As the AUV tracked above the bottom at a particularly dynamic area of the reef called Hydrographers Passage, about 200 km off the mainland, a vast sandy dune field supporting an extensive community of the luminescent, suspension feeding brittle stars
(relatives of sea stars) came into view for the first time.
Similarly, high-density aggregations of brittle stars
and brachiopods in boulder-cobble areas and fields of sea pens and sea urchins in sand and mud habitats also may provide space and structure for other organisms (e.
Barnacles, dog whelks, brittle stars
, sculpins and sea urchins.
Brilliant red brittle stars
decorated the reef, as did Christmas tree worms, sea cucumbers and lobsters.
(Echinodermata: Ophiuroidea) are a common component of marine communities and often make up a significant portion of the biomass.
With no light, severely cold water, and intense pressure, most creatures here are invertebrates (lacking a backbone), such as sea cucumbers, brittle stars
, and tiny squid.
Spiny brittle stars
, Channel Islands National Park off Santa Barbara Island.
Undamaged, older larvae of sea stars and brittle stars
(as well as other echinoderms) sometimes clone themselves.
Instead of healthy-looking brittle stars
draping the corals' branches, the scientists also noticed uncharacteristically white brittle stars
tightly coiled around the branches of the corals.
Antarctic clams, snails and brittle stars
, because of adaptation to their environment, have soft shells and have never had to fight shell-crushing predators.
They included dead crabs and brittle stars
- starfish like critters that are normally bright orange and tightly wrapped around coral.
They recorded numerous species, including lobsters, many types of crab, northern prawns, little cuttle, sea slugs, urchins, common starfish, brittle stars
, colourful anemones and various fish, including plaice, bib and the ferocious sounding but harmless long-spined sea scorpions.
Propelled by the fast-warming Southern Ocean, the invaders' return will hit hardest animals such as brittle stars
, which evolved within a food chain of little predation, says Richard Aronson, an ecologist at the Dauphin Island Sea Lab in Alabama.
The list of animals that play possum includes not only the Virginia opossum, of course, but also some 21 snake species and plenty of other creatures as different as bison on the prairies and brittle stars
in the oceans.
Other organisms higher in the food chain at the Antarctic site include clams and brittle stars
, which are closely related to starfish, says Ishman.