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CLASS MAMMALIA

CLASS MAMMALIA . Domain: Eukarya Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata . MAJOR CHARACTERISTICS . All mammals share 6 major characteristics : Endothermy Hair Completely divided heart Milk Single jawbone Specialized teeth. Endothermy.

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CLASS MAMMALIA

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  1. CLASS MAMMALIA Domain: Eukarya Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata

  2. MAJOR CHARACTERISTICS • All mammals share 6 major characteristics : • Endothermy • Hair • Completely divided heart • Milk • Single jawbone • Specialized teeth

  3. Endothermy • Regulate body heat internally through metabolism and externally through insulation Hair • all have some hair • Most are covered with a thick coat of hair, which insulates the body against heat loss • Hair is made of filaments of keratin

  4. Completely Divided Heart • Have 4 chambered heart whose 2 ventricles are completely separated by a muscular wall • Division keeps deoxygenated blood from mixing with oxygenated blood • Allows efficient pumping of blood through the circulatory system

  5. GOT M I L K? • Females produce milk to feed offspring • Milk=nutritious fluid that contains fats, protein & sugars • Produced in mammary glands • Modified sweat glands located on the thorax or abdomen

  6. SINGLE jawbone • Lower jaw is made up of a single bone • By comparison, a reptile’s is made up of several bones • Mammalian fossils are often identified by the jawbone

  7. Specialized Teeth • Various types of teeth modified for different fx • Teeth at the front of the jaw bite, cut, or hold prey • Teeth along the sides of the jaw crush, grind, or slice • By comparison, most reptiles’ teeth are uniformly sharp and conelike throughout the mouth

  8. Ancestors of mammals • Appeared more than 300 million years ago • Amniotes (group of tetrapods that have a terrestrial adapted egg) split in 2 groups • One group gave rise to dinosaurs, birds, and modern reptiles • Other group –SYNAPSIDS-gave rise to mammals & their extinct relatives (small structure) • THERAPSIDS appeared from SYNAPSIDS and gave rise to mammals

  9. Early Mammals • 1st dinosaurs and 1st mammals appeared during the Triassic period • Early mammals were about the size of mice • Fossil skulls with large eye socket suggest that they were nocturnal • Teeth were adapted for feeding on insects • Hiding by day & specializing on insects allowed mammals to avoid threats from dinosaurs or competition w/ them • Similarities in mammary tissues of several kinds of mammals suggest that milk production had evolved by the end of the Triassic period

  10. Diversification of Mammals • Dinosaurs dominated most terrestrial habitats while populations of small mammals continued to evolve • By end of Cretaceous period (100 million years ago) 3 different types of kinds of mammals existed • MODERN MAMMALS BELONG TO ONE OF THESE 3 GROUPS • 1.) MONOTREMES • 2.) MARSUPIALS • 3.) PLACENTAL MAMMALS

  11. MONOTREMES • Oviparous=egg laying • 3 species exist today • The Platypus & 2 echidna species • Platypus: -waterproof fur, webbed feet, & flattened tail that aids in swimming -uses its wide, flat, leathery bill

  12. Echidna platypus

  13. MARSUPIALS • Divided into at least 7 orders within super order Marsupalia • Majority live in Australia • Virginia Opossum is the only native marsupial of the US • Opossums & kangaroos • Embryo develops for a short period within the mother’s uterus & then emerges from uterus & crawls into the mother’s pouch • Newborn is only 2-3 cm and attaches to a nipple to feed • Newborn’s development and growth then continue inside the pouch for several months

  14. Opossum Koala • kangaroo

  15. Placental Mammals • Horse, dog, rabbit, bats, monkeys, moles, mice, caribou, zebra, whales, dolphins, manatees, elephants….etc • 95% of mammals are placental mammals • Classified into about 20 orders

  16. Give birth to well-developed young after a long period of development inside the uterus • During development, the placenta provides nourishment & oxygen to the developing offspring • Placenta begins to form shortly after fertilization, when the fertilized egg attached to the lining of the uterus • Nutrients and oxygen diffuse from mother’s blood into the blood of offspring • carbon dioxide and other wastes diffuse from the offspring into the mother’s blood • After birth, infants feed on milk for several weeks or months

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