Vertebrate Structure and Function

Part 1 - Comparing Structure and Function

Classification of Vertebrates

a. Phylum: Chordata Common Characteristics: Notochord, pharyngeal gill slits,

hollow dorsal nerve cord

b. Sub-phylum: Vertebrata Common Characteristics: Backbone that supports and

protects spinal cord, endoskeleton, distinct head with skull and brain

Part A: Overview of Vertebrate Classes

1. Vertebrate Class Definitions

a. Fish - aquatic vertebrates that are characterized by scales, fins and pharyngeal gills. There are 3 main groups: jawless, cartilaginous and bony. Ex. Lamprey, dogfish shark, perch.

b. Amphibians - vertebrates that are aquatic as larvae and terrestrial as adults. They breathe with lungs as adults, have a moist skin with glands and lack scales and claws. Ex. Frog, salamander, newt.

c. Reptiles - vertebrates that have lungs, scaly skin and a special type of egg (amniotic). They live entire life out of water. Ex. Snake, lizard, turtle.

d. Birds - endothermic, reptile-like vertebrates with feathers, two legs used for walking and perching and wings that usually don’t have claws. Ex. Pigeon, hawk, eagle.

e. Mammals - endothermic animals with fur or hair, and mammary glands that produce milk to nourish young. Almost all give birth to live young. Ex. Human, whale, fetal pig.

Part B: Important Evolutionary Advances

a. Jaws in Fishes

• Fish are considered to be the most primitive living vertebrate.

• The first fishes to be found in abundance in the fossil record were jawless. These are limited to eating small particles of food by filter-feeding and vacuum suction.

• The evolution of jaws in fishes made it possible for them to eat plants and other animals and defend themselves by biting.

b. Strength of Skeleton in Amphibians

• Amphibians probably evolved from lobe-finned fishes. These organisms faced many challenges transitioning from water to land.

• The first amphibians had strong limb bones and girdles for movement unsupported by water.

• The ribs formed a cage that supports and protects the internal organs.

c. Eggs in Reptiles

• Reptiles evolved from amphibians when climatic changes caused destruction of amphibian habitat. These organisms had to survive their entire lives on land.

• Reptilian eggs are surrounded by a shell and several membranes that create a protected environment for the embryo.

• These “amniotic eggs” contain nutrient-rich yolk used by the embryo for food.

d. Temperature Control in Birds and Mammals

• Fish, amphibians and reptiles are ectothermic. The have an internal body temperature that varies with external (environmental conditions) due to a slow metabolism.

• Birds and mammals are endothermic. They maintain a relatively high and constant internal body temperature that is regulated internally due to a fast metabolism.

• This adaptation is very important for animals living in habitats where temperatures and seasons are variable.

Part C: Comparing Structure and Function Among Vertebrates Feeding and Digestion

a. Jaws and Teeth

Part C: Comparing Structure and Function Among Vertebrates Feeding and Digestion

a. Jaws and Teeth

Feeding and Digestion

b. Digestive Systems

Respiration

a. Lungs

Respiration

Fish

Circulation/Internal Transport

a. Heart Chambers and Circulatory Systems

Reproduction

a. Definitions

• Oviparous: a vertebrate that lays eggs that develop outside the mothers body

• Ovoviviparous: a vertebrate whose young develop inside the mother’s body but are not nourished directly by the mother’s body.

• Viviparous: a vertebrate who bears live young and directly nourishes the unborn young by the mother’s body.

b. Fertilization

• External: eggs are fertilized outside the mother’s body.

• Adults release eggs and sperm into the surrounding water and sperm swim to the eggs to fertilized them.

• To increase chances, huge numbers of eggs and sperm are released.

• Internal: eggs are fertilized inside the mother’s body.

• Sperm is deposited into the body of the female.

• This makes it possible for the female’s reproductive system to cover the embryos with protective membranes and a shell after fertilization.