Topic 27: Clade Vertebrata Flashcards
Clade Vertabrata
Chordates with back bone that protects a complex nervous system.
Vertebrate Traits
Vertebral column, braincase (cranium), more Hox genes, Neural crest cells, fins, complex circulatory system
Neural Crest Cells
Contributes to teeth, neurons.
Fins
Membrane extensions supported by cartilage and stiffened by fin rays.
Circulatory System
Closed with heart w/ 2 chambers, transport 02 w/ hemoglobin
Basal Vertebrates
Lack jaws - Clade Cyclostomes (Hagfish, Lamprey)
Hagfishes
Jawless, with cartilaginous cranium.
Lampreys
Have cartilage skeleton and no jaw or paired limbs. Often parasites to fish.
Conodonts
Earliest vertebrate in fossil record, cartilaginous cranium and vertebral column, with a mineralized skeletal elements.
Clade Gnathostomes
Vertebrates that have opposing jaws. (psss its just sharks)
Gnathostomes Traits
Jaws, Mineralized skeleton, lateral appendages, double Hox genes, Enlarged forebrain (smell), Lateral line system
Lateral Line System
Detect vibration in the water
Origin of Jaws and Mineralization
evolved simultaneously, natural selection favoured mineralization in jaw region.
Endoskeleton
Derived from preformed cartilage
Dermal Skeletal Structures
Derived from intramembranous (within skin layer) ossification
Three Lineages of Extant Gnathostomes
Chondrichthyans, Ray-finned fish, lobe-fish.
Chondrichthyans
Sharks, rays, have cartilaginous skeletons w/ bony teeth and scales, lost mineralization.
Sharks
Rely on ram ventilation: swim with mouths open, allowing water to pass over their gills, facilitating oxygen. Continually move to maintain buoyancy, cloaca, copulation and internal embryo development (various ways).
Buccal Pump
Force water over gills by opening and closing mouth
Oviparous
Laying egg outside in an egg case.
Ovoviviparous
Develop in uterus w/ no blood connection
Viviparous
Develop in uterus with blood connection.
