Chapter 26: Animals – The Vertebrates

Characteristics of Chordates

Bilateral

Some species are invertebrates but the vast majority are vertebrates

Vertebrates – chordates with a backbone and a brain located inside a protective chamber

Chordate – an animal that exhibit the following 4 main features. In many cases these features are temporary, appearing only during embryonic development

4 Features Evident in Chordate Embryos

  1. Notochord – a long rod of stiffened tissue (not cartilage or bone), helps support the body
  2. Nerve Cord – nervous system develops from this tubular structure. Anterior end increases in mass and forms brain
  3. Pharynx – for feeding and/or respiration. Has distinctive slits in the wall
  4. A tail forms in embryos and extends past the anus

Chordate Classification

3 Subphyla of Chordates

  1. Urochordata – tunicates
  2. Cephalochordata – lancelets
  3. Vertebrata

8 Classes of Vertebrates

  1. Agnatha – jawless fish
  2. Placodermi – jawed, armored fish (extinct)
  3. Chondrichthyes – cartilaginous fish
  4. Osteichthyes – bony fish
  5. Amphibian – amphibians
  6. Reptilia – reptiles
  7. Aves – birds
  8. Mammalia – mammals

Invertebrate Chordates

Tunicates

Sea squirts

In marine habitats

Most adults remain attached to rocks

Filter feeders – water flows in siphon and passes through gill slits, and out another siphon

Once sea squirt reaches adult stage its tail and notochord disappear

A very simplified nervous system

Lancelets

Live in nearshore marine sediments around the world

Most of time buried in sand

Lancelet refers to the sharp tapering of their body

Have a closed circulatory system, but no red blood cells

Filter feeders

No brain

Existing Jawless Fishes (Ostracoderms)

Ex. Hagfish and lampreys

75 species

Cylindrical body and a skeleton of cartilage

Hagfish prey on worms or scavenge

Lampreys are parasitic and have a sucker like oral disk

Existing Jawed Fishes (Placoderms)

Vertebrate fish outnumber all other vertebrates

Swim Bladder – an adjustable flotation device that exchanges gases with blood

Scales – small bony plates at the body surface that protect body without weighing it down

Cartilaginous Fishes (Chondrichthyes)

Skates, sharks, rays

Predators

Prominent fins

Skeleton of cartilage

5-7 gill slits

Scales are small

Bony Fishes (Osteichthyes)

Most numerous and diverse vertebrates

Body plans very greatly

3 lineages

  1. Ray-finned fishes
  2. Lobe-finned (1 species remains today)
  3. Lungfish (3 species remain today)

Origin of Amphibians

Lobed finned fish probably pulled themselves up out of dried up ponds to ones that still had water. They gulped air and had lungs

Amphibian – a vertebrate with a body plan and reproductive mode somewhere between fishes and reptiles

Most have largely bony endoskeleton

Four legs

Salamanders, frogs, toads, have not escaped water entirely

Even with lungs or gills, they can use their thin skin as a respiratory surface

Respiratory surfaces must be kept moist

Salamanders

Newts

Like fishes and early amphibians salamanders bend from side to side when they walk

Carnivores

Toads and Frogs

Long hindlimbs and powerful muscles allow them to catapult through the air or water

Sticky-tipped tongue for catching prey

Frogs have mucus and poison glands. Poison types have bright coloration

The Rise of Reptiles

A divergence from the amphibian lineage gave rise to reptiles

First to escape dependency on standing water

Have tough dry scaly skin that restricts loss of water

Fertilization is internal. Sperm do not require free water to reach eggs

Kidneys are good at conserving water

Amniote Egg – egg that has an extra embryonic membranes and often a shell. Embryo develop to an advanced stage before hatching

Early reptiles chased prey with far greater cunning and speed

Limbs were more efficient at supporting the trunk of the body on land

Nervous system increased in complexity

Crocodilians were the first animals with a muscular four-chambered heart fully separated into 2 halves

Reptiles depend on lungs not skin for gas exchange

Crocodilians

Closest relatives of birds and dinosaurs

Live in or near water

Adjust body temperature with behavioral and physiological mechanisms

Like birds in social behaviors when parents guard nests and assist hatchlings into water

Turtles

Live inside shell that is attached to skeleton

Have tough horny plates instead of teeth

Lay eggs on land then leave them

Lizards and Snakes

95% of reptiles

Short-legged long-bodied lizards gave rise to the elongated limbless snake

Some snakes have bony remnants of ancestral hindlimbs

All snakes are carnivores

Snakes usually do not act aggressively toward humans

Tuataras

Have a third “eye”. It can only register changes in daylength and light intensity

Engage in sex after 20 years old

Look like a lizard

Birds (Aves)

Feathers – lightweight structures derived from skin, are used for flight body insulation or both

