Related Experiment Video
Updated: Feb 4, 2026

Analyzing Gene Expression from Marine Microbial Communities using Environmental Transcriptomics
Published on: February 18, 2009
The aquiferous systems of three marine demospongiae
1Redpath Museum, McGill University, P.O. Box 6070, Montreal, Quebec, Canada.
Abstract:
The aquiferous systems of three common, coastal, marine Demospongiae, Halichondria panicea (Pallas), Haliclona permollis (Bowerbank) and Microciona Prolifera (Ellis and Solander), are analyzed by measurements of cross-sectional areas of conducting elements. The patterns in demosponges of extremely different organizational morphologies are found to be quantitatively similar. The porocyte nature of the ostia is established for all three species. Choanocyte chamber densities range from 1 to 1.8 × 107 chambers ml-1 with 57 to 95 choanocytes per chamber (means). Cross-sectional area of the intervillar space of the choanocyte collars is calculated to be 12 to 56 times the lateral surface area of the specimen. Velocities of water movement through specific elements of the aquiferous system are calculated from cross-sectional area data and measured oscular flow of Haliclona permollis. The calculated Reynolds numbers lie below the critical value and fluid flow is thus considered laminar throughout the aquiferous systems of these sponges.
Related Concept Videos
Comparative Excretory Systems
Second Order systems II
First Order Systems
When a first-order system is subjected to a unit-step input, its response is characterized by its transfer function. By applying the Laplace transform of the unit-step input to the transfer function, expanding the...
Second Order systems I
By reinterpreting the system, one can derive the closed-loop transfer function, which...
Thermodynamic Systems
Consider an example of tea boiling in a kettle. The...
Classification of Systems-I
Homogeneity dictates that if an input x(t) is multiplied by a constant c, the output y(t) is multiplied by the same constant. Mathematically, this is expressed as:

