Lesson 3-2 All vertebrates have a backbone— a series of structures that surround and protect the...

• All vertebrates have a backbone—a series of structures that surround and protect the nerve cord, or spinal cord.

• The spinal cord connects all the nerves in the body to the brain.

• Bones that form a backbone are called vertebrae.

Characteristics of Vertebrates

• Vertebrates have well-developed organ systems.

• All vertebrates have digestive systems with 2 openings, closed circulatory systems that move blood through the body, and nervous systems that include brains.

• The five major groups of vertebrates are fish, amphibians, reptiles, birds, and mammals.

Characteristics of Vertebrates (cont.)

• Fish spend their entire lives in water and have two important characteristics in common: gills for absorbing oxygen gas from water and paired fins for swimming.

Fish

• Hagfish and lampreys lack jaws and are in a group called jawless fish.

Fish (cont.)

https://www.youtube.com/watch?v=tKTRv3hx1s0

https://www.youtube.com/watch?v=9JQ6oHjpeqU

• Sharks, skates, and rays are cartilaginous fish with skeletons made of a tough, fibrous tissue called cartilage.

Fish (cont.)

• Store oil in liver to stay afloat

– Still denser than water and need to keep moving to stay afloat

• Some must swim to maintain the flow of water over their gills

– If they stop swimming, they will suffocate

• Others do not have to swim

– They can lie on the ocean floor and pump water across their gills

Cartilaginous Fish

Fish (cont.)

Trout, guppies, perch, tuna, mackerel, and thousands of other species do not have cartilaginous skeletons. They have bones and are grouped together as bony fish.

• Frogs, toads, and salamanders belong to the class Amphibia.

• Most amphibians spend part of their lives in water and part on land.

Amphibians

amphibian

from Greek amphi–, means “of both kinds” and bios, means “life”

Young amphibians live in water and have gills and fins. Through metamorphosis, most adults develop lungs and limbs and live on land, near water.

• Lay eggs in water. These eggs do not have hard protective coverings, or shells.

• No scales

– Skin is thin, smooth, and moist

• Don’t drink water

– Absorb it through their skin

Amphibians (cont.)

• Lizards, snakes, turtles, crocodiles, and alligators belong to the class Reptilia.

Reptiles

• All reptiles have waterproof skin that is covered in scales.

Reptiles (cont.)

• Like amphibians, most reptiles have three-chambered hearts.

Reptiles (cont.)

• Unlike amphibians, lizards and other reptiles have lungs throughout their lives.

• Most reptiles lay fluid-filled eggs with leathery shells that they lay on land.

Reptiles (cont.)

• Warm blooded

(Endotherms)

Endothermic: Warmblooded(Birds and Mammals)

• All birds are in the class Aves.

• Birds have lightweight bones, skin covered with feathers and scales, two legs, and two wings.

Birds

Many birds can fly, and they have stiff feathers that enable them to move through the air.

Birds (cont.)

• Birds have toothless beaks and digestive systems that include gizzards, organs that help grind food into smaller pieces.

Birds (cont.)

• Birds lay fluid-filled eggs with hard shells and feed and care for their young.

Birds (cont.)

• Birds have many characteristics in common with reptiles and are thought to be descendants of dinosaurs

Birds (cont.)

BIRDS

• Share some characteristics with reptiles

– Vertebrates

– Legs and feet covered by thick, dry scales

– Skin around beak is scaly

– Amniotic egg

• High metabolism to get energy to fly

• Eat large amounts of food in proportion to body weight

• Large eyes

• Air sacs – increase amount of oxygen taken in

• Rapid heart rate - muscles get more oxygen from blood

• Hollow bones

• Powerful flight muscles attached to a keel

Birds have many Adaptations for flight

• Dogs, cats, goats, rats, seals, whales, and humans are among the many vertebrates belonging to the class Mammalia.

• All mammals have hair or fur covering their bodies.

• Mammals tear and chew their food using teeth.

Mammals

• The most notable characteristic of mammals is the presence of mammary glands that produce milk which feeds young mammals.

• Mammals are grouped according to how their young develop.

Mammals (cont.)

Placental Mammals

– Develop inside mother’s uterus

– Attached to mom by a placenta-an organ that transfers oxygen, nutrients and waste

– Give birth to completely developed live young

• Just 2 species alive today

– Echidna

• Spine-covered with long snouts

• Long sticky tongue for catching ants & termites

– Platypus

• Swimming mammal

• Lives and feeds in rivers and ponds

• Webbed feet, flat tail, flat, rubbery bill to dig for food and to dig long tunnels to lay eggs

Monotremes- mammals that lay eggs

– Mammals with a pouch

– Give birth to live young

– Shortly after birth- drag themselves through mother’s fur until they reach a pouch in her abdomen

– Mammary glands are located inside pouch

Marsupials

Marsupials cont’

Young Kangaroos (Joey) climbs in, latches onto a nipple, and drinks milk