Amphibians and Mammals

Objective 4.01 & 4.02: Analyze the classification of organisms & processes by which organisms accomplish essential life

functions.

What does the word “Amphibian” mean?• The word Amphibian means “dual life”.• Amphibians spend the first part of their life in

the water and the second part of their life on land.

General Characteristics of Amphibians Amphibians have the following general

characteristics:• Lay eggs in water• Ectotherms (Cold blooded)• Have 4 limbs• Skin is moist and covered with mucus.

Amphibian Circulatory System

• Closed circulatory system• 3 chambered heart

Amphibian Digestive System• Complete digestive system– Two openings : Mouth and anus– Food moves in one direction: Mouth Anus

Amphibian Respiratory System• Gills as tadpoles• Lungs as adults• Skin must be moist for gas exchange (O2 and CO2)

Amphibian Nervous System

• Have a brain, spinal cord and nerves

Amphibian Reproductive System• Sexual reproduction• External fertilization– Female lays eggs, male

releases sperm• Undergo metamorphosis• Must occur in water

Amphibian Examples

Mammals

General Characteristics of Mammals

• Body covered with hair or fur• Produce milk for young in mammary gland

Mammalian Circulatory System• Closed circulatory system• 4 chambered heart = no mixing of blood

Mammalian Digestive System• Complete digestive system– Two openings : Mouth and anus– Food moves in one direction: Mouth Anus

Mammalian Respiratory System• Use lungs

Mammalian Nervous System• Have a brain, spinal cord and nerves

Mammalian Reproductive System

• Internal fertilization• Three groups 1. Placental mammals – young develop in

uterus2. Monotremes – lay eggs3. Marsupials – give birth to live young that

further develops in pouch

Placentals, Monotremes and Marsupials