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Hermit crab fur
Sponge & Cnidarian
Hermit crab fur
Hydractinia polyclina L. Agassiz, 1860
WoRMS AphialID
117644
Sample IDs
HMSC174-02832 https://bench.boldsystems.org/index.php/MAS_DataRetrieval_OpenSpecimen?selectedrecordid=ATCCN246-25; Quoddy 369 https://bench.boldsystems.org/index.php/MAS_DataRetrieval_OpenSpecimen?selectedrecordid=ATCCN287-25
Collected
Bay of Fundy (Passamaquoddy Bay)
Distinguishing Features
• This hydroid forms a fuzzy mat about three millimetres thick on shells occupied by hermit crabs.
• Three types of polyps rise from the mat (feeding polyps, reproductive polyps, and stinging polyps).
• Polyps are pink in colour and can be up to five millimetres high.
Habitat
Usually found on the shells of hermit crabs. However, occasionally found on the underside of rocks.
Geographic Range
This species was described from Grand Manan in the Bay of Fundy and has been found from the Gulf of St. Lawrence to Maine. Forms a sibling species group with the European species Hydractinia echinata and the more southerly northern American species Hydractinia symbiolongicarpus.
Fun Fact
This hydroid gets lots of benefits from living on a hermit crab's shell. Hydroids cannot move by themselves and by living on the back of a crab they have some chance of escaping from their sea slug predators. They also get access to more food. While the crab walks about it drags its shell over the seabed. Then the hydroid's feeding polyps can collect the tiny animals that live in the sediment. Hermit crabs also gather sometimes which allows the hydroids on their backs to get close enough to mate.
Barcode Distribution
BIN contains specimens of H. echinata from Sweden, Norway, and the Netherlands in Europe.
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