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Russians studies deep-sea glass sponges and asteroids

Hertwigia15 different species of glass sponges was collected from the Charlie Gibbs Fracture Zone. They have now been examined of the Russian expert in this field, Konstantin Tabachnick, together with Allen Collins from USA – and they suspect at least two of the species to be new.

By Allen Collins

During February 2005, Konstantin Tabachnick and Anna Dilman (Institute of Oceanology, Academy of Sciences, Moscow) traveled to the Bergen Museum to work with the invertebrate collections curated by Endre Willassen and Jon Kongsrud.

Konstantin TabachnickKonstantin is one of the world’s few experts in the group known as glass sponges or hexactinellids, many of which are conspicuous members of deep-sea benthic communities. Assisting Konstantin was Allen Collins (NMFS National Systematics Laboratory, Washington, DC), who at the same time received a crash course in hexactinellid spicules and taxonomy.

Among the glass sponges collected from the Charlie Gibbs Fracture Zone are more than 15 different species, at least two of which are suspected to be new. One specimen represents just the second occurrence of the genus Doconesthes. The distributions of several other hexactinellid genera are expanded by the specimens.

Moreover, one specimen revealed the body form of a species that had previously been known only from fragments. It turns out that Hertwigia falcifera, which was thought to be a branching form, has a tubular from with convoluted and branching walls (see Figure). This specimen is particularly exciting because it had attached to it numerous juvenile glass sponges, which are relatively rare in collections.

Asteroids in the deep sea?

Anna DilmanAsteroids, otherwise known as starfishes or seastars, are also well represented among the animals living in the Charlie Gibbs Fracture Zone. In fact, Anna Dilman’s preliminary assessment is that more than 30 species in 23 genera have been collected from this region of the deep sea floor. Among the specimens, are some rare finds. For example, Anna has identified representatives of the genus Myxaster, a genus previously known only from a small number of specimens.

Although none of the new samples from the Charlie Gibbs Fracture Zone appear to be previously undescribed species of asteroid, the new material widens the distributions of the species represented.

Dilman, Tabachnik and Collins' stay in Bergen was funded by the Norwegian Ministry of Foreign Affairs and NOAA.


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