Jovimaeh S. Fuselero September 20, 2012BSMT – 2D Zoo 11

MUSCULAR SYSTEM OF INVERTEBRATES

Snails (Helix pomatia) They move by pedal locomotion,

movement by means of waves of activity in the muscular system that are applied to the substrate. Several waves cross the length of the foot simultaneously, each moving the same direction as the locomotion of the snail, but at a greater rate.

Pompeii worms (Alvinella pompejana) They move by the alternate movement of multiple limbs

(parapodia), the tips attach to the substrate, the body of the worm moves forward.

When they crawl slowly, the tips of the parapodia move backward relative to the body. Since the tips of the parapodia touch the substrate, this moves the body forward. In addition, a coordinate wave of activity in the parapodia passes forward from the tail to the head, with the left and right parapodia being exactly one half wavelength out of phase. This ensures that each parapodium executes its power stroke without interfering with the parapodium immediately posterior.

Starfishes or Sea Stars (Protoreaster linckii)

The water-vascular system enables them to move. They typically have five arms, with a water-vascular canal in each. Water comes into the system via the madreporite. It is then circulated from the stone canal to

the ring canal and into the radial canals.  Along each canal are reservoir ampullae and tube feet. Contraction of the muscles comprising the ampullae drives

water into the tube feet, whereas contraction of the tube feet moves water into the ampullae. Thus, the tube feet extend by hydraulic pressure and can perform simple, steplike motions.

Peacock Butterfly or European Peacock (Inachis io) They use direct or synchronous flight mechanism, in which

muscles acting on the bases of the wings contract to produce a downward thrust, and muscles attaching dorsally and ventrally on the exoskeleton contract to produce an upward thrust. The synchrony of direct flight mechanisms depends

on the never impulse to the flight muscles that must precede each wingbeat.

Leeches (Hirudo medicinalis)

Leeches are of three types -freshwater, terrestrial and marine. They exhibit looping movements. They

have anterior and posterior suckers and longitudinal muscles along the length of the body that provide alternating temporary points of attachment to move forward.