Chordates Flashcards
Phylum of chordates
Chordata
Four defining characteristics of juvenile chordates
Hollow dorsal nerve cord Notochord Pharyngeal cleft Post anal muscular tail Muscle segments
What is the notochord
Cartilaginous rod
What is the pharyngeal cleft
Slots between the mouth and stomach held open by cartilaginous rod
What is the common ancestor of chordates
Cephlachordata
How do cephalochordata feed
Filter feed using a mucous net
Release mucous into the water as currents waft plankton passes. Plankton gets stuck in mucus and then the mucus is ingested with the plankton
How do Urochordata feed
Sucks in water and use pharyngeal slots to filter out food and release water
What are tunicates
Urochordata
What are lancelets
Cephalochordata
Explain the 2R hypothesis
The genome of jawed vertebrates has been shaped by two rounds of whole genome duplication that took place after the emergence of Urochordata but before the emergence of jawed vertebrates
How many species of vertebrate chordates
66000
Differences between cephalochordata and vertebrates
Vertebrates have: Large brain Skull Eyes Teeth
How many years ago did vertebrates evolved
550 MYA
What is a myxini
Hagfish
How do myxini eat
Tie themselves on a knot
Push knot up body
Motion helps rip flesh off prey
What does agnathans mean
Without jaw
Describe the structure of a hagfish
Agnathans
Cartilaginous skeleton
Well developed notochord
What is a petromyzontida
Lamprey
How many species of lamprey
35
How do lamprey larvae feed
Filter feeders
How do adult lamprey feed
Parasitic or do not feed
Describe the structure of a lamprey
Notochord
Simple vertebral column
Mineralisation along notochord - shows segments
What are actinopterygii
Fin fish
What are the three classes of actinopterygii
Chondrostei
Holostei
Teleostei
What are chondrostei
Sturgeons
Paddlefish
What are holostei
Gars
Bowfin
What are teleostei
Ray finned
How many species of chondrostei
45
How many species of holostei
9
How many species of teleostei
27000
Characteristics of actinopterygii
Ossified endoskeleton - bones Skin covered in scales and mucus Swim bladder External fertilisation - produce lots of eggs Pelagic larvae hatch from eggs Some show parental care
Characteristics of teleosts
Find supported by rays
Jaw modifications
How do actinopterygii change how much they float
Change the amount of gas in their swim bladder
What type of reproduction do guppies show
Ovoviviparous
What type of reproduction do tile perch show
Viviparous
What is an actinistia
Lobe finned fish
What are the two living species of actinistia
Coelacanth
Latimeria
Characteristics of actinistia
Hinges skull
Ovoviviparous
Fleshy fins
When were actinistia discovered
1938
After 80 million year absence
What is a dipnoi
Lungfish
What is the closest living relative to tetrapods
Dipnoi - lungfish
Where do lungfish live
Swamps and shallow pools
Can crawl through wet vegetation from one pool to another if the pool dries out
How do lungfish breath
Gulp air into lungs
How are Osteichthyes characterised
By jaws and mineralised skeletons
When did vertebrates evolves
In the Cambrian
When did dipnoi evolve
In lower Devonian
what are the advantages of jaws
allows efficient feeding
wider range of food can be eaten
what were jaws derived from
cartilaginous structures
what 4 clades have jaws
Chondrichthyes
Placoderms†
Acanthodians†
Osteichthyes
what are Chondrichthyes
sharks etc
how many species of elasmobranchii
1150
how many species of holocephali
50
what orders make up the chondrichthyes
elasmobranchii
holocephali
what are elasmobranchii
sharks
skates
rays
what are holocephali
chimeras
how do chondrichthyes float
liver filled with oil - oil floats on top of water
what is negative bouyance
means they can float on the sea bed
characteristics of chndrichthyes
cartilaginous skeleton reinforced with small bone plates
no swim bladder
carnivores
well developed sense of smell and lateral line system