Birds descended from tiny reptiles that ran about on 2 legs

Feathers evolved as highly modified reptilian scales

Birds have scales on legs

Lay eggs

Differ greatly in body size, proportions, coloration, and capacity for flight

Large durable 4 chambered heart

The Rise of Mammals

Mammals – vertebrates with hair and mammary glands

A few aquatic mammals – whales, dolphins, manatees, platypuses, otters

Care for young for an extended period

Adults serve as model for their behavior

Behavioral Flexibility – a capacity to expand on basic activities with novel forms of behavior

Cerebral Cortex – outermost layer of the forebrain receives, processes and stores information from sensory structures and it issues commands for complex responses

Primates have most highly developed cerebral cortex

Most mammals secure, cut and sometimes chew food before swallowing

Dentition – type, number, and size of teeth differ from reptiles

Have 4 types of upper and lower teeth

  1. Incisors – nip or cut food
  2. Canines
  3. Premolars – crush grind shear
  4. Molars – crush grind shear

Teeth offer clues to life styles

Portfolio of Existing Mammals

3 lineages of Mammals

  1. Monotremes – egg laying mammals
  2. Marsupials – pouched mammals
  3. Eutherians – placental mammals

Spiny anteaters and duck billed platypus are the only living monotremes

Most marsupials are native to Australia

Newborns finish development in a permanent pouch on the mother

Placenta – a spongy tissue of maternal and fetal membranes. Forms inside pregnant females uterus

Grow faster in placenta then in marsupial pouch

Primate Classification

Order Primates – prosimians, tarsioids, anthropoids

Prosimians dominated forests millions of years ago

Anthropoids – monkey, apes, humans

Apes are closer to humans than monkeys in comparing biochemistry

Hominids – humanlike and human species of a line of descent that started with its divergence from apes

Most are arboreal or tree dwellers

5 Trends helped to define lineage leading to humans

  1. Less reliance on sense of smell and more on vision

Eyes are forward directed

Respond to variations in color and light intensity

2. Skeletal changes led to upright walking, which freed hands

Bipedalism – walk on two legs

3. Changes in bones and muscles led to refined hand movements

Opposable thumb led to a precision grip (holding a pen)

  1. Teeth became less specialized
  2. Evolution of the brain, behavior and culture

Parents put more effort in fewer offspring and formed stronger bonds

Language developed

From Early Primates to Hominids

Origins and Early Divergences

Primates evolved from mammals more than 60 million years ago

First ones resembled small rodents

Stayed in trees because abundant food and safety

Climate changed so they had to move out of the trees or die

One lineage gave rise to great apes and other gave rise to the first hominids

The First Hominids

Australopiths – southern apes

Australopiths has a large face, protruding jaws, small skull and brain

Were apelike in many skeletal ways but humanlike in walking upright

Australopithecus afarensis – “Lucy” 3.2 million years old

Emergence of Early Humans

The brain sets humans apart from apes

Earliest humans – Homo habilis means handy human

A great stone tool maker

Homo erectus – means upright man

Clearly related to modern humans

Traveled out of Africa to Europe, Asia

Larger brain

More advanced tool maker

Built fire

Used furs for clothing

Homo sapiens

Means wise man

Evolved 100,000 years ago

Smaller teeth and jaw

Larger brain

Developed complex language

Neandertals

Lived in Europe 200,000 – 30,000 years ago

Massively built and large brain

Their disappearance coincided with the appearance of anatomically modern humans in the same regions about 40,000 – 30,000 years ago.

We have no evidence that they interbred with the later arrivals

Neandertal DNA has unique sequences, so they might not have contributed to the gene pools of modern European populations

We still do not know what happened to them

Humans spread rapidly through the world by devising cultural means to deal with a broader range of environments.

Chapter 26: Animals – The Vertebrates

Characteristics of Chordates

Some species are invertebrates but the vast majority are vertebrates

Vertebrates –

Chordate – an animal that exhibit the following 4 main features. In many cases these features are temporary, appearing only during embryonic development

4 Features Evident in Chordate Embryos

  1. Notochord –
  1. Nerve Cord –
  1. Pharynx –
  1. A tail forms in embryos and extends past the anus

Chordate Classification

3 Subphyla of Chordates

1. Urochordata –

  1. Cephalochordata –
  1. Vertebrata

8 Classes of Vertebrates

  1. Agnatha –
  1. Placodermi –
  1. Chondrichthyes –
  1. Osteichthyes –
  1. Amphibian –
  1. Reptilia –
  1. Aves –
  1. Mammalia –

Invertebrate Chordates

Tunicates

Most adults remain attached to rocks

Filter feeders –

Once sea squirt reaches adult stage its tail and notochord disappear

A very simplified ______system

Lancelets

Live in nearshore marine sediments around the world

Most of time buried in sand

Lancelet refers to the sharp tapering of their body

Have a ______circulatory system, but no red blood cells

Existing Jawless Fishes (Ostracoderms)

Ex.

