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Kingdom AnimaliaPhylum Chordata

The vertebrates and their relatives

Phylum Chordata

• Characteristics of a chordate

– A dorsal hollow nerve cord (spinal cord in

vertebrates)

– A notochord (most vertebrates only have a

notochord during development – becomes the

backbone in vertebrates)

– Pharyngeal Pouches (develop into gills in fish

and amphibians)

– Muscular Tail (disappears in humans)

Subphylum Cephalochordata

• Amphioxus (Lancelet): live in the ocean with their body

buried in sand

– Have a definite mouth and no jaws

– Long pharynx with up to 100 gill slits

– Breathe through their body surface

– Have a simple digestive system, heart, and closed

circulation

– Use paired muscles to move

Subphylum Vertebrata

• 99% of chordates are vertebrates

– Fish 24,000 species

– Amphibian 4,000 species

– Reptiles 6,000 species

– Birds 10,000 species

– Mammals 4,500 species

Fishes

• Aquatic vertebrates characterized by:

– Fins (Movement)

– Scales (Protection)

– Gills (Breathing)

• There are fish with exceptions!

– Can you name any?

Fish Evolution

• Fish were the first vertebrate to evolve

• Evolved about 540 mya

– Were jawless and covered in armored plates

• Devonian Period = Age of the Fishes

– Fish developed both jaws and fins at this time

Body Systems of Fishes

• Fish feed in a variety of ways including parasites, carnivores, herbivores, etc.

• Most fish breathe using gills– Gills are feathery filaments containing a network of capillaries to

increase surface area for CO2 and O2 exchange

• Fish have closed circulation

Fish Senses

• Fish exhibit cephalization

• Many fish have Chemoreceptors for an extraordinary sense of taste and smell

• Lateral Line System –allows fish to sense movement and vibration

Groups of Fishes

• Class Cephalospidomorphi – lamprey

• Class Myxini – hagfishes

• Class Chondrichthyes – cartilaginousfishes

• Class Osteichthyes – bony fishes

Lamprey and Hagfishes

• Are jawless fishes

– Have mouths of soft tissue and no true teeth

• Have no bones

• Are the only vertebrates that do not have vertebral columns as adults

Lamprey

• Are filter feeders as larvae and parasites that suck blood and tissues of fish as adults

Cartilaginous Fishes

• Includes sharks, rays, skates, sawfishes, and chimaeras

• “Chondros” = Greek word for cartilage

• A typical shark has 3000 teeth arranged in 6 to 20 rows

• Not all are carnivores, the largest sharks are filter feeders

• Some have flat teeth for crushing mollusks and crustaceans

Shark

Ray

Skate

Sawfish

Chimera

Bony Fishes

• Skeletons are made of calcified bone

• Includes fish we are most familiar with: Sunfish, Perch, Northern Pike, Walleye, Smallmouth Bass, etc.

Fish Ecology• Some fish can live in both salt water and fresh water

Catadramous Fishes –spend most of their life in fresh water but move to the ocean to breed

Anadromous Fishes –spend most of their life in the ocean but move to fresh water to breed

Class Amphibia

• Amphibians gave rise to all other land vertebrates

• Amphibian means “double life”

– As larvae they are typically aquatic filter

feeders or herbivores breathing through gills

– As adults most species are terrestrial

carnivores that breathe through their moist

skin and have lungs

Adaptations to Life on Land

• As the amphibians developed in the late Devonian Period 360 mya they needed to adapt to terrestrial life– Keep from drying out

– Breathe using lungs, not gills

– Bones in limbs allow movement

– Ribs to support and protect internal organs

• Amphibians dominated the Carboniferous Period 345 to 285 mya

Amphibian Body Systems• Amphibians have a well developed

digestive system similar to that of humans

• As most amphibians develop lungs as adults, some are lung-less and only breathe through their skin

• They have closed circulation and a 3 chambered heart with a double loop system similar to that of a human

• Ammonia is disposed of in urine through the use of kidneys

Amphibian Reproduction

• Most amphibians lay their eggs in water; fertilization is external

• Some salamanders fertilize internally

Amphibian Senses

• Amphibians have a well developed brain and spinal cord similar to that of a fish

• Eyes are protected by a nictitating membrane

• A tympanic membrane, or eardrum, is located on either side of the head

• Many have a lateral line system similar to that of a fish

Groups of Amphibians• Order Urodela: Salamanders and Newts

• Order Anura: Frogs and Toads

• Order Caudata: Mudpuppies

• Order Apoda: Caecilians

Amphibian Ecology

• Most are a great meal for birds and reptiles

• Some have toxins to poison predators

• Some have bright colors to warn of their toxins

• Some mimic the bright colors of others and are harmless

Amphibian Ecology

• Amphibian populations are declining worldwide due to several factors:– Global Warming

– Decreasing Habitat

– Depletion of the Ozone

– Water Pollution

– Introduced Aquatic Predators

– Fungal Infections

– Increasing human population!

