27. The Interpretation of the Embryonic and Post-larval Characters of certain Tetraxonid Sponges, with Observations on Post-larval Growth-stages in some Species
Article first published online: 21 AUG 2009
Proceedings of the Zoological Society of London
Volume 101, Issue 2, pages 511–525, June 1931
How to Cite
Burton, M. (1931), 27. The Interpretation of the Embryonic and Post-larval Characters of certain Tetraxonid Sponges, with Observations on Post-larval Growth-stages in some Species. Proceedings of the Zoological Society of London, 101: 511–525. doi: 10.1111/j.1096-3642.1931.tb01027.x
- Issue published online: 30 OCT 2009
- Article first published online: 21 AUG 2009
- Received February 16, 1931.
- 1In certain species of Tetraxonida the period of adult life may, in some cases, be subdivided into as many as three distinct growth stages, each characterized by some evident change in the form of the spicules, coupled with changes in the arrangement of the skeleton, or even with differences in the gross morphology.
- 2A tangential skeleton is a primitive character, and species in which this persists throughout adult life may be regarded as having undergone little specialization.
- 3Extrusion of spicules takes place either continuously or at definite periods in the life cycle. This has been assumed by previous authors, but without definite reason for so doing, and the proof now forthcoming enables us to explain the absence of particular categories of spicules from certain individuals of a species, the disorganization of the skeleton SO often seen, and the differences in the arrangement of the dermal skeleton in different individuals of the same species.
- 4In the identification of species not only must the normal fluctuating variations and those due to ecological, geographical, and environmental factors be considered, but also those due to age.
- 5The order in which different forms of spicules appear in the life cycle indicates the order of their appearance in the evolution of the species, anti probably, although this yet remains to be proved, when reduction of the skeleton takes place the last spicules to appear are the first to disappear.