BIOL211 Lecture Notes - Lecture 6: Spiny Dogfish, Nostril, Guanine
6 Dec 2014
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Document Summary
Can be divided into two groups: neoselachi neo = new; selach = shark. Have multiple gill openings on each side of the head. Includes extant sharks, skates & rays: holocephali holo = whole; cephalo = head. Condrichthyes do not have bone in their endoskeleton . Contain dentin, enameloid and traces of bone in their teeth & scales. All have unique scale in one form or another. The axial and appendicular skeleton does become mineralized on the superficial layer. Crystalline calcium forms tesserate or prismatic endoskeleton calcification. Cartilage allows for an increase in buoyancy still strong. Due to multiple layers & internal struts. Have a lipid filled liver contains oily lipids & hydrocarbons. Less dense than other body tissues can be large in size. Liver can allow the shark to be neutrally buoyant. Skates & bottom dwelling species have smaller livers . Extant species of the subclass elasmobranchii (neoselachii) consist of the. Galeomorph sharks include whale sharks, hammerheads, great whites.
