Biomineralization: Sponge Spicules and Skeletons

Description

This lecture explores the biomineralization process in sponges, focusing on the diversity of spicules and the structural organization of their skeletons. It covers the classification of sponges, the composition of spicules (silica and calcium carbonate), the role of organic fibers like spongin, and the genetic determination of spicule shapes. The lecture also delves into the intricate process of spiculogenesis, the localization of spicules, and the unique properties of sponge skeletons. Additionally, it discusses the hypercalcified sponges, their massive basal skeletons, and the potential environmental archive they provide. The study of elemental and isotopic ratios in sponge skeletons offers insights into paleotemperatures and changes in oceanic calcium concentrations.

Official source

https://mediaspace.epfl.ch/media/0_7mq9dkqd

About this result

This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.

Related lectures (12)

Related concepts (73)

Stable isotope ratio

The term stable isotope has a meaning similar to stable nuclide, but is preferably used when speaking of nuclides of a specific element. Hence, the plural form stable isotopes usually refers to isotopes of the same element. The relative abundance of such stable isotopes can be measured experimentally (isotope analysis), yielding an isotope ratio that can be used as a research tool. Theoretically, such stable isotopes could include the radiogenic daughter products of radioactive decay, used in radiometric dating.

Sponge spicule

Spicules are structural elements found in most sponges. The meshing of many spicules serves as the sponge's skeleton and thus it provides structural support and potentially defense against predators. Sponge spicules are made of calcium carbonate or silica. Large spicules visible to the naked eye are referred to as megascleres, while smaller, microscopic ones are termed microscleres. The composition, size, and shape of spicules are major characters in sponge systematics and taxonomy.

Sponge

Sponges, the members of the phylum Porifera (pəˈrɪfərə; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through them, consisting of jelly-like mesohyl sandwiched between two thin layers of cells. Sponges have unspecialized cells that can transform into other types and that often migrate between the main cell layers and the mesohyl in the process.

Isotopic signature

An isotopic signature (also isotopic fingerprint) is a ratio of non-radiogenic 'stable isotopes', stable radiogenic isotopes, or unstable radioactive isotopes of particular elements in an investigated material. The ratios of isotopes in a sample material are measured by isotope-ratio mass spectrometry against an isotopic reference material. This process is called isotope analysis. The atomic mass of different isotopes affect their chemical kinetic behavior, leading to natural isotope separation processes.

Isotopic labeling

Isotopic labeling (or isotopic labelling) is a technique used to track the passage of an isotope (an atom with a detectable variation in neutron count) through a reaction, metabolic pathway, or cell. The reactant is 'labeled' by replacing specific atoms by their isotope. The reactant is then allowed to undergo the reaction. The position of the isotopes in the products is measured to determine the sequence the isotopic atom followed in the reaction or the cell's metabolic pathway.