Bryozoan Monticules: Excurrent Water Outlets?

Banta, William C.; McKinney, Frank; Zimmer, Russel L.

doi:10.1126/science.185.4153.783

Cited by 69 publications

(49 citation statements)

References 3 publications

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“…Chimney parameters for the wild colonies in this study fell within the previously described ranges for Membranipora (Banta et al 1974;Cook 1980;Lidgard 1980). Chimneys in flume colonies, however, were larger and spaced farther apart than were those in the wild colonies.…”

Section: Discussionmentioning

confidence: 72%

“…The canopy is punctuated at regular intervals by chimneys (Fig. lb), areas in which lo-741 743 phophores are modified to produce excurrent sites for deHowever, no empirical or theoretical study has yet examined pleted water (Banta et al 1974;Cook and Chimonides 1980; the underlying source(s) of the cost of inducible defense in Dick 1987).…”

Section: Acknowlulgmentsmentioning

confidence: 99%

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Hydromechanical mechanisms of colony organization and cost of hefense in an encrusting bryozoan, Membranipora membranacea

Grünbaum

1997

Limnology & Oceanography

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In bryozoans, hydrodynamic interactions among colony members can substantially affect filtering rates and access to food-rich water for zooids within a colony and for the colony as a whole. Hydrodynamic theory suggests that highly integrated (area-filling) colony architectures lead to strong interference bctwccn neighboring zooids, whereas less integrated architectures do not. The highly integrated bryozoan Membrunipora membranacea displays two morphological specializations that modify hydrodynamic interactions: internal excurrent zones (chimneys) and inducible defensive spines. In this study, possible hydrodynamic mechanisms underlying the cost of inducible defense and chimney organization were tested experimentally by culturing spined and unspined colonies under controlled flow conditions. Spines reduced colony growth rate when growth was limited by clearance rates, but not when transport of particles from upstream limited growth. This supports the hypothesis that the cost of inducible defense is primarily a reduction in clearance rate (i.e. spines cause hydrodynamic interference with feeding currents) rather than metabolic investment in spine construction. Chimneys were more closely spaced in spined than unspined colonies, consistent with a mechanism for organizing chimney formation based on responses by zooids to local hydromechanical cues rather than a rigid, colony-level control of zooid growth form (astogeny). Direct manipulation of hydrodynamic cues resulted in substantial changes in chimney morphology, again supporting the hydromechanical organization mechanism. More generally, these cxpcrimental results support the theoretical assessment that the highly integrated architecture is hydrodynamically unfavorable. The success of Membruniporu in some habitats suggests that its architecture confers compensating advantages, such as improved ability to compete for space. This tradeoff in growth habit may explain shifts in relative prevalence of bryozoan architectures with depth and across other environmental gradients.Bryozoans are a group of colonial suspension feeders for which there is strong evidence that flow patterns are important in determining feeding success. Bryozoan colonies consist of small modules (zooids), which feed by everting ciliated tentacular structures (lophophores) that induce water currents, from which food particles are extracted. Observations of flow rates through lophophores and particle capture rates of individual zooids have shown that the feeding success of zooids varies with extrinsic factors such as external flow speed (Cancino and Hughes 1987;Hughes and Hughes 1986; Okamura 1992) and food content (Best and Thorpe 1983, 1986a;Okamura 1987), the presence of neighboring con-and heterospecific colonies (Best and Thorpe 1986b;Okamura 1988), as well as with intrinsic colony characteristics such as colony growth form (Okamura 1984(Okamura , 1985 and the specialization of zooid morphologies (McKinney and I Present address:

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Section: Discussionmentioning

confidence: 72%

Section: Acknowlulgmentsmentioning

confidence: 99%

Hydromechanical mechanisms of colony organization and cost of hefense in an encrusting bryozoan, Membranipora membranacea

Grünbaum

1997

Limnology & Oceanography

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“…They may be important functional attributes, thought to affect water flow patterning by orienting zooid Nodes, and corresponding apomorphy changes at each, are listed in Table 4. lophophore orientation, and affecting feeding currents (Anstey 1981;Anstey 1986;Banta et al 1974;Taylor 1979). This result supports Astrova's (1965) …”

