The larvae of some nectochaetes have more elaborate setae. In this case, the larva was rolling up into a ball with setae pointing outward, perhaps for protection from perceived predators. Credits: Laurel Hiebert
Little Creatures of the Deep [Slide Show]
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Sentry: The autonomous underwater vehicle, Sentry (yellow), is lowered into the Atlantic Ocean off the U.S. East Coast. Credit: Andrew Billings, WHOI
SyPRID: Two deep-sea sampler filters (white) are removed from their protective housings (gray) after a successful dive. Credit: Michael Jukuba, WHOI
Mitraria: This larva of a polychaete (segmented) annelid worm swims using a ciliated band. A bundle of long protective bristles protects its posterior. The juvenile develops inside the larval body and eventually emerges through a drastic metamorphosis... Credit: Laurel Hiebert
Nectochaete 1: In this nectochaete larva of a polychaete annelid worm, each segment bears setae, or bristles. Credit: Laurel Hiebert
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Nectochaete 2: The larvae of some nectochaetes have more elaborate setae. In this case, the larva was rolling up into a ball with setae pointing outward, perhaps for protection from perceived predators... Credit: Laurel Hiebert
Cyprid: This larval form of a barnacle called cyprid is very mature. It has antennae and cement glands that enable it to walk around and attach to a rock or another suitable object. Credit: Laurel Hiebert
Glottidia: Both the larvae and adults of this inarticulate brachiopod group have two large valves (shells) that protect filter feeding–tentacles inside. The cilia-covered tentacles extend so the larva can swim... Credit: Kara Robbins
Veliger: This larva of a bivalve mollusk looks just like the adult. A double-ciliated lobe called the velum is tucked away in the shell. When extended, the velum resembles two wings and allows the larva to swim... Credit: Laurel Hiebert
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Planula: A planula is the zeppelin-shaped larval stage of some cnidarians, including sea anemones and corals. They rotate slowly as they swim, eventually developing tentacles on the trailing end and attaching to the seafloor with the leading end... Credit: Laurel Hiebert
Brittle Star Juvenile: This brittle star has just changed into a juvenile, perhaps while it was being collected. Credit: Laurel Hiebert
At more than 2,150 meters deep in the ocean, the water pressure is a crushing 220 kilograms per square centimeter. Oceanographers who have tried to snag samples of life in these pitch-black, frigid and high-pressure places have had to suck in water at high speed and try to filter out organisms, often damaging them in the process. But a team led by Duke University, the University of Oregon and the Woods Hole Oceanographic Institution last week snatched up the intact larvae of 16 different animals.
The scientists used a new sampler, called SyPRID, which was carried to great depths by an autonomous underwater vehicle named Sentry. For more than eight hours engineers steered the robot in a precise and slow pattern. The maneuvering itself marked an achievement by barely disturbing the water in front of the craft—a common complication that pushes the tiny larvae out of a vehicle’s path before an instrument can pull them in. The long, cylindrical sampler processed large volumes of water every hour, yet did it slowly enough to not harm the fragile creatures, which are only a few hundred microns across. The final trick, according to an e-mail from Carl Kaiser, the vehicle program manager at Woods Hole, “is getting most of the larvae down to a relatively still area where they are further protected from the moving water.”
Scientists are eager to have intact specimens of common and rare organisms from the very deep ocean, especially in the early larval stages of life, because the samples can explain a lot about marine food webs, the changing nature of ocean ecosystems and how methane seeping up from the seafloor may be affecting the chemistry of the sea.
Two images of Sentry and SyPRID and nine images of the beautiful larvae can be seen in the accompanying slide show (see link below). Captions are based on descriptions by Laurel Hiebert, a team member at the University of Oregon. The work was supported by the National Science Foundation.
This article was updated from the original version on July 31, 2015.