MAMMALS DR. U P K EPA DEPARTMENT OF ZOOLOGY & ENVIRONMENTAL MANAGEMENT
Course code : ZOOL 1201 Learning outcomes of this lecture series: At the end of this course, the student will be able to describe the diversity of form and function of mammals and discuss their evolutionary trends Class Mammalia Includes 4000 species Most dominant land animals on earth.
Key Characteristics of Mammals All mammals have the following in common: Are endothermic Hair Specialized teeth Females produce milk in mammary glands to nourish live young
Mammals and Hair Mammals are the only animals that have hair
Primary function of hair is insulation Other functions of hair include: Helping animals blend into their surroundings Using its hair for advertising Black and white hair on a skunk warns predators to stay away Specialized hair serve as a sensory function Whiskers on cats and dogs are sensitive to touch
Endothermy Mammals are endothermic (warm-blooded) Are animals that can maintain a constant body temperature despite the changes in the environment Endothermy allows animals to live in cold environments
Endothermy Endothermy enables mammals to be very active Movement for long periods of time requires a lot of energy and a high metabolism A mammal needs to eat 10x as much food as an ectotherm of similar sizes Metabolizing food requires a lot of oxygen
Endothermy The respiratory and circulatory systems of mammals are adapted to endothermy They acquire and distribute oxygen more efficiently than the respiratory and circulatory systems of ectoderms do
Respiratory System Mammal lungs have a larger surface area than reptiles and amphibians Mammals can exchange more oxygen and carbon dioxide in each breath
Respiratory System The Diaphragm aids mammals in breathing The diaphragm is a sheet of muscle that separates the chest cavity from the abdominal cavity When the diaphragm contracts, the chest cavity enlarges and air is drawn into the lungs
Circulatory System Mammals have a four-chambered heart A septum completely divides the ventricle The left ventricle pumps oxygen-rich blood to the body The right ventricle pumps oxygen-poor blood to the lungs Only the oxygen-rich blood is delivered to the tissues
Specialized Teeth Mammals eat many types of food Mammals have specialized teeth that reflect the difference in their diets Mammalian teeth are continually lost and replaced Mammalians usually only have two sets of teeth Baby Teeth = the first set Permanent Teeth = the second set (not replaced)
Types of Teeth Most mammalians have four types of teeth Each type of tooth performs a different function 1. Incisors - Biting and cutting (Front teeth) 2. Canines - Used for stabbing and holding (behind incisors) 3. Premolars Crushing and grinding (line the jaw) 4. Molars- Crushing and grinding (line the jaw)
Mammals have single lower jaw
Three auditory osscilces
Parental Care Young mammals depend on their mother for a relatively long period of time They receive milk and other food Milk is produced in the mammary glands, which are located on the female s chest or abdomen Protection shelter
Parental Care All mammals reproduce by internal fertilization Mammals differ in how and where their fertilized eggs develop Mammals are classified into three groups based on their pattern of development 1. Monotremes 2. Marsupials 3. Placental Mammals
Movement Mammals use various modes of locomotion, including running, hopping, climbing, flying, burrowing, and swimming Adaptations in body structure help mammals move around in their particular environments
Response Mammals rely on their senses- vision, hearing, smell, taste, and touch- for survival The importance of a given sense depends on the animal s lifestyle Example: Bats and Dolphins live in different locations but both use echolocation Echolocation is the process of using reflected sound waves to find objects
Answer the following What are three functions of hair? Why does a mammal need to eat more food than a reptile of similar size? What type of tooth is used for stabbing a holding? What group of mammals lay eggs? What are the types of locomotion that mammals use?
Class Mammalia Subclass Prototheria- extinct mammals with unique skull structure Subclass Theria- Living mammals distinguished by skull Infraclass Ornithodelphia- Monotremes Infraclass Metatheria- Marsupials Infraclass Eutheria- Placentals
Classification: Class: Mammalia: Subclass: Prototheria Theria Theria Infraclass: Ornithodelphia Metatheria Eutheria Order: Monotremata Marsupialia 19 orders 12
Order Monotremata Oviparous or egg laying mammals Only 3 in existence Duck-billed platypus and two species of spiny anteaters called echidna. Not completely endothermic (their body temperature is lower and fluctuates more than other mammals)
Mammary glands without nipples Edentulous as adults; No teeth Limbs modified for swimming or digging Australia and New Guinea
Duck-Billed Platypus Ornithorhynchus Only member of the mammal family Ornithorhynchidae Several reptilian characteristics: same opening for reproduction and eliminating waste products, the ability to lay eggs The world's only venomous furred animal Spur on hind foot Females loose after one year Bill contains an electro-receptor system 30
WHAT ARE THE ADAPATATIONS SEEN IN THE HEAD OF PLATYPUS FOR AQUATIC MODE OF LIFE?
THIS PICTURE SHOWS THE HIND LEG OF MALE PLATYPUS. IDENTIFY AND STATE THE FUNCTION OF THE RED COLOURED ORGAN.
POISON LAND THICK, WATER PROFF FUR KEEPS EYES, EARS & NOSTRILS SHUT ELECTRO RECEPTORS SINGLE OPENING FOR ANUS & URINO- GENITAL SYSTEM LAYS EGGS WEBBED FEET TOOTHLESS MOUTH & BEAK
LIFE OF PLATYPUS
World's Strangest Creature? Part Mammal, Part Reptile
Platypus is a Predator of: Small frogs Insects Worms Cray fish Prey of: Tasmanian devils Crocodiles Sharks
Echidna (Spiny Anteater) Tachyglossus aculeatus "Echidna" derives from the Latin word for "viper Tongue protrudes like a snake Nocturnal Terrestrial and burrowing They have very tough spines that cover the top of the body.
Can you tell the adaptations seen for terrestrial mode of life? What do you think of its hair distribution?
Echidnas are solitary animals and live in burrows. When attacked, the echidna will quickly burrow into the ground or curl up into a ball.
Lactation goes for A single egg is laid in a pouch that sticks to the mother s belly. Baby echidnas are born blind and hairless. Young suckle in the pouch for about 55 days which is when they start getting too prickly!
Echidna spines are very long. They also have long, sharp claws on the feet and a very sensitive snout. There are 2 types of echidna: long nosed and short nosed.
Echidnas are insectivores. They use their long, sticky tongue to catch ants, termites, other insects, and earthworms.
What are the adaptations of insectivorous mammalas?
See the Claws..
Endangerment Hunted with trained dogs. Loss of natural forest habitat due to farming.
How can the echidna be conserved? Prohibit hunting. Establish wildlife reserves for them.