Section: Resultsmentioning

confidence: 99%

Cladistic analysis of the Paleozoic bryozoan families Monticuliporidae and Mesotrypidae

Adamczyk

Pachut

2013

J. Paleontol.

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A set of 127 binary and multistate characters, weighted by the number of derived character states, degree of covariation, and level of homoplasy, was used in a cladistic analysis of type species representing 12 genera previously assigned to families Monticuliporidae and Mesotrypidae. The most parsimonious tree consisted of a 10-genus monophyletic crown group with the remaining two genera forming a basal paraphyletic stem group. The composition of the monticuliporid crown group is broadly similar to two earlier classifications while stem group membership matches the family Mesotrypidae. Phenetic groupings, based on overall morphological similarity, have memberships that are similar to those of clades but provide no means of determining the polarity of evolutionary relationships either within or between them. Finally, only the observed stratigraphic ranges of the type species of genera provide a statistically significant match with cladistic branching sequence, perhaps because current composite generic ranges reflect the mixing of species belonging to different genera. Based on cladogram topology, we propose the placement of all 12 genera into a single family Monticuliporidae.

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“…In some species of bryozoans, chimneys are associated with bumps on the colony surface produced by growth of the zooecium (the box around the zooid) or by budding of zooids perpendicular to the colony surface (Banta et al, 1974;Cook, 1977;Ryland, 2001;Shunatova and Ostrovsky, 2002;Winston, 1978Winston, , 1979. Sometimes the chimneys are even associated with the position of male zooids (Ryland, 2001).…”

Section: Both Growth and Behavior Contribute To Chimney Morphologymentioning

confidence: 99%

“…Because chimneys function to let filtered water out of the colony (Banta et al, 1974;Lidgard, 1981) and to reduce recirculation of the filtered water (Eckman and Okamura, 1998), the correlation between flow and chimney formation may be advantageous for these colonies. Forming chimneys at sites of high excurrent flow at the canopy edge might insure that the excurrent stream out of the new chimney will be strong enough to push filtered water far from the colony, thereby reducing recirculation.…”

Section: Possible Implications For Performancementioning

confidence: 99%

Flow and conduit formation in the external fluid-transport system of a suspension feeder

Dassow

2005

Journal of Experimental Biology

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SUMMARY To what extent is the development of a fluid-transport system related to flow within the system? Colonies of the bryozoan Membranipora membranacea have a simple external fluid-transport system with three components: the canopy of lophophores (crowns of ciliated tentacles), the edge of the canopy, and chimneys (raised openings in the canopy). The lophophores pump seawater into the colony and capture food particles from the seawater. The chimneys and canopy edge let the water back out of the colony. New chimneys form at the canopy edge as the colony grows. I tested whether there was a correlation between chimney formation and excurrent flow speed at the canopy edge by measuring excurrent flow speeds prior to chimney formation. Excurrent flow speeds were higher in regions that produced chimneys than in regions that did not form chimneys. Observations of changes in chimney shape after anesthetization with MgCl2 suggest that both growth and behavior determine chimney shape. Together, the results suggest that there is a strong correlation between growth and flow in this external fluid-transport system, with new chimneys forming at sites of high flow.

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Bryozoan Monticules: Excurrent Water Outlets?

Abstract: Monticules, regularly arranged modified areas on Paleozoic Bryozoa, may represent regions from which water currents produced by lophophores of adjacent feeding zoids escaped. Such circulation Patterns have been observed Recent forms.

Cited by 69 publications

References 3 publications

Hydromechanical mechanisms of colony organization and cost of hefense in an encrusting bryozoan, Membranipora membranacea

Hydromechanical mechanisms of colony organization and cost of hefense in an encrusting bryozoan, Membranipora membranacea

Cladistic analysis of the Paleozoic bryozoan families Monticuliporidae and Mesotrypidae

Flow and conduit formation in the external fluid-transport system of a suspension feeder

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