Selective settlement by larvae of Membranipora membranacea and Electra pilosa (Ectoprocta) along kelp blades in Nova Scotia, Canada

SUMMARYFive cyphonautes are described in Nordisches Plankton (Lohmann, 1911). Cyphonautes schneideri and C. borealis are larvae of Membranipora membranacea and represent extremes of variation in the shape of the shell. Cyphonautes balticus, like C. compressus which was very inadequately described, is the larva of Electra pilosa. The cyphonautes of these two species are the only ones likely to be encountered in the plankton of normally saline European seas. Cyphonautes barroisi is the larva of the brackish-water Electra crustulenta.Cyphonautes balticus Thorson (1946), not Lohmann, is the larva of M. membranacea.Larval synonymies for M. membranacea and E. pilosa are given.The use of the Cyphonautes names is undesirable, and those of the polyzoan adults should be employed.

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Electrophysiology and Co-ordinated Behavioural Responses in the Colonial Bryozoan Membranipora Membranacea (L.)

Journal of Experimental Biology ◽

10.1242/jeb.62.2.389 ◽

1975 ◽

Vol 62 (2) ◽

pp. 389-404

Author(s):

J. P. THORPE ◽

G. A. B. SHELTON ◽

M. S. LAVERACK

Keyword(s):

Nervous System ◽

Conduction Velocity ◽

Giant Axon ◽

Nerve Plexus ◽

Retractor Muscle ◽

Contraction Rate ◽

Membranipora Membranacea ◽

Behavioural Responses ◽

Electra Pilosa

1. There is a colonial retraction response in the Bryozoans Membranipora membranacea and Electra pilosa. 2. The conduction velocity of the response is about 100 cm sec−1. 3. The colonial response will circumnavigate the end of a cut, but will not cross it. 4. The lophophore retraction time is 60–80 msec. 5. The lophophore retractor muscle with a peak contraction rate of 20 + muscle lengths per second is probably one of the fastest contracting muscles known. 6. The colonial responses to successive stimuli under certain circumstances are similar to those of some corals. 7. Nervous pulses can be recorded travelling across the colony at the same velocity as the colonial response. 8. Increases and decreases in the number and frequency of T1 pulses correspond with increases and decreases in the area and duration of the colonial response and are produced in response to the same stimuli. 9. Other pulses can be recorded which correspond to the retraction of the lophophore retractor muscle. 10. The lophophore retractor muscle is apparently under the control of a giant axon from the zooidal ganglion. 11. The colonial nervous system has many of the properties expected of a nerve plexus.

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The cyphonautes larvae of the Plymouth area and the metamorphosis of Membranipora membranacea (L.)

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315400008742 ◽

1955 ◽

Vol 34 (3) ◽

pp. 441-449 ◽

Cited By ~ 31

Author(s):

D. Atkins

Keyword(s):

Membranipora Membranacea ◽

Electra Pilosa ◽

Do So

Several cyphonautes larvae (Polyzoa Ectoprocta) have been distinguished and described (Lohmann, 1911; Marcus, 1940; Thorson, 1946), but few have been seen to metamorphose, thus Unking the late larva with the adult. Three, belonging to the suborder Cheilostomata, which have been observed to do so, are Cyphonautes compressus into Electra pilosa L. (Schneider, 1869; Barrois, 1877; Kupelwieser, 1905–6), Cyphonautes occidentalis into Membranipora villosa, (Robertson, 1908; O'Donoghue, 1927) and an unnamed cyphonautes into Nichtina ( = Membranipora) tuberculata (Hastings, 1929, pp. 706–7).

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Destructive grazing, epiphytism, and disease: the dynamics of sea urchin - kelp interactions in Nova Scotia

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f99-163 ◽

1999 ◽

Vol 56 (12) ◽

pp. 2300-2314 ◽

Cited By ~ 124

Author(s):

Robert E Scheibling ◽

Allan W Hennigar ◽

Toby Balch

Keyword(s):

Nova Scotia ◽

Sea Urchin ◽

Canopy Cover ◽

Strongylocentrotus Droebachiensis ◽

Exposed Site ◽

Membranipora Membranacea ◽

Kelp Beds ◽

Sheltered Site ◽

Kelp Canopy ◽

Over Time

We measured the rate of advance of urchin (Strongylocentrotus droebachiensis) feeding aggregations (fronts) as they destructively grazed kelp beds (Laminaria longicruris) at both a wave-exposed site and a sheltered site in Nova Scotia over 3.5 years. The grazing fronts were composed of high densities of large adults (up to 98 and 70 per 0.25 m2 at the exposed and sheltered sites, respectively). Urchins in the recently formed barrens, or in adjacent kelp beds, occurred at much lower densities and consisted mainly of juveniles. The fronts moved onshore into shallower water at each site, but their rate of advance varied markedly between sites and over time at each site, ranging from 0 to 4 m·month-1. The rate of advance of a front was related to the biomass of urchins; fronts did not advance below a threshold biomass of ~2 kg·m-2. Infestations of kelp by an epiphytic bryozoan (Membranipora membranacea) caused marked reductions in kelp canopy cover and biomass during winter, but the canopy regenerated through recruitment of juvenile sporophytes in spring. A localized outbreak of disease decimated S. droebachiensis at the exposed site in 1993, which enabled kelp to recolonize the barrens. Surviving urchins gradually reaggregated and resumed destructive grazing after ~1.5 years. A recurrence of disease in 1995 eliminated urchins at both sites and terminated the transition from kelp beds to barrens on a coastal scale. Our findings have important implications for the management of the urchin fishery, which targets grazing fronts for harvesting.

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