BIOL 111 Lecture Notes - Lecture 13: External Fertilization, Lipid Bilayer, Convergent Evolution
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BIOL 111 Full Course Notes
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Document Summary
Cephalized, nerve cords with nerve ring or brain. Extremely abundant and diverse in marine, freshwater and terrestrial environments. Rasping organ that reduces any prey to small fragments passed to the pharynx: foot. Attaches the animal firmly to the substrate (during locomotion or at rest: during locomotion: weak adhesive force needed, at rest: requires strong adhesive force. Moves the animal by waves of muscular contraction. Gel consists of polymers: mantle and shell. Calcium is very abundant in their environment allows to make the shell. 3 layers of shell: outermost: periostracum tough, organic, made of chitin. This is where growth occurs: middle: prismatic layer calcium carbonate as calcite. Innermost: nacreous layer calcium carbonate as aragonite. Elongated cone wound into a spiral around a central axis, the columella. An elongate uncoiled shell would be impossible to carry because of its high centre of gravity: nervous system. Sophisticated nervous system consists of ganglia and nerve cords.
