Sujet
Hexactinellae
Légende
The hexactinellids, or glass sponges, are characterized by siliceous spicules consisting of six rays intersecting at right angles, much like a toy jack. Hexactinellids are widely viewed as an early branch within the Porifera because there are major differences between extant hexactinellids and other sponges. In particular, much of their tissues are syncitia, extensive regions of multinucleate cytoplasm. Some discrete cell types do exist, including archaeocytes. Furthermore, whereas other sponges possess the ability to contract, hexactinellids do not. Moreover, hexactinellids possess a unique system for rapidly conducting electrical impulses across their bodies, allowing them to react quickly to external stimuli. Ernst Heinrich Philipp August Haeckel (16 February 1834 – 9 August 1919) was a German biologist, naturalist, philosopher, physician, professor, marine biologist, and artist who discovered, described and named thousands of new species, mapped a genealogical tree relating all life forms, and coined many terms in biology..
Germany
Date
1904
Crédit
Photo12/Universal Images Group/Buyenlarge
Notre référence
UMG20B29_343
Model release
Non
Property release
Non
Licence
Droits gérés
Format disponible
31,3Mo (2,3Mo) / 22,9cm x 34,3cm / 2700 x 4050 (300dpi)