A description of the embryology, larval development, and feeding of the sea anemones Anthopleura elegantissima and A. xanthogrammica

1974 ◽  
Vol 52 (11) ◽  
pp. 1383-1388 ◽  
Author(s):  
Arthur E. Siebert Jr.
Keyword(s):  
Larval Development ◽  
Phylogenetic Significance ◽  
Sea Anemones ◽  
Apical Tuft ◽  
Anthopleura Elegantissima ◽  
Anthopleura Xanthogrammica

The embryology of Anthopleura elegantissima and Anthopleura xanthogrammica is described. Ova of A. elegantissima are 120–150 μm in diameter and brown, while those of A. xanthogrammica are 175–225 μm in diameter and purple. In both species, cleavage is complete and equal: endoderm formation is by emboly. The planulae of both species are similar in appearance and are 150–250 μm in length with an apical tuft 60–75 μm in length. Feeding of the planulae is discussed, as is the function and phylogenetic significance of the apical sensory tuft of the planula.

Laboratory Behaviour of Mosshead Sculpins Clinocottus Globiceps Toward Their Sea Anemone Prey

1996 ◽  
Vol 76 (3) ◽  
pp. 793-809 ◽  
Author(s):  
Ronald M. Yoshiyama ◽  
Ann L. Knowlton ◽  
Jill R. Welter ◽  
Stephanie Comfort ◽  
Billie Jo Hopka ◽  
...  
Keyword(s):  
Laboratory Experiments ◽  
The Other ◽  
Sea Anemones ◽  
Average Order ◽  
Body Contact ◽  
The North ◽  
Significant Difference ◽  
Different Types ◽  
Anthopleura Elegantissima ◽  
Anthopleura Xanthogrammica

Mosshead sculpins, Clinocottus globiceps, of the North American Pacific coast commonly feed upon sea anemones and in doing so make frequent body contact with the anemone tentacles. An attempt was made to determine if some sort of acclimation process, as seen in certain pomacentrid anemone fishes, is necessary for C. globiceps to engage in such repeated contacts. The laboratory experiments with C. globiceps and three species of anemones (Anthopleura xanthogrammica, A. elegantissima, Urticina crassicornis) revealed no obvious and consistent acclimatory behaviours by the fish toward anemones following a period of enforced isolation from anemones. Actions by C. globiceps toward anemones included frequent bites to tentacles, touches to tentacles without biting (whether intentional or not), and bites to the anemone's base or column. Tentacle bites occurred, on average, significantly earlier than tentacle touches in trials with Anthopleura elegantissima. There was no evidence that either tentacle bites or tentacle touches occurred earlier than the other in trials with A xanthogrammica and U. crassicornis. In paired trials where individualC. globiceps were tested first with A. xanthogrammica and then with U. crassicornis, the fish showed no significant difference in response to the two anemone species, either in the frequencies of different types of actions (bites or touches) or in the average order in which tentacle bites or tentacle touches occurred. Experiments were also conducted to compare the degree to which different sculpin species avoided contact with anemone (A. elegantissima) tentacles. Clinocottus globiceps seemed more tolerant of contact with tentacles than were the other sculpins, and only C. globiceps appeared intentionally to touch tentacles, sometimes leaning against or biting them.

Mechanical Organization of Cantileverlike Sessile Organisms: Sea Anemones

1977 ◽  
Vol 69 (1) ◽  
pp. 127-142
Author(s):  
M.A. R. KOEHL
Keyword(s):  
Elastic Modulus ◽  
Body Wall ◽  
Local Buckling ◽  
Beam Theory ◽  
Extension Rate ◽  
Flexural Stiffness ◽  
Sea Anemones ◽  
Order Of Magnitude ◽  
Anthopleura Xanthogrammica ◽  
Sessile Organisms

Engineering beam theory has been used to analyse the ways in which body shape and elastic modulus of two species of sea anemones affect their mechanical responses to flow. 1.Anthopleura xanthogrammica is exposed to wave action, but because it is short, wide, and thick-walled, maximum tensile stresses in its body walls due to flow forces are an order of magnitude lower than those in the tall, slim, thin-walled, calm-water sea anemone Metridium senile.2. The elastic modulus of M. senile body wall is more dependent on extension rate than is that of A. xanthogrammica. Because the extension rate of M. senile body wall in tidal currents is higher than that of A. xanthogrammica in wave surge, the moduli of walls from these species when exposed to such flow conditions are similar, between 0.1 and 0.3 MN.m−2.3. The flexural stiffness of M. senile is lowest in the upper column where the anemones bend in currents: this orients their filter-feeding oral discs normal to the currents. The flexural stiffness of A. xanthogrammica is one to two orders of magnitude higher than that of M. senile; A. xanthogrammica remain upright in wave surge and feed on mussels that fall on their oral discs.4. The deflexions of these anemones predicted using beam theory are consistent with those observed in nature.5. The critical stress to produce local buckling is an order of magnitude lower for M. senile than for A. xanthogrammica.6. Several general principles of the organization of cantilever-like sessile organisms are revealed by this study of sea anemones.

Larval development and metamorphosis of Sabellaria cementarium Moore, 1906 (Polychaeta: Sabellariidae)

1985 ◽  
Vol 63 (5) ◽  
pp. 1037-1049 ◽  
Author(s):  
Peter R. Smith ◽  
Fu-Shiang Chia
Keyword(s):  
Substrate Specificity ◽  
Larval Development ◽  
Thoracic Segment ◽  
Beach Sand ◽  
Larval Behavior ◽  
Caudal Appendage ◽  
Apical Tuft ◽  
Low Degree ◽  
Settlement And Metamorphosis ◽  
65 H

The development of the polychaete Sabellaria cementarium Moore, 1906 proceeds at 10–14 °C, as follows: 23 h, early trochophore with prototroch and apical tuft; 65 h, 1 pair of provisional setae; 3.5 days, feeding trochophore; 18 days, metatrochophore; 4 weeks, metatrochophore with tentacle buds; 5–6 weeks, nectochaeta competent to metamorphose; 6–8 weeks, settlement and metamorphosis. Larval behavior is described. Tube sand of adult sabellariids (S. cementarium, Phragmatopoma lapidosa, ldanthrysus ornamentatus) and beach sand induced metamorphosis. Larvae exhibit a low degree of substrate specificity in their settlement, but sand is essential. Metamorphosis involves a loss of provisional setae, anterior rotation of tentacles and opercular cirri, and reduction of episphere. Following these changes, the juvenile secretes a mucoid tube to which sand grains are attached. Metamorphosis is considered complete when the caudal appendage has formed; this occurs 7–10 days postsettlement. Juveniles were kept in the laboratory for 38 days. During this time, they develop three pairs of tentacles, lose all larval pigment, and form a second thoracic segment. Within the opercular crown, primary opercular paleae replace settling paleae.

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