Mr. McCloskey Biology II Class Mammalia Mammals

1. Mr. McCloskeyBiology IIClass MammaliaMammals

2. Threatened and Endangered Species of PA www.pgc.state.pa.us/pgc/cwp/view.asp?a=458&q=150321

3. Mammals • Came into being around 200 million years ago – flourished to around 70 million years ago • Although not a large group (approximately 4450 species) it is overall the most biologically differentiated group in the animal kingdom.

4. Mammals • Mammals probably have been influenced by humans more than any other group of animals. • Mammals have been domesticated for clothing, as beasts of burden, and as pets.

5. Mammals • Millions used in biomedical research each year.

6. Mammals • Mammals have been introduced into new habitats (with both positive and negative results)

7. Mammals • Mammals have led to the destruction of habitats for commercial uses.

8. Mammals • Some animals have been greatly over harvested.

9. Characteristics • Body covered with hair (Reduced in some species, especially aquatic ones).

10. Skin with many glands • Sweat glands – not present in any other vertebrates • Scent glands - found in nearly all mammals although functions vary greatly. Used by some species for communication, to mark territory, for warning and for defense.

11. Skin with many glands • Sebaceous glands – sometimes called oil glands • Mammary glands – produce milk for nourishing young.

12. Limbs • Four limbs- (reduced or absent in some) adapted for many forms of locomotion

13. Heart • Four chambered heart with 2 atria and 2 ventricles

14. Warm blooded

15. Teeth • Well developed teeth • Teeth will be adapted for specific diet • 4 types of teeth found in mammals • Incisors = Flat, sharp edges, used for snipping, cutting and gnawing.

16. Teeth • Canines = long and pointed, used for tearing and piercing

17. Teeth • Premolars = compressed square shape, for shearing and slicing

18. Teeth • Molars = Large bodies, squared also, used for crushing and grinding

19. Teeth • Types of teeth present and size will vary according to the animal’s needs. • Most mammals grow just two sets of teeth. • Deciduous teeth • Permanent teeth

20. Teeth • Deciduous teeth = (Milk teeth) – First temporary set.

21. Teeth • Permanent teeth = Grow in when the skull has grown large enough to accommodate a full set (Molars only come in with other permanents – not present in deciduous set)

22. Lungs • Mammals use lungs to breath for their entire life.

23. Highly Developed Brains • Especially well developed in primates. 3 major regions • Cerebrum – Largest portion, controls voluntary functions • Cerebellum – Balance, involuntary actions, muscle coordination • Medulla oblongata – vital body processes such as breathing and heart beat

25. 3 Lines of Mammal Development • 1) Monotremes • Egg-laying mammals – mothers have no nipples • Only 3 species exist – Duck-billed Platypus and 2 spiny Anteaters • They live in Australia, New Guinea and Tasmania

28. Marsupials • Marsupials • Pouched mammals • Give birth to tiny young which are effectively still embryos both anatomically and physiologically • Must crawl to mother’s pouch to complete development • Found mainly in Australia, opossum is the only native North American species

31. Placental Mammals • Most highly evolved animals on Earth • Carry unborn young in the uterus – nourished by the placenta • Materials transferred from mother to unborn young through the umbilical cord • The period of time that young develops in placenta is called the Gestation Period – This will vary from mammal to mammal • (Mouse – 21 days, rabbit 30-60 days, horse – 48 weeks, elephant 22 months)

34. Threatened or Endangered Species • http://www.pgc.state.pa.us/pgc/cwp/view.asp?a=458&q=150321