well developed jaws and paired fins
internal fertlisation
few offspring
how do dogfish reproduce
ovipary
how do bronze whaler sharks reproduce
vivipary
how do sharks reproduce
vivbrous
male uses pelvic fin to transfer sperm to female
eggs fertilised
female gives birth to live young
How did the limbs of tetrapods evolve
From the fina of lobe finned fish
How old are amphibians
375 MYA
What tetrapods include
Amphibians
Amniotes
mammalia
When did mammals and birds radiate
Tertiary - 65 MYA
When did dinosaurs become dominate
Cretaceous- 135 MYA
When did birds evolve
Jurassic - 192 MYA
When did the first amphibians evolve
Devonian - 410 MYA
When did the first reptiles evolve
Carboniferous- 350 MYA
When did reptiles radiate and amphibians decline
Permian - 290 MYA
When did the first dinosaurs evolve
Triassic - 230 MYA
What are the three orders of amphibia
Urodela
Anura
Apoda
What are urodela
Beets and salamanders
What are Anura
Frogs and toads
What are apoda
Caecilians
How many species of urodela
650
How many species of Anura
6200
How many species of apoda
190
Characteristics of amphibians
Thin skin with limited keratinisation Skin permeable to oxygen and water Most restricted to damp environments Fertilisation generally external Eggs have no shell Fish like larvae
What are the results of amphibian eggs having no shell
Prone to desiccation and need physical support
Describe the larvae of amphibians
No legs No lungs Have gills Aquatic herbivores Lateral line system
Describe adult amphibians
Terrestrial carnivores
4 legs
Lungs
When did amniotes evolve
In the Carboniferous
What four specialised membranes make up an amniotic egg
Amnion
Allantois
Yolk sac
Chorion
What do the four specialised membranes of amniotic eggs allow
Protection from desiccation
Gas exchange
Store food and waste
What is desiccation
State of extreme drying out
What does the specialised amniotic egg allow amniotes to be
Truly terrestrial
What is the oldest known amniote
Hylonomus
What is older than hylonomus and may be an amniote
Westlothiana
How old is hylonomus
312 MYA
How old is westlothiana
338 MYA
What are the two main classes of amniotes
Reptilia
Mammalia
What is an ondotochelys semitestacea
Toothed turtle with a half shell
Where is the shell on odontochelys
Underside
How old are odontochelys
220 MYA
What are testudines
Turtles
How many species of testudines
327 species
What reptilian characteristics are shown by Testudines
Skull morphology
Scales of beta keratin
Internal fertilisation but lay eggs
Ectothermic
What are crocodilia
Crocodiles and alligators
How many species of crocodilia
24
Crocodilia have a secondary palate - what does this mean
Can breathe from their nose and mouth
Why do people believe archaeopteryx was the first bird
Has a mixture of reptilian and avain characteristics
From Jurassic period about 150 MYA
How many species of birds
10000
How many orders of birds
23
Characteristics of birds
Beta keratin feathers Large, keeled sternum Fore-limbs modified for flight Hind limbs for bipedal walking Internal fertilisation but lay hard shelled eggs Endothermic
What is the only species in the class sphenodontia
Lizard like carnivorous reptile
Where was the only species of sphenodontia found
Island off of New Zealand
Why is there only one species in the class sphenodontia
Most went extinct 65 MYA
How does the one species of sphenodontia differ from lizards
Different skull but has ancestral features
What are Squamata
Snakes and lizards
How many species of Squamata
9800
Characteristics of snakes
Limbless
Elongate
Modified jaw and skull
What is a hadrocodium wui
Mammal
When was hadrocodium evolved
195 MYA - early Jurassic
Describe the hadrocodium wui
Large brain
Malleus and incus in ear
How many species of mammalia
5450
Characteristics of mammals
Alpha keratin hair Specialised teeth Articulation of jaw between dentary and squamosal bones Endothermic Internal fertilisation Amniotic eggs Mammary glands