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Name: Date: Mammals Characteristics: Are mammals ectotherms or endotherms? How do mammals stay warm? Hair insulates most mammals Some marine mammals have a layer of subcutaneous fat (blubber) Nutrient intake: Specialized teeth Incisors – biting Canines - stabbing, holding molars - crushing, grinding Different types of mammals have different types of teeth depending on their diet Predators have large canines - The canines of predators are very large and sharp, used for tearing flesh Herbivores have large flat molars Mammals have diverse diets. Herbivores often have an extra stomach chamber called a RUMEN to help them digest plants The rumen holds bacteria that can digest plant material Circulation Mammals have a 4 – chambered heart and double loop circulation. What other animals have a double loop? Movement: Block: Mammals are TETRAPODS, meaning they have four limbs. These limbs can be adapted to different functions, such as the wings of bats or the flippers of whales. An animal that is BIPEDAL walks on two legs. Whales do not have hind limbs, but they do have VESTIGIAL pelvic bones. Reproduction Most mammals give birth to live young. Placental mammals: A placenta is attached to the wall of the uterus , it provides the fetus with nourishment. Mammary glands are only found in mammals. They produce milk to feed young. Placental Mammals have a gestation period The exceptions to placental mammals are: Order Monotremata: o Egg laying mammals found only in Australia o Have reptilian characteristics (cloaca & egg laying) o Have mammalian features (hair, mammary gland) o Examples: Order Marsupiala o Mammals bear their young in an immature state, babies develop in a pouch o Majority are found on Australia, opossums are found on other continents o Examples: Biogeography of Mammals Why do animals on different continents look alike? Example: Convergent Evolution: Unrelated species are adapted to similar environments and similar NICHES Birds Mammals Birds reproduction: Egg: • • • Amnion: surrounds only the embryo, inner layer of cells secretes amniotic fluid in which the embryo floats Chorion: surrounds all embryonic structures & serves as a protective membrane Allantois (or allantoic sac): works together with chorion to in respiration and excretion; important in storage of nitrogenous wastes (uric acid) General: • • • • Amniotic egg but has to incubate it (embryo is also an endotherm) This requires pre-natal nesting behavior Egg has calcified shell (for sitting on!) Young born immature: need for post-natal behavior and learning – bigger cerebrum