Nageoire Caudale, le moteur !

It’s the main propulsion mean. The fin base is thick and become thinner as it reaches the side (and quicker than the axis). As with the dorsal the fluke has neither bones or cartilage but nearly exclusively muscles and fibrous tissues. From the base of the fin to the ventral area, muscles are mainly verticals, which is perpendicular to the head to fluke axis. These muscles are very strong and powerful (multi tendons). A precise and powerful movement is created vertically by the caudal when the muscles contract. The move generates a wave that will propel the orca forward. The move is horizontal (the animal goes forward…). There is a slight horizontal motion of the caudal made by some small lateral moves of the spine.
THE CAUDAL FIN is therefore the MAIN LOCOMOTION organ.

The paddle has a dual function, by being hard it optimise the powerful effect (therefore speed and acceleration). By curving very slightly the edges, it emphasises this effect.

The paddle is made of 3 layers

  • A lard layer, fibrous.
  • A very fibrous layer going from the terminal vertebras to the lateral edges of the fin.
    • A fibrous layer going from the side to the back of the fin.

     

     

     


     Nageoire PectoraleNageoire Pectorale

    Very powerful muscles action the anterior members also called pectoral fins. They must be able to be used even when the killer whale is moving at high speed. The padlle doesn’t show any member or fingers despite a very well developed hand hidden under the thick skin. The fin does not bend, it remains straight. It can be up to as high as a 1/5 of the total length of the body in some individual.
    SEE BONE SYSTEM

    PECTORALS HAVE SEVERAL ROLES:
    RUDDER: While moving, the orientation of the palette allows very precise trajectory modification (remember that the fluke has only a vertical movement to generate an horizontal and forward motion).

    BREAKS: Positioned the most perpendicular to the motion axis, palettes became very efficient and precise breaks.

    THERMOREGULATOR: Because of their lack of thickness compared to the rest of the body (except fins), palettes act as temperature sensors. They are going to regulate the body temperature by cooling the blood circulating in them. It’s the thermal changes effect.
    SEE THREMOREGULATION

     


     

    FemaleDorsale de la Femelle, falciforme Dorsale du mâle, triangulaire  Male

    This fin is situated on the back of the animal, at about mid-length. With the females it is falciform and is about a metre high. With the males, it is triangular shaped and measure between 1.7 to 2 metres (killer whales were called ORCA GLADIATOR because the shape of this fin remind the two-edged sword).

    THIS FIN HAS 2 ROLES:

    THERMOREGULATOR: It works the same way than the pectorals but here the regulation can be done according to the outside temperature as well.
    SEE THERMOREGULATION.

    STABILISER: It helps maintaining the heading and avoids rolling. It acts like a keel on a boat

    Like the fluke, the dorsal does not have any bones or cartilage. It is made of a skin layer (same thickness as the rest of the body), of tissue and of a thick fibrous layer. Inside the fins is made of conjunctive tissues, which fibres go from one side of the fin to the other (perpendicular to the body axis).