Lipid biosynthesis in warm- and cold-acclimatized sea anemones, Metridium senile (L.)

1980 ◽  
Vol 48 (2) ◽  
pp. 113-121 ◽  
Author(s):  
D.N. Hill-Manning ◽  
R.S. Blanquet
Keyword(s):  
Lipid Biosynthesis ◽  
Sea Anemones ◽  
Metridium Senile

Biochemical Genetic Variation, Growth and Regeneration of the Sea Anemone, Metridium, of British Shores

1985 ◽  
Vol 65 (1) ◽  
pp. 141-157 ◽  
Author(s):  
Ann Bucklin
Keyword(s):  
Genetic Differentiation ◽  
Taxonomic Status ◽  
Sea Anemone ◽  
Sea Anemones ◽  
The United Kingdom ◽  
Metridium Senile ◽  
Genetic Differentiation Of Populations ◽  
Biochemical Genetic ◽  
Enormous Number ◽  
Interesting System

Sessile organisms capable of asexual reproduction may be expected to show much genetic differentiation among local populations: mating between distant individuals is unlikely and genetic drift will contribute to differentiation since habitats can be colonized by one or a few individuals. This study investigates genetic differentiation of populations of the sea anemone Metridium senile (L.) in Great Britain. Individuals of M. senile are sessile and reproduce both sexually, by free-spawning of gametes, and asexually, by regeneration of fragments torn from the pedal disc. Metridium senile is one of the most common and widespread of British sea anemones (Manuel, 1981); reports place it at an enormous number and variety of sites around Britian (unpublished results of surveys by the Underwater Conservation Society of the United Kingdom). The extensive geographic range and variability of the species have confounded attempts to determine the taxonomic status of the ecological and morphological forms, but make it an interesting system for genetic analysis.

Facilitation in Sea Anemones

1945 ◽  
Vol 22 (1-2) ◽  
pp. 32-36
Author(s):  
D. M. ROSS
Keyword(s):  
Neuromuscular Transmission ◽  
Muscular Contraction ◽  
Single Stimulus ◽  
Sea Anemones ◽  
Metridium Senile ◽  
Neuromuscular Response ◽  
Calliactis Parasitica ◽  
Sensitizing Effect

1. Extracts of the sea anemones, Calliactis parasitica and Metridium senile, have been prepared and their effects on the neuromuscular response of these anemones tested. The presence of extract sensitizes the organism so that a response is given to a single stimulus, whereas normally this occurs only on the second and subsequent stimuli. No other significant effects were observed. 2. The sensitizing effect of the extract differs from the effect of a sensitizing drug like tyramine; it appears more quickly, more regularly, and it is rarely accompanied by an increase in the size of the muscular contraction. 3. The fact that a substance with sensitizing properties has been detected in anemones supports the view that a ‘sensitizer’ or ‘facilitator’ exists and takes part in neuromuscular transmission in these animals. Nevertheless, the extract, like the sensitizing drugs, lacks some of the properties that would be expected of a true ‘sensitizer’ or ‘facilitator’.

An Adrenergic Nervous System in Sea Anemones

1963 ◽  
Vol s3-104 (68) ◽  
pp. 531-534
Author(s):  
ERIK DAHL ◽  
BENGT FALCK ◽  
CLAES VON MECKLENBURG ◽  
HARRY MYHRBERG
Keyword(s):  
Nervous System ◽  
Fluorescence Microscopy ◽  
Motor Function ◽  
New Method ◽  
Sea Anemones ◽  
Fluorescent Substance ◽  
Metridium Senile ◽  
Adrenergic Nervous System ◽  
Oral Disk

A new method for the demonstration of certain mono-amines by means of fluorescence microscopy was applied to the tentacles and oral disk of the sea anemones Metridium senile and Tealia felina. A fluorescent substance was found in the cells and fibres of the tentacular ectodermal nervous system. This nervous system probably has a double sensory and motor function.

