labpracticle_review - Phylum: CHORDATA 5 Diagnostic...

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Phylum: CHORDATA 5 Diagnostic Characters Hollow dorsal nerve cord Notochord- dorsal flexible structure used for support Clefts or gill slits through the pharyngeal wall Post-anal tail Endostyle from which the thyroid gland is derived Subphylum Vertebrata Includes ~45,000, most fishes Characters (in addition to chordate characters) o Hard endoskeleton of cartilage or bone made with calcium phosphate (including vertebral column and brain case). Supports and protects body in all groups except hagfishes and lampreys (who have small endoskeleton made of cartilage) (hagfish do not have vertebral column at all) o Hinged jaw Except in hagfishes and lampreys For opening mouths wide and have tremendous crushing ability o Ventral heart of 2-4 chambers o Paired kidneys for excretion KEY 1. Jaws absent go to 2 Jaws present go to 3 2. 7 pairs of gill openings, rasping tongue Class Cephalaspidomorphi (lampreys) 1-14 pairs of gill openings, rasping tongue Class Myxini (hagfishes) 3. Smooth skin, 4 digits on front limbs Class Amphibia Rough skin, scales/fur/feathers present go to 4 4. Aquatic animals, swimming fins usually present go to 5 Usually terrestrial animals, swimming fins usually absent go to 6 5. Skeleton made of cartilage Class Chondrichthyes (sharks, skates, rays) Skeleton made of bone Class Osteichthyes (bony fishes) 6. Scales and/or feathers present, occipital condyle Class Reptilia (birds and reptiles) Hair present, mammary glands, 2 occipital condyles Class Mammalia (mammals) Occipital Condyles Vertebrate head attached to spinal column at base of skull with occipital condyles o Reptiles have 1 o Mammals have 2 (cannot rotate head as much) Vertebrate Skin Dermal scales- both layers ripple around and over scale Epidermal scales- dermis flat Fish scales: dermal Bird feathers: epidermal Reptile scales: epidermal Mammal hair: epidermal
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Thus, fish scales homoplasious to reptiles scales
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This note was uploaded on 04/07/2008 for the course BIS 001B taught by Professor Kimsey&rosenheim during the Winter '08 term at UC Davis.

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labpracticle_review - Phylum: CHORDATA 5 Diagnostic...

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