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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)