Marine Invertebrates I


Diversity, zoogeography, phylogeny and evolutionary ecology of the Porifera (sponges)

Sponges belong to the most abundant sessile marine animals and contribute significantly to the total biomass on the sea floor.  As active suspension feeders sponges play an important role for the benthic-pelagic  coupling processes within the marine food web . Furthermore, they structure the ocean floor and act as hosts for numerous other animals and microbes. Thus, the evolutionary radiation of the Porifera is a key to the diversity and distribution of marine benthic communities.

In our research we use an integrated approach of morphological and molecular techniques combined with palaeontological data to achieve a new understanding on the evolution of the Porifera and their ecological history and their numerous roles within the marine biotopes.

Sponges are known as important providers of natural products for medical and other purposes, especially Spongia officinalis, the bath sponge, is known and used  in human medicine  since millenniums.  To defend themselves against competitors and predators sponges have developed a very efficient chemical warfare by  producing bioactive substances, which are used also for human purposes.  In the pharma industry (among others),  bioactive  compounds from key-species of sponges play an increasing role. For the identification of these key species and the knowledge of their distribution and ecology, our expertise in taxonomy and biodiversity  research is needed.


Current projects

Taxomomy, diversity and ecology of selected key-species of Antarctic sponges

Taxonomy of Cladorhizidae und Latrunculiidae (Porifera: Demospongiae) in the Antarctic Ocean

The deep Southern Ocean hosts a highly diverse animal fauna, including many sponge species still unknown to science.  As part of our Antarctic research projects, we are working on their documentation and publication. The sponge family Cladorhizidae (carnivore sponges) is widely distributed in the deep oceans, and they are found to be the deepest sponge occcurrences World-wide. However, in the cold environment of the Antarctic continental shelf these sponges thrive in shallower depths of a few hundred meters, and here we also find many species new to science.

Species of the family Latrunculiidae, particularly Latrunculia, are known as promising producers of bioactive compounds, efficient against cancer and other diseases. Such chemical agents are now increasingly discovered within Antarctic sponges. However, the diagnosis and definitions of Southern Polar Latrunculia  species are largely inconsistent and unresolved, therefore this family is in urgent need of taxonomic revision. This is currently in progress by means of morphological comparisons combined with molecular research.

Carnivor sponge Abyssocladia  from the Antarctic deep-sea
Spicules  of  Latrunculia bocagei, SEM photo

Revision of the Antarctic Rosselliidae (Porifera: Hexactinellida)

Sponge communities on the Antarctic continental shelf currently represent the most extensive sponge grounds inthe World. These ecosystems harbour sponges from all four classes but the Demospongiae and Hexactinellida are byfar the most spectacular, abundant and diverse members of the Southern Ocean benthos. Two hexactinellid generaendemic to the Southern Ocean, Rossella spp. and Anoxycalyx (Scolymastra) joubini, which locally dominate andaccount for a large portion of the benthic biomass, are of special importance due to their ecological function as bio-constructors. They structure the sea floor, harbor vast invertebrate communities and act as pioneers in the settlement of former ice-shelves after their disintegration due to melting and breaking up of large ice areas, e. g. at theAntarctic Peninsula.  However, the species identification within the Antarctic Rosselliidae is severely hampered by the outdated taxonomy, the species definitions being contradictory and vague, probably due to an ongoing speciation process of these Hexactinellida. We are working on an integrated systematic taxonomy useful also for monitoring of the Antarctic to better understand the ecological implications of Global warming in the Southern Ocean.

Marine Evertebraten I
Antarctic glass sponge, Rossella levis

Deep-sea Porifera: Diversity, zoogeography and evolutionary ecology

Diversity of sponges in manganese nodule biotopes of the Clarion-Clipperton-Zone (NE Pacific)

The Clarion-Clipperton Fracture Zone (CCFZ) in the equatorial northeastern Pacific is the world’s largest potential deep-sea mining area for polymetallic nodules, also known as manganese nodules.  The total area comprises approximately 5.2 million km². In this region the glass sponges (Porifera, Hexactinellida) belong to the main taxa of benthic animals , and many of the discovered species are new to science. Based on new collections, taxonomic data and underwater video surveying we analyze the ecological  implications which can be expected from the planned deep-sea mining in this region.

Marine Evertebraten I
Glass sponge on manganese nodule in the Clarion-Clipperton Zone

Diversity of abyssal and bathyal sponges of the Kurile-Kamchatka Basin (NW Pazifik)

The Kurile-Kamchatka Basin with ist maximal depth  of  9700 m  is one of the Earth`s  deepest marine biotopes  and harbours numerous abyssal and bathyal animals which are so far are almost unknown. These organisms were observed and collected within the German-Russian KuramBio II Expedition (Kuril Kamchatka Biodiversity Studies II with RV Sonne). They are partly published but many taxa are still under study.  Currently, we investigate a highly diverse Porifera fauna from this expedition. Among the deepest findings of sponges World-wide are Demospongiae of the family Cladorhizidae (carnivore sponges). We also find many new species of glass sponges in this fauna.

The early evolution of Porifera

Porifera (sponges) probably represent the oldest stem of animals still living on Earth. Their  fossil record can be traced back to Late Precambrian, and  their evolutionary history is probably much longer.

Exceptionally preserved sponges of the Early Palaeozoic Anji Biota (Ordovician, Zhejiang Province, South China)

The Anji Biota of Zhejiang Province, South China, is an exceptionally preserved, sponge-dominated fauna from the latest Ordovician. It contains more than 100 sponge species, mainly glass sponges new to science, which probably thrived in a deep-water environment. Many of these sponges show striking similarities to extant sponge orders and families and allow important conclusions about the early evolution of these animals.

Marine Evertebraten I
Dorte Janussen during field work in China

Oldest sponge fossils in Earth´s history from the Late Precambrian Kushk Series, Central-Iran

The late Ediacaran deep-water marine shale deposits of the Kushk Series in Central Iran host a diverse assemblage of fossils, including terminal-Ediacaran index fossils that confirm a latest Ediacaran age (Nama-Assemblage ~545-539 Ma) for these deposits. The detected new sponge fossils confirm their presence in late Ediacaran and just before the Cambrian Explosion as the earliest animals in Earth history.

Important earlier projects, in collections of which research is still ongoing

Diversity and Phylogeny of key-taxa of Antarctic Porifera (DFG: JA 1063/14). Antarctic deep-sea expeditions ANDEEP I- III and SYSTCO I, II (2001-2012) with RV POLARSTERN

Dynamics and populations ecology of sponges at the former ice-shelves, Larsen AB, and surrounding areas, East og the Antarctic Peninsula (DFG: JA 1063/17-1). Antarktis-Expeditions ANT XXIII-8, BENDEX, LASSO, FROSN (2007-2015) with RV POLARSTERN