The Larsen Worms

We tend to think of Antarctica as an inhospitable place, suitable only for warm-bodied penguins, seals, and whales. Below the surface, however, the Antarctic Ocean is home to a surprising diversity of life. Today Dr. James Blake (2015) named three new species of bottom-dwelling, marine worms.

The Antarctic Peninsula. Photo by Serge Ouachée, licensed under CC BY-SA 3.0.

The Antarctic Peninsula. Photo by Serge Ouachée, licensed under CC BY-SA 3.0.

The worms belong to the family Scalibregmatidae, sometimes referred to as “maggot worms” — even though “true” maggots are not worms, but the larvae of insects. Instead the Antarctic species are segmented or annelid worms, distantly related to the more familiar earthworms and leeches.

Within the annelids, maggot worms belong to a hugely diverse group called the bristle worms (Polychaeta). Most bristle worms are marine, and they come in a massive array of shapes, sizes, and lifestyles. Some look like tiny, colorful Christmas trees. Others glow in the dark. There are more than 10,000 known species of bristle worms, with many more yet to be discovered.

A common Antarctic maggot worm (Scalibregma inflatum). © WoRMS Editorial Board, licensed under CC BY-NC-SA 4.0.

A common Antarctic maggot worm (Scalibregma inflatum). © WoRMS Editorial Board, licensed under CC BY-NC-SA 4.0.

Blake’s maggot worms are neither luminous nor Christmas-tree-shaped. They are long-bodied, with the characteristic hair-like side appendages that give bristle worms their name. All three live by burrowing in the loose, silty seabed, more than 300 meters (~1,000 feet) below the surface.

Life is hard at the bottom. There is no sunlight for algae to grow, and plankton is scarce. The animals that live there survive by scavenging on the bits of detritus and dead animals that find their way to the sea floor. The maggot worms share their habitat with other worms, clams, and sea pigs.

The new worms were originally collected as part of an expedition to study the geology and sea-floor life of the Antarctic Peninsula (Domack et al. 2001). Although new species were an added bonus, the expedition’s main goal was to asses changes in the environment after the Larsen A ice shelf fell apart in 1999 due to climate change.

Larsen A, B, and C together make up the Larsen Ice Shelf, one of the largest in Antarctica. Since the expedition, Larsen B has partially broken up and the rest is expected to follow by the end of the decade (Khazendar et al. 2015). Larsen C, the biggest of the three, is showing signs of weakening, and could just as easily destabilize and tumble, like its neighbors, into the sea (Borstad et al. 2013).

The Larsen Ice Shelf. Photo by Jim Ross (NASA), in public domain.

The Larsen Ice Shelf. Photo by Jim Ross (NASA), in public domain.

How will the loss of glaciers, and their collapse into the ocean, affect the area’s maggot worms? No research I could find has answered this question, which is not surprising. I confess it seems trivial compared to the more pressing question, how will it affect us? That is a question that has been answered many times over.

Cited:

Blake J.A. 2015. New species of Scalibregmatidae (Annelida, Polychaeta) from the East Antarctic Peninsula including a description of the ecology and post-larval development of species of Scalibregma and Oligobregma. Zootaxa 4033(1): 057-093.

Borstad C.P., E. Rignot, J. Mouginot, and M.P. Schodlok. 2013. Creep deformation and buttressing capacity of damaged ice shelves: theory and application to Larsen C ice shelf. The Cryosphere 7(6): 1931-1947.

Domack E.A., A. Leventer, R. Gilbert, S.K. Brachfeld, S. Isman, A. Cmaerlenghi, K. Gavahan, D. Carlson, and A. Barkoukis. 2001. Cruise reveals history of Holocene Larsen Ice Shelf. EOS, Transactions of the American Geophysical Union 82 (2): 13‒17.

Khazendar A., C.P. Borstad, B. Scheuchl, E. Rignot, and H. Seroussi. 2015. The evolving instability of the remnant Larsen B Ice Shelf and its tributary glaciers. Earth and Planetary Science Letters 419: 199-210.

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