phylum+echinodermata,+chordate+characteristics

ZOOLOGY NOTES—ECHINODERMS AND CHORDATES PHYLUM ECHINODERMATA CLASS ASTEROIDEA—SEA STARS (STARFISH) CLASS OPHIUROIDEA—BRITTLE STARS CLASS ECHINOIDEA—SEA URCHINS AND SAND DOLLARS CLASS HOLOTHUROIDEA—SEA CUCUMBERS CLASS CRINOIDEA—SEA LILIES AND FEATHER STARS PHYLUM CHORDATA GENERAL CHARACTERISTICS ü BILATERAL SYMMETRY ü THREE GERM LAYERS—ENDODERM, MESODERM, ECTODERM ü WELL-DEVELOPED COELOM ü UNSEGMENTED TRUNK ü CLOSED CIRCULATORY SYSTEM ü COMPLETE DIGESTIVE SYSTEM ü CARTILAGINOUS OR BONY ENDOSKELETON PRESENT IN MOST SPECIAL CHARACTERISTICS 1) NOTOCHORD Ø  A FLEXIBLE, ROD-LIKE STRUCTURE THAT EXTENDS THE LENGTH OF THE BODY Ø  THE NOTOCHORD IS REPLACED BY THE VERTEBRAL COLUMN IN MOST VERTEBRATES, ALTHOUGH SOME PORTIONS REMAIN BETWEEN OR WITHIN THE VERTEBRAE   2)  DORSAL TUBULAR NERVE CORD o SPINAL CORD o THE ANTERIOR END ENLARGES TO FORM THE BRAIN o BOTH ARE PROTECTED BY THE VERTEBRAL COLUMN AND THE CRANIUM 3) PHARYNGEAL POUCHES AND GILL SLITS v  AQUATIC CHORDATES HAVE GILLS WITH WHICH THEY BREATHE v  IN TETRAPOD VERTEBRATES (FOUR-LEGGED ANIMALS), THESE POUCHES EVENTUALLY FORM THE TONSILS, MIDDLE EAR CAVITY, EUSTACHIAN TUBE, AND PARATHYROID GLANDS   4)  POSTANAL TAIL  MAINLY USEFUL FOR PROPULSION IN WATER  MOST MAMMALS HAVE A WAGGABLE TAIL <span style="font-family: Symbol; mso-bidi-font-family: Symbol; mso-fareast-font-family: Symbol; msobidifontfamily: Symbol; msofareastfontfamily: Symbol; msolist: Ignore;"> THE TAIL OF HUMANS IS SEEN AS A SERIES OF SMALL VERTEBRAE AT THE END OF THE SPINAL COLUMN (COCCYX) SUBPHYLUM UROCHORDATA * ALSO CALLED TUNICATA, OR TUNICATES * MARINE * MOST ARE SESSILE (ATTACHED TO A SUBSTRATE) AS ADULTS * USUALLY SURROUNDED BY A TOUGH TUNIC COMPOSED OF CELLULOSE * THE MOST WELL-KNOWN MEMBERS ARE CALLED SEA SQUIRTS SUBPHYLUM CEPHALOCHORDATA +LANCELETS, OFTEN CALLED AMPHIOXUS +CLEARLY DEMONSTRATE ALL FOUR BASIC CHARACTERISTICS OF CHORDATES SUBPHYLUM VERTEBRATA # ALSO CALLED CRANIATA # LIVING ENDOSKELETON, WHICH IS MUCH BETTER THAN THE NON-LIVING EXOSKELETON OF MANY INVERTEBRATES
 * RADIAL, PENTAMEROUS SYMMETRY (FIVE OR MORE ARMS)
 * NO HEAD OR BRAIN
 * ENDOSKELETON STRENGTHENED WITH CALCIUM
 * WATER-VASCULAR SYSTEM
 * LOCOMOTION BY TUBE FEET
 * COMPLETE DIGESTIVE SYSTEM
 * EXTENSIVE COELOM
 * MUCH REDUCED CIRCULATORY SYSTEM
 * NO EXCRETORY ORGANS
 * DIOECIOUS
 * LARVAL STAGES HAVE BILATERAL SYMMETRY
 * ALL MARINE
 * 1) THE STRONG ENDOSKELETON ALLOWS FOR SUPPORT OF THE LARGE BODY SIZE OF MANY LAND VERTEBRATES
 * 2) HIGHLY ADVANCED NERVOUS SYSTEM
 * 3) PAIRED APPENDAGES IN MOST
 * 4) THE AMMOCOETE LARVA OF LAMPREYS IS USED AS A MODEL FOR THE VERTEBRATE BODY PLAN
 * 5) ALLVERTEBRATES WITH JAWS ARE CALLED GNATHOSTOMES
 * 6) JAWLESS VERTEBRATES ARE AGNATHANS