Cylindrical body and a skeleton of cartilage

Hagfish prey on worms or scavenge

Lampreys are parasitic and have a sucker like oral disk

Existing Jawed Fishes (Placoderms)

Vertebrate fish outnumber all other vertebrates

Swim Bladder –

Scales –

Cartilaginous Fishes (Chondrichthyes)

Bony Fishes (Osteichthyes)

Most numerous and diverse vertebrates

Body plans very greatly

3 lineages

Origin of Amphibians

Lobed finned fish probably pulled themselves up out of dried up ponds to ones that still had water. They gulped air and had lungs

Amphibian –

Most have largely bony endoskeleton

Salamanders, frogs, toads, have not escaped water entirely

Even with lungs or gills, they can use their thin skin as a respiratory surface

Respiratory surfaces must be kept ______

Salamanders

Like fishes and early amphibians salamanders bend from side to side when they walk

Toads and Frogs

Long hindlimbs and powerful muscles allow them to catapult through the air or water

Sticky-tipped tongue for catching prey

Frogs have mucus and ______glands. Poison types have bright coloration

The Rise of Reptiles

A divergence from the amphibian lineage gave rise to reptiles

First to escape dependency on standing ______

Have tough dry scaly skin that restricts loss of ______

Fertilization is ______. Sperm do not require free water to reach eggs

______are good at conserving water

Amniote Egg –

Early reptiles chased prey with far greater cunning and speed

Limbs were more efficient at supporting the trunk of the body on land

Crocodilians were the first animals with a muscular four-chambered heart fully separated into 2 halves

Reptiles depend on ______not skin for gas exchange

Crocodilians

Closest relatives of ______and ______

Adjust body temperature with behavioral and physiological mechanisms

Like birds in social behaviors when parents guard nests and assist hatchlings into water

Turtles

Live inside shell that is attached to ______

Have tough ______instead of teeth

Lay eggs on land then leave them

Lizards and Snakes

______of reptiles

Short-legged long-bodied lizards gave rise to the elongated limbless snake

Some snakes have bony remnants of ancestral hindlimbs

All snakes are ______

Snakes usually do not act aggressively toward humans

Tuataras

Have a third “eye”. It can only register changes in daylength and light intensity

Engage in sex after ______years old

Look like a ______

Birds (Aves)

Feathers –

Birds descended from tiny ______that ran about on 2 legs

Feathers evolved as highly modified reptilian ______

Birds have scales on ______

Differ greatly in body size, proportions, coloration, and capacity for flight

Large durable ______chambered heart

The Rise of Mammals

Mammals –

A few aquatic mammals –

Care for young for an extended period

Adults serve as model for their behavior

Behavioral Flexibility –

Cerebral Cortex –

Primates have most highly developed cerebral cortex

Most mammals secure, cut and sometimes chew food before swallowing

Dentition –

Have 4 types of upper and lower teeth

1.

Teeth offer clues to life styles

Portfolio of Existing Mammals

3 lineages of Mammals

  1. Monotremes –
  1. Marsupials –
  1. Eutherians –

Spiny anteaters and duck billed platypus are the only living monotremes

Most marsupials are native to ______

Newborns finish development in a permanent pouch on the mother

Placenta –

Grow faster in placenta then in marsupial pouch

Primate Classification

Order Primates –

Prosimians dominated forests millions of years ago

Anthropoids –

Apes are closer to humans than monkeys in comparing biochemistry

Hominids –

Most are arboreal or tree dwellers

5 Trends helped to define lineage leading to humans

  1. Less reliance on sense of smell and more on vision

  1. Skeletal changes led to upright walking, which freed hands

Bipedalism –

  1. Changes in bones and muscles led to refined hand movements

  1. Teeth became less specialized
  1. Evolution of the brain, behavior and culture

Parents put more effort in fewer offspring and formed stronger bonds

From Early Primates to Hominids

Origins and Early Divergences

Primates evolved from ______more than 60 million years ago

First ones resembled small ______

Stayed in ______because abundant food and safety

Climate changed so they had to move out of the trees or die

One lineage gave rise to great apes and other gave rise to the first hominids

The First Hominids

Australopiths –

Australopiths has a large face, protruding jaws, small skull and brain

Were apelike in many skeletal ways but humanlike in walking upright

Australopithecus afarensis –

Emergence of Early Humans

The brain sets humans apart from apes

Earliest humans – Homo habilis means ______

Homo erectus – means ______

Clearly related to modern humans

Traveled out of Africa to Europe, Asia

More advanced tool maker

Homo sapiens

Means

Evolved ______years ago

Developed complex language

Neandertals

Lived in ______200,000 – 30,000 years ago

Their disappearance coincided with the appearance of anatomically modern humans in the same regions about 40,000 – 30,000 years ago.

We have no evidence that they interbred with the later arrivals

Neandertal DNA has unique sequences, so they might not have contributed to the gene pools of modern European populations

We still do not know what happened to them

Humans spread rapidly through the world by devising cultural means to deal with a broader range of environments.