A Comparison of the Nervous Systems of two Sea-Anemones, Calliactis parasitica and Metridium senile

1961 ◽  
Vol s3-102 (59) ◽  
pp. 319-326
Author(s):  
ELAINE A. ROBSON
Keyword(s):  
Methylene Blue ◽  
Nervous System ◽  
Conduction System ◽  
Nerve Cells ◽  
Bipolar Cells ◽  
Retractor Muscle ◽  
Sea Anemones ◽  
Nerve Net ◽  
Metridium Senile ◽  
Calliactis Parasitica

The properties of the actinian nervous system are known mainly from physiological experiments on Calliactis parasitica (Couch), and from histological work on Metridium senile (L.). The structure of the nerve-net in the mesenteries of Calliactis is now shown to resemble in general that in Metridium. Methylene blue stains a network of bipolar cells over the retractor muscle, together with sense-cells, and unlike Metridium, multipolar nerve-cells. The nerve-net over the radial surface of the mesentery is similarly much sparser. The distribution of nerve-cells and sense-cells in the column also resembles that in Metridium. Experiments on Metridium show that as in Calliactis, the rate of conduction in the mesenteries is greater than in other parts of the anemone. The column, including the sphincter region, conducts more slowly. It is thus shown that the presence of a well developed nerve-net over the retractors is associated with the development of fast tracts in the through-conduction system, and of rapid, facilitated contractions of the retractor muscles, in both species of anemone.

Effects of Sea Anemones on the Flow Forces They Encounter

1977 ◽  
Vol 69 (1) ◽  
pp. 87-105 ◽  
Author(s):  
M.A. R. KOEHL
Keyword(s):  
Drag Force ◽  
Mechanical Forces ◽  
Flowing Water ◽  
Sea Anemones ◽  
Water Currents ◽  
Mechanical Responses ◽  
Drag Forces ◽  
Metridium Senile ◽  
Anthopleura Xanthogrammica ◽  
Sessile Organisms

Two species of sea anemones, Metridium senile and Anthopleura xanthogrammica, illustrate the sorts of compromises made by sessile organisms between maximizing the transport done and minimizing the mechanical forces caused by flow. 1.M. senile occur in calm areas, but because they are tall, they are exposed to mainstream current velocities. Although A. xanthogrammica occur in areas exposed to wave action, they are short and effectively hidden from mainstream velocities.2. Measurements of drag forces on anemones and models in a flow tank and in the field indicate that the shapes, sizes, flexibilities, and behaviours of anemones affect the flow forces they encounter.3. Although M. senile and A. xanthogrammica occur in different flow habitats, the drag force on an individual of either species is about 1 N.4. The water currents encountered by these anemones and their mechanical responses to the currents can be related to the manner in which the anemones harvest food from flowing water.

A Respiratory Rhythm in Sea Anemones

1977 ◽  
Vol 68 (1) ◽  
pp. 187-198
Author(s):  
W. C. JONES ◽  
VERONICA J. PICKTHALL ◽  
S. P. NESBITT
Keyword(s):  
Electrical Stimulation ◽  
Sea Water ◽  
Respiratory Rhythm ◽  
Continuous Recording ◽  
Average Period ◽  
Sea Anemones ◽  
Metridium Senile ◽  
Depletion Rate

Continuous recording of the O2 content of sea water containing an Actinia equina or a Metridium senile has revealed the occurrence of periodic deflexions on most of the records obtained. The deflexions are probably caused by the release of coelenteric fluid via the mouth. The average period of the rhythm varied from 24 to 43 min (14–15 °C). The period increased in darkness, but was unaffected by feeding, brief mechanical or electrical stimulation, longitudinal bisection of the column and excess KCl or MgCl2; 1.6 mMKCN abolished the rhythm. The O2 depletion rate did not increase when the anemone contracted in response to stimulation, but it did after feeding, exposure to darkness, or the application of MgCl2. It decreased in the presence of excess KCl. These changes may result from alterations in shape of the anemone. The mechanism for the release of coelenteric fluid has yet to be elucidated. Calculations indicate that from ½ to 1/9 of the total O2 requirement may enter the tissues from the coelenteron, the remainder being taken up via the ectoderm.

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