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Zoology
WCHS Zoology Chapter 17 Classifcation of Hemichordata and Chordata
Word | Definition |
---|---|
phylum Hemichordate | widely distributed in shallow, marine, tropical waters and deep, cold waters; soft bodied and wormlike; epidermal nervous system; most with pharyngeal slits |
Class Enteropneusta | shallow-water, wormlike animal; inhabit burrows on sandy shorelines; body divided into three regions; proboscis, collar and trunk, Acorn worms, about 75 species |
Class Pterobranchia | with or without pharyngeal slits; two or more arms; often colonial, living in an externally secreted encasement, about 20 species |
Class Plantosphaeroidea | Spherical body with ciliary bands covering the surface; U-shaped degestive tract; coelom poorly developed; planktonic, only one species is known to exist |
Phylum Chordata | Occupy a wide variety of marine, freshwater, and terrestrial habitats, a notochord, pharyngeal slits, a dorsal tubular nerve cord, and a postanal tail are all present at some time in chordate life histories, about 45,000 species |
subphylum Urochordata | Notochord, nerve cord, and postanal tail present only in free-swimming larvae; adults sessile, or occasionally planktonic, and encolsed in a tunic that contains some cellulose; marine, Sea squirts or tunicates |
Class Ascidiacea | all sessile as adults; solitary or colonial; colony members interconnected by stolons, sea squirts |
Class Appendicularia | (larvacea) Planktonic; adults retain tail and notochord; lack a cellulose tunic; epithelium secretes a gelatinous covering of the body; appenicularians (Fritillaria) |
Larvacea | The class of urochordates whose members are planktonic and whose adults retain a tail and notchchord with a gelatinous covering of the body |
Class Sorberacea | ascidian-like urochordates possessing dorsal nerve cords as adults; deep water, benthic; carnivorous, Octacnemus |
Class Thaliacea | Plnaktonic; adults are tailess and barrel shaped; oral and atrial openings are at opposite ends of the tunicate; muscular contractions of the body wall produce water currents; Salps (Salpa, Thetys) |
Subphylum Cephalochordate | body laterally compressed and transparent; fishlike; all four chordate characteristics persist throughout life. Amphoxus (Branchiostoma) about 45 species |
Craniata | skull surrounds the brain, olfactory organs, eyes, and inner ear; unique embryonic tissue, neutral crest, contributes to a variety of adult structures including sensory nerve cells, and some skeletal and other connective tissue structures |
Subphylum Hypertreti | Fishlike; skull consisting of cartilaginous bars; jawless; no paired appendages; mouth with four pairs of tentacles; olfactory sacs open to mouth cavity; 5 to 15 pairs of pharyngeal slits; ventrolateral slime glands: Hagfishes |
Subphylum Vertebrata | Notochord, nerve cord, postanal tail, and pharyngeal slits present at least in embryonic stages; vertebrae surround nerve cord and serve as primary axial support |
Class Cephalaspidomorphi | Fishlike; jawless; no paired appendages; cartilaginous skeleton; sucking mouth with teeth and rasping tongue; Lampreys |
Class Chondrichthyes | Fishlike; jawed; paired appendages and cartlaginous skeleton; no swim bladder; Skates, rays, sharks. |
Class Osteichthyes | Bony skeleton; swim bladder and operculum present; bony fishes. |
Class Amphibia | skin with mucoid sectetions; possess lungs and/or gills; moist skin serves as respiratory organ; aquatic develpmental stages usually followed by metamorphosis to an adult; Frogs, toads, slamanders |
Class Reptilia | Dry skin with epidermal scales; amniotic eggs; terrestial embryonic develpment; Snakes, lizards, alligators |
Class Aves | Scales modified into feathers for flight; efficiently regulate body temerature (endothermic) amniotic eggs, Birds |
Class Mammalia | Bodies at least partially covered by hair; endotheric; young nursed from mammary glands; amniotic eggs; Mammals |