Dive 03: Who Will Back Off First?
Video courtesy of the NOAA Office of Ocean Exploration and Research, Windows to the Deep 2018. Download larger version (mp4, 20.0 MB).

Here comes a deepwater hermit crab (family Parapaguridae). Notice the very long legs with their elongate last segments – an adaption for moving across soft mud. Only the first two pair of walking legs actually serve in movement. The other two pair hang on to the covering of the soft abdomen.

In some species of parapagurids, a small hermit crab moves into a real gastropod shell. Later, an anemone (or in this case, a relative of sea anemones called a zoanthid) overgrows the shell and forms a snug shell-shaped covering. This "false shell" can sting and protect the crab from octopuses.

If the Deep Discoverer remotely operated vehicle stirred up the seafloor, the hermit crab may sense uncovered "goodies" such as worms or small clams and may be rushing over to snatch a meal.

Text contributed by Mary Wicksten, Texas A&M University.

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