Fishes, Amphibians And Aminotes Flashcards
What are the characteristics of a fish
Vertebral column
Specialised sense organs
Internal gills
Paired fins
Jaws with teeth
What are the two classes of jawless fish
Hagfish
Lampreys
What are the characteristics of a hagfish
Lack Jaws, paired fins and scales
Cartilaginous skeleton
5-16 pairs of gills
Dorsal nerve cord with differentiated brain (but no cerebellum)
Biting mouth with two rows of teeth
What are the characteristics of lampreys
Lack jaws, paired fins and scales
Complete cartilaginous skull and vertebrae
Dorsal nerve cord with differentiated brain and cerebellum
Sucker like oral disk with teeth
What are the benefits of jaws
Stronger teeth
Muscular attachment points
Can eat larger things
How did jaws evolve
Jaws are thought to have evolved from the anterior gill arches of fish. Front pair of gill arches fused at the top and bottom forming hinges and then scales lining the mouth formed teeth.
What are placoderms
Armoured fishes present in the Devonian
What are the two classes of jawed fishes
Chondrichthyes
Osteichthyes
What are the characteristics of chondrichthyes
Cartilaginous endoskeleton
Dermal placoid scales or naked skin
Generally exposed gills
Ventral mouth
Heterocercal tail
Oily liver for buoyancy
Internal fertilisation
What are the characteristics of Osteichthyes
Bony endoskeleton
Epidermal cycloid scales
Gills covered by operculum
Anterior mouth
Homocercal tail
Swim bladder for buoyancy
External fertilisation
How do Chondrichthyes have an improved jaw design
Upper part of the first gill arch behind the jaw fused to form a supporting strut. This attached the bottom jaw to the skull, increasing gape size
What are the reproductive strategies of Chondrichthyes
Oviparous = laying eggs
Ovoviviparous = eggs stay in uterus till hatching
Viviparous = placental with a live birth
What are the subclasses of Chondrichthyes
Holocephali (chimeras)
Elasmobranchii (sharks, rays and skates)
What are the two major groups of Osteichthyes
Actinopterygii (ray finned fishes)
Sarcopterygii (lobe finned fishes)
What are the key characteristics of amphibians
Legs
Cutaneous respiration
Lungs
Pulmonary arteries
Partially divided heart
What are the key characteristics of the life cycle of an amphibian
Tied to water
Lay eggs in water
Tadpole stage
Metamorphosis
Freshwater
How did lungs evolve in amphibians
Originated from an outgrowth from the gut and oesophagus. Amphibian lungs are like simple balloon structures that have their surface area increased by narrow septa. They are relatively inefficient
How do amphibians circulate air
Through buccal pumping
What are the orders of amphibians
Anura (frogs and toads)
Caudata (newts, salamanders and axolotls)
Apoda (caecilians)
What are the characteristics of an aminote egg
Has a series of extra embryonic membranes
Hard outer shell
What are the different membranes in an aminotic egg
Yolk sack: contains the yolk which provides the energy needed for development
Aminion: envelops the fluid sack with the developing embryo
Allantois: surface for gas exchange and waste storage
Chorion: carbon dioxide and oxygen transfer
How do eggs breathe?
The hard outer shell is porous
What are the 3 branches of aminotes and how are they distinguished
Early reptiles: anapsid skulls (no temporal fenestrae)
Mammals: synapsid skulls (one temporal fenestrae)
Birds and reptiles: diapsid skulls (two temporal fenestrae)
What are the key characteristics of reptiles
Impermeable skin
Aminote eggs
Metanephric kidneys
Efficient legs
More developed lungs
Efficient circulatory system
Powerful jaws
Internal fertilisation
What are the orders of reptiles
Reinchocephalia (tuataras)
Squamata (lizards and snakes)
Chelonia (turtles)
Crocodilia (crocodiles and alligators)
