Final Biodiversity Test

4 defining chordate characteristics (must appear at some point in life cycle)

1. Pharyngeal Gill Slits

2. Dorsal Hollow Nerve Cord

3. Notochord

4. Muscular Post-Anal Tail

Pharyngeal Gill Slits are used for

filter feeding in primitive chordates, gas exchange in aquatic species, In terrestrial vertebrates → develop into structures in head/neck

Dorsal Hollow Nerve Cord develops into

brain, spinal cord in vertebrates

Notochord function

Flexible supportive rod, Runs length of body, Provides support for movement, In vertebrates mostly replaced by vertebral column

Muscular Post-Anal Tail

Tail extends past anus, Used mainly for movement

3 Subphyla of chordates

1. Cephalochordata

2. Urochordata

3. Vertebrata

Cephalochordata Key Traits

• Small marine suspension feeders

• Fishlike appearance

• Retain notochord as adults

• Notochord acts as endoskeleton

• Have all chordate traits as adults

Cephalochordata habitat

Marine sand

Cephalochordata Reproduction

Sexual reproduction only, External fertilization, Separate sexes

Cephalochordata

Intermediate characteristics between invertebrates and vertebrates

Urochordata Key Traits

Marine only, Adults usually sessile, Larvae swim

Urochordata Distinguishing Characteristics

Tunic = polysaccharide outer covering

U-shaped gut

Two siphons

Urochordata Chordate Traits

Larvae:

• notochord

• dorsal nerve cord

• tail

Adults:

• mainly retain pharyngeal slits

Urochordata Reproduction

Sexual and asexual

Vertebrata Synapomorphies

Vertebrae, Cranium, Gene Duplication

Vertebrae

Cartilage or bone structures, Protect spinal cord

Cranium (Skull)

Protects brain

Gene Duplication

Hox/Dlx gene duplication involved in facial/head development

Vertebrate Brain Regions

Forebrain, Cerebrum, Midbrain, Hindbrain,

In Jawed Vertebrates Brain Regions

Cerebellum, Medulla Oblongata

Forebrain

Smell, Contains cerebrum

Cerebrum

Complex thinking, Memory, Processing

Midbrain

Vision processing

Hindbrain

Balance, Hearing

Cerebellum

Coordination, Motor control

Medulla Oblongata

Breathing, Heart rate, Automatic functions

Earliest Vertebrates

~540 million years ago

Marine

Fishlike

Cartilaginous skeletons

Cartilage

Flexible connective tissue, First vertebrate skeleton type

Major Vertebrate Innovations

1. Bony Exoskeleton

2. Jaws

3. Bony Endoskeleton

4. Tetrapod Limbs

5. Amniotic Egg

Bony Exoskeleton

First appeared ~480 mya, Protective plates/scales

Jaw

First jawed fishes ~440 mya, Allowed biting and predation, Huge evolutionary advantage

Jaw Origin

Evolved from anterior gill arches

Evidence

Similar embryonic origin, Similar structure, Derived from neural crest cells

Bony Endoskeleton

Supports movement, Improved swimming ability

Tetrapod Limbs

Appeared ~365 mya, First vertebrates capable of land movement

Tetrapod

four limbed vertebrate

Amniotic Egg

Appeared ~345 mya, Allowed reproduction away from water

Is fish monophyletic?

NO

Is fish paraphyletic?

YES

Jawless Vertebrates

Hagfish and Lampreys

Jawless Vertebrates Traits

Lack jaws, Have craniums

Hagfish

No vertebral column, Scavengers/predators

Lampreys

Small cartilage vertebrae, Ectoparasites

Cartilagionous fishes Includes

Sharks, Rays, Skates

Cartilagionous fishes Key Traits

Cartilaginous skeleton, Jaws, Paired fins

Cartilagionous fishes Reproduction

Internal fertilization

Sharks Important Traits

Torpedo-shaped body, Predators, Acute senses

Buoyancy

Oil-filled liver, Lift from fins

Gas Exchange

Water flows through gills

Special Features of sharks

Lateral line system detects electrical fields, Multiple rows of teeth, Spiral valve increases absorption area

Skates and Rays Traits

Flattened bodies, Bottom dwellers, Eat mollusks/crustaceans

Ratfish/Chimaeras

Deep-water fishes, Eat shrimp/mollusks/urchins, Some have poisonous spine

Actinopterygii

Ray finned fish

Actinopterygii key traits

Fins supported by bony rays, Most successful vertebrate lineage

Teleostei

96% of living fish species,“Bony fish”

Swim Bladder

Gas-filled organ for buoyancy

Reproduction of Actinopterygii

Mostly external fertilization, Oviparous

Lobed finned fish includes

Coelacanths, Lungfish

Lobed finned fish Importance

Closest relatives to tetrapods

Lobed finned fish Key Traits

Fleshy fins, Bone arrangement similar to limbs

Lungfish traits

Can breathe air, Can survive drought, Some “walk” on pond bottoms

Amphibia 3 Clades

1. Frogs and toads

2. Salamanders

3. Caecilians

Amphibia Traits

Ancient tetrapods, Moist skin, Gas exchange through skin

Amphibia Reproduction

Eggs laid in water, Larvae undergo metamorphosis

Caecilians

No limbs, No eyes

Mammalia

1. Monotremata

2. Marsupiala

3. Eutheria

Mammalia defining traits

1. Hair/Fur

2. Endothermy

3. Mammary Glands

Hair, Fur

Insulation

Endothermy

Internal heat production

Mammary Glands

Produce milk

Monotremata

Platypus, Echidnas

Monotremata traits

Lay eggs, Low metabolic rate, Found only in Australia

Marsupials Traits

Short gestation, Young develop attached to nipple, Often inside pouch

Marsupials Important Concept

Convergent evolution with placental mammals

Eutheria Traits

Placenta, Viviparous, Young more developed at birth

Eutheria Important Concept

Most diverse mammals

Reptilia traits

Scales, Well-developed lungs, Amniotic eggs

Two types of skull openings

Diapsids (Reptiles)- 2 skull openings each side

Synapsids (Mammals)- 1 skull opening each side

Diapsids

2 skull openings each side

Synapsids

1 skull opening each side

Reptile Groups

1. Lepidosauria

2. Testudinia

3. Crocodilia

4. Aves

Lepidosauria

Lizards and Snakes

Lizards

Usually legs, Predators/herbivores

Snakes

Limbless, Carnivores, Fangs may inject venom

Testudinia

Turtles/Tortoises

Testudinia Traits

Bony shell, Beak instead of teeth

Crocodilia

Crocodiles/Alligators

Crocodilia Traits

Eyes and nostrils on top of head, Semi-submerged ambush predators

Aves

Birds

Aves Traits

Feathers, Endothermic, Descended from dinosaurs

Flight evolved independently in

1. Pterosaurs

2. Bats

3. Birds

Bird Adaptations for flight

Keel, Hollow Bones, Endothermy

Keel

Sternum projection, Flight muscle attachment

Hollow Bones

Lightweight skeleton

Endothermy

High metabolic activity

Amniotic Egg Membranes

Amnion, Yolk Sac, Allantois, Chorion, Albumen

Amnion

Protective fluid membrane

Yolk Sac

Nutrients

Allantois

Waste storage

Chorion

Gas exchange