Chapter 34-Vertebrate I Flashcards
What is Cranites?
Craniate include hagfish and all vertebrate.
What is the main characteristic of craniates?
- cranium: protective bony or cartilaginous housing enclosing the brain
- Neural crest: embryonic cells that will disperse throughout the embryo and lead to the formation of cranium, jaws, teeth, and peripheral nerves.
Hagfish
- Not true fish
- Jawless, finless, and no vertebral column
- Possess a skull and cartilaginous notochord
- primitive craniates resemble fossil found 530 mya
- Blind scavenger with keen sense of smell
- produces copious slime to deter predators.
chordate phylum
It has vertebrates subphylum:
- 60,000 species
- ranges in size from tiny fish to huge whales
- Occupy all earth’s biomes.
Vertebrates (subphylum)
Possess all chordate and craniates trait, plus,:
- vertebral column
- endoskeleton
- complex internal organs.
Vertebral column
Notochord develops into a bony or cartilaginous column of interlocking vertebrae.
Endoskeleton
Living internal skeleton of cartilage or bones. most have two or more pair of appendages (legs, fins,…)
Complex internal organs
Liver, kidney, endocrine glands, and a heart with two or more chambers.
Fishes
- 5 out of 11 existing vertebrae classes are fish
- about 30,000 species
- fishes are aquatic, gill-breathing ectotherm that possess fins and scaly skins.
Lampreys (class petromyzontida)
- primitive vertebrates that lacks jaws and appendages
- Notochord is primitive vertebral column composed of cartilage
- occur in marine and freshwater
- many are lampreys are parasitic
- circular mouth with rasp like teeth for sucking fluids from other fishes
- decimated important fish species in the great lakes.
Jawed fish
There are four classes of gnathostomes (jaw mouth)
Where does hinged jaw developed from?
Hinged jaw developed from pharyngeal arches and cartilaginous rods. (the original function of these were to flank the gill slits, and support the respiratory gill tissues)
Chondrichthyes class
It include:
- cartilaginous fish
- shark and rays
- skeleton composed of flexible cartilage.
Why cartilaginous fish have cartilage skeleton?
Most vertebral skeleton first begin as a cartilage model during development where cartilaginous fish retain that embryonic trait.
How many fins does shark possess?
Shark posses paired pectoral and pelvic fins, a powerful caudal fin and one or two dorsal fins.
What are the characteristic of the teeth and the skin of shark?
- Sharks possess a rough placoid scales on the skin which contain calcified tissue
- The teeth are modified scales. They continuously get replaced throughout the life.