Vertebrates 1

Question 1

Chordates

Answer 1

Animals that, at least one stage had;
* Notochord - stiff cartelingous rods that extend inside along the body
* Dorsal, hollow nerve cord - main trunk of central nervous system
* Pharyngeal slits - Pharynx part of throat, maybe modified into gills
* Post anal tail

Question 2

Non-vertebrate chordates

Answer 2

• Small marine animals
• Tunicates: most adults sessiles and lack many chordate features, have pharyngeal slits for filter feeding
• Lancelets: Larvae form has many chordate features, adults only have pharyngeal slits. Adultsfishlike, mistly burrowing and sedentary

Question 3

Vertebrate Chordates

Answer 3

• Vertebral coloumn - notochord modified into cartilliaginous or bony vertebrate, sperated by mobile joints (SPINE)
• Cranium-cartilaginous or bony braincase
• Spiny cord - modified dorsal nerve cord
• Neural crest - group of mobile embryonic cells that give rise to diverese cell types
• Large 3 part brain
• Complex organs

Question 4

Evolutionary origins

Answer 4

• most animal phyla, including cordata, appareared 540-480MYA
• Few non-vertebrate fossiles
• 65,000 descreibed species
• Highest density in tropics

Question 5

Jawless fish (Agnatha)

Answer 5

• Lack jaws and paired fins
• Elongated body, scaleless and slimy
• Hagfish: No vertebrate collumn, marine scavenger of sea floor
• Lampreys: Rudimentary vertebrate, parasite to many fish

Question 6

Cartilaginous Fish (Chondrichthyes)

Answer 6

• Cartilaginous skeletons and paired fins
• Sharks, skates and rays: multiple fin openings
• Chimaearas: single gill opening

Question 7

Bony fish (Osteichthyes)

Answer 7

• bony skeltons and paired fins, swim bladders
• Rayfinned: fins are webs supported by spines. 90% of all fish
• Lobefinned: fleshy lobed fins attaches to a single bone, ancestral to tetrapods

Question 8

Amphibians

Answer 8

• Tetrapods with moist skin
• Many with aquatic larve
• Canivorous adults
• Frogs and toads (Anura): short body, large head and hindlegs
• Salamanders (Urodela): Terrestrail adults
• Coelcillians (Apoda): Legless, poorly known, reduced sight

Question 9

Reptiles

Answer 9

• Tetrapods with scaly skin
• Amiotes - no aqautic stage
• Groups gave rise to birds and mammals
• Turtles (Testudines): bony or cartilignous shells derived from ribs
• Lizards and snakes (Squamata): Horny scaled skin, movable quadrates
• Crocodillians: large and lizard like, aquatic lifestyle and flatterened long snouts