars - the animal uses pre-molars crush meat Flat molars the animal uses the flat surface to grind down plants. The eyes: Usually you ll find the eye sockets. The eye sockets will tell you a lot about the animal you re looking at. Pick up the skulls and look at them! Big eyes Carnivores generally have large eyes placed so that the eyes look forward and the areas of vision of the two eyes overlap. This means that they have binocular vision and they see objects with both eyes at the same time. The animal may be active at night (nocturnal). Eyes in front Omnivores generally have eyes facing mainly to the front. This gives them partly binocular vision and helps them in their search for a wide variety of food. The animal may be a hunter (predator) or live in trees and need to see the next branch to jump to.

Eyes on side Herbivores have eyes that face to the side, giving them monocular vision; an object is seen with only one eye at a time. While herbivores lack depth perception, they can watch for approaching predators in all directions. Some speedy herbivores, like deer, have eyes that overlap slightly. This provides depth perception so they don t run into trees as they flee from danger. The animal may be hunted, a prey animal. Eyes on top the animal may be an animal that lives in water. Eyes on top will help it see anyone trying to hunt it (predators) while it is swimming. Eyes in the front, the animal hunts. Eyes on the side, the animal hides. The noses: The area in front of the eye orbits, called the rostrum, houses the sense of smell. A large rostrum suggests that the animal hunts through scents or uses its nose to probe the ground or flowers. A deer s long nose allows him to scan for predators while grazing. Coyotes hunt by scent and their long noses contain millions of scent receptors. Cats (like the bobcat) hunt by sight and have short noses. The ears: Two pea-shaped structures, called the auditory bulba, house the mammal s inner ear. The larger these nodes are the better the animal s sense of hearing. The jawbones: Like teeth, jawbones help identify a mammal as carnivore, herbivore or omnivore. Carnivore jaws are attached so that they only open and close; the teeth cannot move from side to side. In contrast, herbivore jaws are fastened loosely; this side-to-side motion allows the animal to grind plant material with his molars. Omnivore jaws are more like carnivore jaws because, in general, omnivores eat fruit and seeds not grass and branches.

Skull Observation Recording Sheet Your name: 1. Which # skull do you have? 2. Carefully measure the skull (length and width), How big is it? (Please indicate units): 3. Sketch the skull: 4. Do you think this animal predator or prey? Why? 5. Which type of teeth do they have? Fill out the chart below: Type of tooth Yes or No How many? What do these teeth do? Canine Incisor Molar & Pre-molar

6. Where are the eyes located on the skull? (please circle one) In front On the side On the top 7. Based on the information you have observed, which type of animal do you think it is? (Herbivore, Omnivore, or Carnivore?) 8. What do you think this animal eats? What evidence do you have for this? 9. What do you think might eat this animal? 10. What is your guess of which animal this might be?

6 The University of Arizona Cooperative Extension COYOTE

DEER Wildlife Skull Activities 7

Opossum Dental formula: 5/4, 1/1, 3/3, 4/4