Transcript Chordata
Chordata Intro, Urochordata and Cephalochordata http://www.aboututila.com/PhotoGallery/DeepBlue/Photos/Bluebell-Tunicate-01.jpg Intro to Chordata http://myphlip.pearsoncmg.com/altcc/student/ab2page.cfm?vbcid=104 40&vid=19992 Characteristics of Chordata Deutorosomes, Bilaterally Symmetrical Four key characteristics: • Notochord - skeletal • Dorsal, hollow nerve cord - CNS • Pharyngeal slits or clefts – “gills” • Muscular, post-anal tail http://myphlip.pearsoncmg.com/altcc/student/ab2page.cfm?vbcid=10440&vid=19992 Tunicates Overview Tunicates are members of the subphylum Urochordata • • • • Nicknamed "Sea Squirts" Has body cavity that holds the atrium Bilaterally Symmetrical Nervous system degenerates after larval stage. Some cells detect light and gravity allowing it to settle on a substrate. Limited nervous system in adult stage. http://www.marinemedicaltreasures.com/images/tunicates.jpg Digestive, Excretory, and Circulatory Systems • • • • • Incurrent siphon sucks water Atrium filters food Water and waste excreted through excurrent siphon Food travels from esophagus to stomach Siphons also function as circulatory system http://myphlip.pearsoncmg.com/altcc/student/ab2page.cfm?vbcid=10440&vid=19992 Locomotion/Musculature • Uses tail muscles and notochord to swim as a larvae • Excurrent siphon can do jet propulsion Skeletal Type/Sensory Structures • Larval stage has notochord and dorsal, hollow nerve chord • In adult form the skeleton is lost and resorbed • Light and gravity sensing cells Reproduction • • • • Hermaphrodite = both male/female Settles on substrate Light and gravity cues Chordate characteristics disappear as adult Gas Exchange • Water is sucked in and pushed out through siphons • Diffusion Sample Example Organisms Class: Ascidiacea Order: Pleurogona Suborder: Stolidobranchia Family: Pyuridae Genus: Halocynthia Species: H. roretzi Sea Pineapple http://upload.wikimedia.org/wikipedia/commons/7/7e/Halocynthia_roret zi-Sea_pineapples_at_Tsukiji_Market-01.jpg http://www.biodiversity911.org/biodiversity_basics/why_important/images/red_sea_tunicates.jpg Lancelets/Cephalochordata • In the lavaral form lancelets develop a notochord, a dorsal, hollow nerve cord, numerous pharyngeal slits, and a post-anal tail. • Body Cavity is present. • Bilateral Symmetry • Feed on plankton. • Adult lancelets up to 5 cm long • Frequently swim to new locations • Lanclets- globally rare http://myphlip.pearsoncmg.com/altcc/student/ab2page.cfm?vbcid=10440&vid=19992 Nervous System • Lancelets develop a hollow nerve cord • Have slightly swollen tip on the anterior end of their dorsal nerve cord • However, no true brain http://myphlip.pearsoncmg.com/altcc/student/ab2page.cfm?vbcid=10440&vid=19992 Circulatory System • Water enters mouth and passes through the pharyngeal slits into the atrium • The atrium is a chamber that vents to the outside by way of the atriopore • No heart and blood cells Digestive System/Excretory System • Mucous net around pharyngeal slits remove small food particles from seawater • Ciliary pumping draws these particles into the mouth • Trapped food enters the intestine • Food finally leaves through anus Locomotion/Musculature • Swimming mechanism of fishes • Coordinated contraction of muscles • Serially arranged segmental muscles o Muscle segments develop from blocks of mesodermSomites • Undulatory (wavelike) movements Skeletal Type/Sensory Structures • As larvae develop a dorsal, hollow nerve cord and notochord • Somites found along each side of notochord • Tentacles by mouth act as sensory devices, and as a water filter • No eyes, or complex sensory structures Reproduction • • • • Sexual Reproduction Lanclets have separate sexes - Male & Female Eggs and Sperm released into water Fertilized eggs develop into larvae Gas Exchange • Diffusion across external body surface • Pharynx and Pharyngeal slits play a minor role in gas exchange http://www.uic.edu/classes/bios/bios100/labs/lance.jpg http://cfs15.tistory.com/image/32/tistory/2009/02/01/04/13/4984a2d26fa8e Lancelets are globally rare, but can reach large densities (5000/m2) in areas like Tampa Bay QUIZ TIME! 1) Which of following outline the notochord, and are prevalent in all chordate embryos? A. Atriums B. Somites C. Siphons D. Tunics QUIZ TIME! 1) Which of following outline the notochord, and are prevalent in all chordate embryos? A. Atriums B. Somites C. Siphons D. Tunics QUIZ TIME! 2) Mature tunicates are able to move by A. their muscles. B. clinging to other animals as they pass by. C. teleportaion. D. jet propulsion. QUIZ TIME! 2) Mature tunicates are able to move by A. their muscles. B. clinging to other animals as they pass by. C. teleportaion. D. jet propulsion QUIZ TIME! 3. Chordates are A. bilaterally symmetrical. B. radially symmetrical. C. not symmetrical at all. D. aesthetically symmetrical. QUIZ TIME! 3. Chordates are A. bilaterally symmetrical. B. radially symmetrical. C. not symmetrical at all. D. aesthetically symmetrical. QUIZ TIME! 4. Tunicates _____ and Lancelets _____. A. are sexual; are asexual B. are asexual; are sexual C. have separate sexes; are hermaphrodites D. are hermaphrodites; have separate sexes QUIZ TIME! 4. Tunicates _____ and Lancelets _____. A. are sexual; are asexual B. are asexual; are sexual C. have separate sexes; are hermaphrodites D. are hermaphrodites; have separate sexes