Swimming in the sea anemone Stomphia coccinea triggered by a slow conduction system

Nature ◽  
1976 ◽  
Vol 262 (5570) ◽  
pp. 708-709 ◽  
Author(s):  
I. D. LAWN
Keyword(s):  
Conduction System ◽  
Sea Anemone ◽  
Slow Conduction

Control of Preparatory Feeding Behaviour in the Sea Anemone Tealia Felina

1970 ◽  
Vol 53 (1) ◽  
pp. 211-220
Author(s):  
I. D. McFARLANE
Keyword(s):  
Electrical Stimulation ◽  
Feeding Behaviour ◽  
Mouth Opening ◽  
Conduction System ◽  
Sea Anemone ◽  
Feeding Response ◽  
Slow Conduction ◽  
Oral Disk ◽  
Stimulation Of

1. Dissolved food substances elicit preparatory feeding behaviour in the sea anemone Tealia felina. This behaviour takes the form of expansion of the oral disk and lowering of the margin of the disk. Food may also cause mouth opening and pharynx protrusion. This pre-feeding response may increase the chance of food capture. 2. The expansion and lowering of the oral disk can also be elicited by electrical stimulation of a slow conduction system, the SS1, thought to be located in the ectoderm. 3. SS1 activity is seen when the anemone is exposed to dissolved food substances. 4. It is concluded that preparatory feeding behaviour in Tealia is mediated in part by the SS1.

Control of shell settling in the swimming sea anemone Stomphia coccinea

1976 ◽  
Vol 64 (2) ◽  
pp. 419-429
Author(s):  
I. D. Lawn
Keyword(s):  
Electrical Stimulation ◽  
Electrical Activity ◽  
Complete Response ◽  
Conduction System ◽  
Sea Anemone ◽  
Interpulse Interval ◽  
Slow Conduction ◽  
Behavioural Sequence ◽  
Pedal Disc ◽  
Stimulation Of

1. Electrical activity has been recorded from Stomphia coccinea during the behavioural sequence in which the detached anemone settles on to a Modiolus shell. 2. When a responsive tentacle contacts the shell, a short, complex burst of pulses is elicited. These remain confined to the region of contact. The endodermal slow-conduction system (SS2) then begins to fire repetitively (a typical example is 16 SS2 pulses at a mean interpulse interval of 5 s) until the pedal disc begins to inflate. Shell-tentacle contact is essential for stimulation of SS2 activity. 3. The complete response, apart from local bending of the column, may be reproduced by electrical stimulation of the SS2 alone. As few as 10 stimuli at frequencies between 1 shock/s and 1 shock/10 s are required to elicit the response.

Two Slow Conduction Systems in the Sea Anemone Calliactis Parasitica

1969 ◽  
Vol 51 (2) ◽  
pp. 377-385 ◽  
Author(s):  
I. D. MCFARLANE
Keyword(s):  
Electrical Activity ◽  
Conduction Velocity ◽  
Conduction System ◽  
Repetitive Stimulation ◽  
Sea Anemone ◽  
Response Delay ◽  
The Third ◽  
Slow Conduction ◽  
Calliactis Parasitica ◽  
Oral Disk

1. Suction electrodes record electrical activity associated with three conduction systems in the sea anemone Calliactis parasitica. The two slow systems (SS1 and SS2) are previously undescribed. The third system is the through-conduction system. 2. Evidence is given that the SS1 and SS2 are located in the ectoderm and endoderm respectively. The conductile elements have not been identified. 3. The conduction velocity of the SS1 is 4.4-14.6 cm./sec. at 11° C. and is highest in the oral disk. The SS2 velocity is 3.0-5.3 cm./sec. 4. Both slow systems show a marked increase in response delay on repetitive stimulation and fail at stimulation frequencies higher than one shock/3 sec.

A Transmesogloeal Conduction System in the Swimming Sea Anemone Stomphia

1980 ◽  
Vol 87 (1) ◽  
pp. 45-52
Author(s):  
I.D. LAWN
Keyword(s):  
Electrical Activity ◽  
Conduction System ◽  
Nerve Cells ◽  
Sea Anemone

1. A conduction system in Stomphia transfers information across the mesogloea from ectodermal receptors to endodermal effectors. 2. In the column, this transmesogloeal system has numerous and widespread connexions. 3. It is suggested that the connexions may be processes from multipolar nerve cells located in the endoderm. 4. Certain aspects of behaviour are controlled by this conduction system which provides yet another pathway to co-ordinate electrical activity.

scholarly journals Co-Ordination of Pedal-Disk Detachment in the Sea Anemone Calliactis Parasitica

