title used in learnabout sections of A SNAIL'S ODYSSEY
  Predators & defenses
   
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Research study 1
 

photograph of a cluster of tubeworms Eudistylia vancouveri with a rockfish sheltering amongst themThe main predators of larval tubeworms are filter-feeding invertebrates (including tubeworms themselves) and filter-feeding fishes.  Like in most marine invertebrates, defenses appear to be mostly lacking in the larvae, but may include barbed setae on the trochophore larvae of some species (see Research Study 2 below). 

The main predators of adult tubeworms are likely to be fishes and possibly crabs that bite off the heads and tentacle crowns of feeding worms. Other than the protection offered by the tough nature of the tube, the chief defense photograph of a sunflower star Pycnopodia helianthoides apparently attacking a cluster of tubeworms Eudistylia vancouveriof tubeworms seems to be withdrawal.

This "predator", a juvenile rockfish Sebastodes sp.,
seems to be using a cluster of sabellids Eudistylia
vancouveri
for its own protection 0.5X





A sunflower star Pycnopodia helianthoides attacks
a cluster of tubeworms Eudistylia vancouveri. Judging
by how far the worms are able to withdraw into their
tubes, the attack is likely to be unsuccessful 0.4X

 
photograph of a green anemone Anthopleura xanthogrammica in a tidepool eating a cluster of tubeworms Eudistylia vancouveri courtesy Dave Cowles, Walla Walla University, Washington This unusual photo shows a green anemone Anthopleura
xanthogrammica
engulfing a cluster of tubeworms Eudistylia
vancouveri
. For now, at least, the worms seem unaffected by
their circumstances. Photograph courtesy Dave Cowles,
Walla Walla University rosario.wallawalla.edu.
 
 
photograph of a tubeworm Eudistylia vancouveri withdrawing taken from a video

CLICK HERE to see a video of 2 tubeworms Eudistylia vancouveri withdrawing, the first as a response to shadow/movement, and the second to touch.

NOTE the video replays automatically

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Research study 2
 

photographs of various trochophore larvae of tubewormsThe trochophore larva of the worm Sabellaria cementarium has an array of barbed setae that can be erected when disturbed (see photos).  Because the setae are lost during metamorphosis they are assumed to be adaptations to pelagic existence.  Experiments at Friday Harbor Laboratories, Washington show that when the setae appear in development the larvae appear to suffer less predation by ctenophores (sea marbles), megalops (advanced crab larvae), fishes, and hydroid and jellyfish medusae.  The setae may act to increase the apparent size of the larva to predators, or form a “buffer” zone around the larva (a predator gets stuck by the barbs and stays a certain distance away), or to irritate the mouthparts of a predator.  However, the barbed setae seem ineffective against being eaten by tunicates and sea mussels.  Pennington & Chia 1984 Biol Bull 167: 168.

 
Research study 3
 

photograph of dense settlement of spirorbis tubewormsVariation in recruitment of a sessile species, such as a tubeworm, results from events during planktonic life, choices made by the larvae during settling, and mortality of the juveniles after settlement.  Studies on settlement and survival of spirorbid polychaetes, Spirorbis eximus, on clay tiles beneath kelp-bed canopies in Santa Catalina Islands, California show that the spirorbids do not prefer to settle in potentially protective microhabitats such as pits in the substratum surface. However, predatory fishes, such as garibaldi, surf perches, and wrasses, do not seem to prey on the spirorbids, perhaps owing to the worms’ protective calcareous tubes.  As part of the same study, the authors note that larvae of the bryozoan Celleporaria brunnea tend to actively seek out the pits in which to settle, and in so doing suffer less predation from fishes.  Thus, in both instances, predation by fishes has relatively little effect on the spatial distribution or abundance of the populations, but for different reasons. Keough & Downes 1982 Oecologia 54: 348.

NOTE  the tiles are 15 x 15cm, each with twenty 5 x 5mm holes drilled into the surface to provide protective microhabitat


Dense growth of a sabellid
polychaete Spirorbis sp. 2X

 
Research study 4
 

photograph of a serpulid tubeworm Serpula columbianaSerpulids Serpula columbiana inhabit strongly calcified tubes and are protected when withdrawn by a similarly calcified/rubbery operculum which pops into place as the worm pulls into its tube.  During early development the operculum is derived from a modified tentacle. One notable feature of the opercular plate is that it is always clean.  Studies on a related serpulid species in Ireland, Serpula vermicularis, show that mucus is secreted across the cuticle of the operculum.  The authors suggest that the continual sloughing off of the mucus possibly combined an antibiotic factor in the mucus combine to keep the operculum clean.  Thorp et al. 1991 Bull Mar Sci 48: 412.

 

 

 

Serpula columbiana showing tentacular
structure and protective operculum 2X

 
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