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Permanent link (DOI): https://doi.org/10.7939/R3RX93N3M

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Sponges as sensitive animals: sensory systems and energetics of filtration in demosponges Open Access

Descriptions

Other title
Subject/Keyword
Filter feeding
Primary cilia
Energy budgets
Porifera
Behaviour
Sensory systems
Type of item
Thesis
Degree grantor
University of Alberta
Author or creator
Ludeman, Danielle A
Supervisor and department
Leys, Sally P (Biological Sciences)
Examining committee member and department
Palmer, Rich (Biological Sciences)
Lewis, Mark (Mathematical and Biological Sciences)
Department
Department of Biological Sciences
Specialization
Ecology
Date accepted
2015-01-30T11:53:32Z
Graduation date
2015-06
Degree
Master of Science
Degree level
Master's
Abstract
Sponges (Porifera) are abundant in most marine and freshwater ecosystems, and as suspension feeders they play a crucial role in filtering the water column. Their active pumping enables them to filter up to 900 times their body volume of water per hour, recycling nutrients and coupling the benthic and pelagic communities. Despite the ecological importance of sponge filter feeding, little is known about how sponges control the water flow through their canal system or how much energy it costs to filter the water. Sponges lack conventional muscles and nervous tissue, yet respond to stimuli through coordinated behaviours. Here, I show the presence of non-motile cilia in the canal system of sponges and study their role as flow sensors. I demonstrate that molecules known to block cationic channels in sensory cilia in other organisms reduce or eliminate sponge behaviour. In addition, removal of the cilia using chloral hydrate eliminates sponge contractions, suggesting the cilia are flow sensors and involved in controlling water flow through the canal system. Sponges have long been considered textbook examples of animals that use current-induced flow. I show evidence that suggests some species of demosponge do not use current-induced flow; rather, they respond behaviourally to increased ambient currents by reducing their pumping volume. Using a morphometric model of the canal system, I also show that filter feeding may be more energetically costly than previously thought. Measurements of pumping volume and oxygen drawdown in five species of demosponges show that pumping rates are variable within and between species, with more oxygen consumed the greater the pumping volume. Together, these data suggest that sponges have a lot of control over the volume of water pumped, which may be an adaptation to reduce the energetic cost of filtration in times of high stress.
Language
English
DOI
doi:10.7939/R3RX93N3M
Rights
Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
Citation for previous publication
Ludeman, Danielle A., et al. "Evolutionary origins of sensation in metazoans: functional evidence for a new sensory organ in sponges." BMC evolutionary biology 14.1 (2014): 3.  http://www.biomedcentral.com/1471-2148/14/3?cmpid=newscred

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