1969 ◽  
Vol 51 (2) ◽  
pp. 387-396
Author(s):  
I. D. MCFARLANE
Keyword(s):  
Electrical Stimulation ◽  
Electrical Activity ◽  
Mechanical Stimulation ◽  
Average Frequency ◽  
Conduction System ◽  
Identical Stimulus ◽  
Slow Conduction ◽  
Calliactis Parasitica ◽  
Behavioural Sequence ◽  
Stimulation Of

1. Electrical activity has been recorded from the sphincter region of Calliactis parasitica during the behavioural sequence in which the anemone detaches from the substrate and attaches to a Buccinum shell. The ectodermal slow-conduction system (SS1) fires repetitively, the majority of observed pulses occurring in the period prior to detachment (a typical example is 25 SS1pulses at an average frequency of 1 pulse/7 sec.). Shell-tentacle contact is essential for stimulation of SS1activity. 2. Mechanical stimulation of the column excites the SS1, and 30 stimuli at a frequency of about one shock/5 sec. give pedal disk detachment. 3. Electrical stimulation of the ectoderm excites the SS1and about 30 stimuli at frequencies between one shock/3 sec. and one shock/9 sec. produce detachment. Detachment and the SS1 have an identical stimulus threshold. It is concluded that detachment is co-ordinated by the SS1.

Control of the Pacemaker System of the Nervenet in the Sea Anemone Calliactis Parasitica

1974 ◽  
Vol 61 (1) ◽  
pp. 129-143
Author(s):  
I. D. MCFARLANE
Keyword(s):  
Sensory Feedback ◽  
Pulse Frequency ◽  
Pulse Number ◽  
Pulse Action ◽  
Conduction System ◽  
The Body ◽  
Optimum Frequency ◽  
Nerve Net ◽  
Slow Conduction ◽  
Calliactis Parasitica

1. The rhythm of spontaneous nerve-net pulses is reset by intercalated evoked nerve-net pulses. 2. The origin of spontaneous nerve-net pulses can shift during a burst. There seem to be many potential pacemakers, widely distributed throughout the body, but apparently absent from the tentacles. 3. If a spontaneous or evoked pulse in the endodermal slow conduction system (SS 2) occurs during a burst, the nerve-net pulse intervals are increased during a 15-30 sec period following the SS 2 pulse. Additional SS 2 pulses cause a further increase in pulse intervals. 4. Nerve-net bursts are followed by a sequence of muscular contractions. The size of the contraction shown by any muscle group depends on nerve-net pulse number and frequency, the optimum frequency being different for different muscles. It is suggested that the SS 2 pulse action on nerve-net pulse frequency can significantly alter the behavioural output of nerve-net bursts. The SS 2 activity may represent sensory feedback on to the nervous pacemakers.

The role of a ‘local electrical conduction system’ during feeding in the Devonshire cup coral Caryophyllia smithii Stokes and Broderip

1984 ◽  
Vol 220 (1221) ◽  
pp. 489-500 ◽  
Keyword(s):  
Electrical Conduction ◽  
Feeding Behaviour ◽  
Complete Sequence ◽  
Conduction System ◽  
Oral Disc ◽  
Nerve Net ◽  
Slow Conduction ◽  
Spread Of Excitation ◽  
Radial Spread ◽  
Slow System

The electrical conduction systems underlying the control of feeding behaviour are described for the solitary cup coral Caryophyllia smithii . A nerve net and a slow conduction system were found to conduct non-decrementally to all parts of the animal and to control symmetrical parts of the feeding behaviour such as polyp expansion. The slow system was activated by receptors on the tentacles and oral disc. Of particular interest was the presence of a ‘local conduction system’ in the tentacles and oral disc. This system was shown to be important in the control of local, asymmetrical parts of the feeding behaviour such as the movements of single tentacles. The local conduction system consisted of radially conducting units each of which consisted of a single tentacle and its associated sector of oral disc. This allowed the radial spread of excitation (at less than 2 cm s -1 ) from tentacle to mouth or mouth to tentacle but did not allow excitation to spread around the oral disc. The threshold for excitation of the local conduction system was above that of the nerve net or slow conduction system. The cellular basis for local conduction is unknown but may involve the oral disc radial muscles and the tentacle longitudinal muscles. By appropriate electrical stimulation of the nerve net, slow system and local conduction system, a complete sequence of feeding behaviour could be evoked. This closely resembled the behaviour shown during normal feeding and included polyp expansion, local pharynx movements and local tentacle bending. It is concluded that ‘local conduction’ is an important element to include in models purporting to explain the control of anthozoan behaviour, particularly that in which local movements are important.