Class Reptilia

• Land vertebrates with a well developed skull, a backbone and tail, and four limbs

– Exceptions: snakes have no legs, and turtles

have a shell formed of fused vertebrae

• Can a turtle lose its shell?

Reptile Evolution

• The oldest reptile fossils date back to the early Carboniferous Period some 350 million years ago

• Dinosaurs of the Triassic and Jurassic Period ruled the earth until 65 million years ago

Reptile Body Systems

• Reptiles are ectotherms – rely on interactions with the environment to control their body temperature

• Reptiles have well developed lungs, four chambered hearts, and a well developed brain and spinal cord

• Reptiles’ legs are rotated farther under their body than amphibians allowing them to carry weight and walk on land more efficiently

Reptilian Eggs

• Reptiles have amniotic eggs – named after one of the four membranes around the developing embryo

– Amnion: produces watery environment

around embryo

– Yolk Sac: contains nutrient rich yolk that

feeds embryo

– Chorion: allows gas exchange

– Allantois: stores waste

Groups of Reptiles

• Order Squamata: lizards and snakes

• Order Crocodilia: alligators, crocodiles, caimans, and gavials

• Order Chelonia: turtles, tortoises, terrapins

• Order Rhynchocephalia - tuataras

Class Aves

• Characteristics of

most birds

– Maintain a constant

internal body

temperature

– Covered in feathers

– Have two legs for

walking and perching

– Front limbs are wings

– Most are adapted for

flight

Evolution of Birds

• Oldest known fossil is Archaeopteryx which lived during the Jurassic Period 150 mya.

– Had teeth in its beak, a jointed tail, and toes

and claws on its wings

• Birds are very closely related to dinosaurs, but scientists disagree on whether birds evolved from dinosaurs – or- birds and dinosaurs evolved from one common ancestor

Body Systems of Birds

• Endotherms: can generate their own body heat; warm-blooded

• Smaller birds must eat more in relation to its size due to Surface Area to Volume Ratio

Senses of Birds

• The brains of birds are very well developed

– Birds can see color very well

– Birds can hear very well

– Smell or taste are not well developed

Eggs and Incubation

• Eggs are amniotic but unlike reptile eggs have a hard outer shell

• Eggs must be incubated by the parents since they are endotherms

• Young must be cared for after hatching

Groups of Birds

• There are nearly 30 different orders of birds

• 60% of all birds worldwide are perching birds

Class Mammalia

• Characteristics of mammals

– Endotherms

– Have mammary glands and nurse young

– Have hair

Evolution of Mammals

• The earliest mammals evolved about the same time as the early dinosaurs but remained in the shadows until the giant reptiles disappeared

• First ancestors of mammals appeared during the Permian Period about 290 to 250 mya

• First true mammals appeared during the Jurassic Period 210 mya

Juramaia – 160 mya; China

Megazostrodon – 200 mya; Southern Africa

Purgatorius – earliest primate ancestor; 66 mya; North America

Staying Warm

• Animals have hair to help insulate their bodies.

• They also have subcutaneous fat to keep them warm and many have sweat glands to cool them off.

• Smaller mammals have higher metabolism than larger ones in order to create enough body heat to keep warm.

• Mammals eat about 10 times as much food as a reptile in order to stay warm.

Comparison of Vertebrate

Forelimbs

• When comparing the bones and bone structures of all vertebrates - birds, amphibians, reptiles, and mammals – you can see many of the same bones with very similar functions

Mammal Reproduction

• Internal Fertilization occurs in mammals

• Mammals are divided into three groups based on methods of development and birth

– Oviparous: egg-laying mammals are called

monotremes

– Viviparous: includes both placental mammals

and marsupials

Caring for Young

• All newborn mammals feed on their mother’s milk

• Some newborns are helpless at birth and must be cared for

• Others are able to see and walk within minutes after birth

Orders of Mammals

• There are 12 orders of placental mammals

• They are classified based on several criteria including

– Feeding

– Teeth and Jaw Structure

– Foot Structure

– Brain Development

First Life: 3.8 bya

First Fish: 518 mya

First Multi-cellular life: 2.5 bya

First Amphibian: 370 mya

First Reptile: 315 mya

First Bird: 150 mya

First Mammal: 195 mya

First Primate: 66 mya

First Modern Human: 0.00016 mya(160,000 years)