BIO325H5 Lecture Notes - Lecture 2: Shoulder Girdle, Collagen, Muscle Contraction
Document Summary
Fins are better than paddles: various paddle strokes --sweep, draw, feather, etc propel and manoeuver a canoe. But a fish fin does them all better because of its fin flexibility,achieved by individually controlled lepidotrichiamoving in a collagenous membrane. Fish fins control surfaces: hydrofoils for lift, rudders, brakes. Single-oar sculling: propelling a watercraft by moving a single, stern-mounted oar from side to side, while changing the angle of the blade so as to generate forward thrust on both strokes (think venice and gondolas). Canoeists scull or feather" in this way and fish do the same, but fish fins are much more effective than a paddle because of their changing curvature. This has to do with independently acting leptotrichia(fin rays) that brace intervening (collagen) membranes. In the case of pectoral fins the fin muscles promotors & remotorsor (same thing) adductors and abductors originate on the pectoral girdle and insert on the hemitrichunsegmented base via ligaments.