Excitatory Actions of Antho-RFamide, An Anthozoan Neuropeptide, on Muscles and Conducting Systems in the Sea Anemone Calliactis Parasitica

1987 ◽  
Vol 133 (1) ◽  
pp. 157-168 ◽  
Author(s):  
I. D. McFARLANE ◽  
D. GRAFF ◽  
C. J.P. GRIMMELIKHUIJZEN
Keyword(s):  
Electrical Activity ◽  
Slow Muscle ◽  
Conduction System ◽  
Sea Anemone ◽  
Sea Anemones ◽  
Nerve Net ◽  
Direct Excitation ◽  
Calliactis Parasitica ◽  
Muscle Groups ◽  
Fast Muscles

In the sea anemone Calliactis parasitica endodermal application of the anthozoan neuropeptide Antho-RFamide (<Glu-Gly-Arg-Phe-amide), at a concentration of 10−6 or 10−7moll−1, caused a long-lasting increase in tone, contraction frequency and contraction amplitude in several slow muscle groups but had no effect on contractions in fast muscles. The effects were investigated further in isolated muscle preparations. Ectodermal application to whole animals had no effect on muscle contractions. Both ectodermal and endodermal application, at 10−7moll−1, raised electrical activity in an ectodermal conduction system, the SSI, but had no effect on an endodermal conduction system, the SS2. Electrical activity in the SS2 was increased by application at 10−6moll−1 to the endoderm but not to the ectoderm. The peptide had no effect on the through-conducting nerve net. It is concluded that contractions evoked by Antho-RFamide may be partly due to neuronal activity, but probably also involve direct excitation of the muscles. The diverse excitatory actions of Antho-RFamide suggest that it may be a neurotransmitter or neuromodulator in sea anemones.

scholarly journals Nerve Nets and Conducting Systems in Sea Anemones: Two Pathways Excite Tentacle Contractions in Calliactis Parasitica

1984 ◽  
Vol 108 (1) ◽  
pp. 137-149
Author(s):  
IAN D. MCFARLANE
Keyword(s):  
Electrical Activity ◽  
Conduction System ◽  
Sea Anemones ◽  
Single Shock ◽  
Nerve Net ◽  
Slow Conduction ◽  
Calliactis Parasitica ◽  
Slight Movement ◽  
Pulse Stimulation ◽  
Stimulation Of

1. Single shocks to the column sometimes evoke tentacle contractions, ranging from slight movement of a few scattered tentacles to rapid bending or shortening of all the tentacles. Some individuals are more responsive than others. Complex bursts of electrical activity follow single shocks, but only in tentacles that contract. 2. These single shocks excite pulses in two conducting systems - the through-conducting nerve net (TCNN) and the ectodermal slow conduction system (SSI). When a single shock evokes contractions and bursts of electrical activity, these usually follow the SSI pulse, rarely the TCNN pulse. Stimulation of the SSI alone causes tentacle contraction in responsive anemones. 3. Fast tentacle contractions always follow the second of two closelyspaced TCNN pulses: the TCNN shows facilitation (Pantin, 1935a). An SSI pulse, however, does not facilitate subsequent pulses in either the SSI or TCNN. 4. There are two pathways for activation of tentacle contractions. The TCNN pathway is mechano-sensitive and normally requires facilitation. The SSI pathway is mechano- and chemosensitive, only requires a single SSI pulse to evoke contraction, but is very labile. It is proposed that the TCNN and the SSI do not excite the ectodermal muscles directly, but via a multipolar nerve net.

scholarly journals Reversal of the Direction of Mucus-Flow on the Ciliated Pharynx of a Sea Anemone

1984 ◽  
Vol 108 (1) ◽  
pp. 151-161
Author(s):  
M. C. HOLLEY ◽  
G.A. B. SHELTON
Keyword(s):  
Electrical Activity ◽  
Direct Observation ◽  
Electrical Conduction ◽  
Conduction System ◽  
Sea Anemone ◽  
Power Stroke ◽  
Ciliary Beating ◽  
Calliactis Parasitica

1. The ciliated pharynx of the sea anemone Calliactis parasitica (Couch) acts as an independent selective barrier for the admission of material to the coelenteron. 2. Direct observation shows that reversal of the direction of the mucus-flow is effected by a reversal of the direction of the ciliary power-stroke. 3. Reversal of the power-stroke can only be stimulated by food juices applied directly to the pharynx and it is not propagated to unstimulated areas. 4. Reversal of the power-stroke occurs in the absence of all recordable electrical activity. 5. This is one of the few examples among the Metazoa where it has been shown that a modification of the ciliary beating pattern is unlikely to be controlled by an electrical conduction system.

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