In 2007, following the sudden collapse of the Antarctic ice shelves Larsen A (1995) and Larsen B (2002), scientists had a unique opportunity to study the animal life in the previously unexplored habitat beneath the great tongues of ice and to observe how the fauna was changing as a result of the loss of ice. Their survey showed that before the collapse of the ice shelves the ocean currents carried so little food beneath the ice tongues that only a few suspension eaters such as the vase sponges Rossella nuda and Rossella racovitzae were able to exist under the ice. They occurred so sporadically and were so small in size that the researchers thought each animal reminiscent of a solitary tennis ball lying on a tennis court with the next sponge, metaphorically speaking, not on the same court but on an adjacent one.
However, the biologists were surprised to find 16 animal species from the deep Antarctic sea under the ice shelves; most of these were echinoderms such as the sea lilies Bathycrinus australis and Dumetocrinus antarcticus. As a result of this discovery the scientists concluded that living conditions under the shelf ice probably resembled those in the deep sea and it was this that had enabled the dwellers of the deep to migrate to the shelf-sea zone.
The collapse of the ice altered the supply of light and food in the water. Although the areas were and still are frequently covered by sea ice, algal blooms occurred from time to time. Other organic material was carried in by the currents, enabling pioneer species such as sea squirts and glass sponges to colonize the deserted areas. The vase sponges successfully reproduced and, attracted by the food supply, ice krill, Antarctic krill and Antarctic silverfish swam in the water column. This in turn drew in larger hunters. In the summer of 2007 the biologists found that there were roughly as many crabeater seals and dwarf whales in the former shelf-ice region as would normally occur elsewhere in the Weddell Sea or off the west coast of the Antarctic Peninsula. In other words, the fauna of the Weddell Sea was already reconquering the habitat that had been lost for so long.