Jackson Estuarine Laboratory

Limulus gill cleaning behavior


  1. The gill cleaning movements ofLimulus occur in definite periods (bouts). The sequence of movements in a bout, and the movements themselves, are highly stereotyped.
  2. In a bout of gill cleaning the paired gill plates are adducted across the midline so that opposite gill plates can interact. The interaction consists of rhythmic flicking of the inner lobe of a gill plate between the book gill lamellae of the contralateral gill.
  3. Each bout of cleaning lasts for approximately one minute and can be divided into four basic phases: pairing, crossing over, lateral cleaning, and medial cleaning (Fig. 2).
  4. There are two distinct pairing arrangements of the gill plates during cleaning. During left leading (LL) cleaning all the gill plates are paired with an adjacent gill plate, except L1 and R5. During right leading (RL) cleaning, which is the mirror image of LL cleaning, all the gills are paired except for R1 and L5 (Fig. 3).
  5. Cleaning bouts are further organized into long-term patterns which last for hours (Fig. 4).
  6. There are four major muscle groups involved in gill cleaning. Muscles 48/115 adduct the gill plate across the midline; muscles 113/114 flick the inner lobe, and muscles 20 (remotor) and 22 (promotor) control the anterior-posterior position of the gill plate during cleaning. The patterns of activity of these muscles are reliably different during RL and LL cleaning (Fig. 5).
  7. Each abdominal ganglion controls the movements of a pair of gill plates. During a bout of cleaning one member of the pair is being cleaned (subprogram A) and the other is not being cleaned (subprogram B). It is suggested that there are higher-order interganglionic neurons which control the expression of either the RL or LL patterns of cleaning. This is accomplished by dictating which gill plate of a pair uses subprogram A and which subprogram B, for all five ganglia.
  8. It is concluded that a gill cleaning bout constitutes a moderately complex fixed action pattern, meeting the criteria of stereotypy within and between animals, intricacy of appendage movements, involvement of more than one effector system, and tendency to occur in its entirety in the absence of apparent stimuli (vacuum activity).


Jackson Estuarine Laboratory, Biological Sciences

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Journal of comparative physiology



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© Springer-Verlag 1980