title used in learnabout sections of A SNAIL'S ODYSSEY
  Growth & regeneration
   
 

drawing of tubeworm building its tube taken from a videoThere are only a few studies on growth, and none specifically on regeneration, of west-coast tubeworms.

Parchment-tube dwellers like Eudistylia spp. add to their tubes by directing a string of particle-laden mucus from rejection-tracts near the mouth to the tube rim. The mucus is sticky and carries inedible particles like sand and silt. The worm directs the mucous string to the free edge of the tube-rim, attaches it there, then rotates slowly around in its tube, adding additional layers of mucus/sand as it goes.

 
 
drawing of tubeworm making its tube taken from a video

CLICK HERE to see a video of a tubeworm Eudistylia constructing its tube from mucus bearing sediments and other inedible particles, diverted as a string by special head appendages from the mouth region to the tube rim. Video courtesy Cindy Young, University of British Columbia.

NOTE the video replays automatically

 
Research study 1
 

photograph of tubeworm Eudistylia polymorphaApart from the chitin and hardened protein in their jaws, polychaetes are generally thought to be soft-bodied.  However, studies on tubeworms Eudistylia polymorpha collected in Venice, California suggest that an endoskeletal cartilage is present, a finding that goes against the commonly held notions that only vertebrates have “true” cartilage, and that endoskeletal structures are found only in deuterostomes (members of which include chordates and echinoderms).  The cartilage in question occurs in the form of basal supporting structures for the feeding tentacles. The authors note that a similar type of cartilage is represented by the odontophore cartilage of the radular apparatus of gastropods.  Person & Mathews 1967 Biol Bull 132: 244.

NOTE  mammalian cartilage is made up of primarily of chondroitin sulphate, the primary constituents of which (galactosamine, glucosame, urionic acid, and so on) are matched closely in molecular concentrations in the acid mucopolysaccharide material identified here as Eudistylia cartilage (an exception is a slightly higher sulphate content in the latter material)

 
Research study 2
 

graph showing growth of the lecithotrophic form of the tubeworm Capitella sp. on different algae and seagrassThe spionid worm Capitella sp.1 has 2 developmental modes 2.  Some individuals are lecithotrophic; others, planktotrophic.  Culture of the 2 types at the Bamfield Marine Sciences Centre, British Columbia on different algal and seagrass diets3 shows that lecithotrophic developers (see graph on Left) grow somewhat slower than planktotrophic developers (see graph on Right). Best growth is on a diet of Ulva, but more eggs are produced on a diet of bull kelp Nereocystis luetkeana.  Of 294 sexually mature individuals produced in culture, 93% are planktotrophic and 7% are lecithotrophic.  Qian & Chia 1992 J Exp Mar Biol Ecol 157: 159; for information on growth rates of Capitella capitata and Polydora ligni on different concentrations of phytoplankton see Qian & Chia 1991 Bull Mar Sci 48: 477.

graph showing growth of the planktonic  form of the tubeworm Capitella sp. on different algae and seagrassNOTE1  for convenience the authors have combined individuals with the 2 developmental modes into a single group which they describe as Capitella sp.  Lecithotrophic developers come from large eggs (250-400µm diameter) that are incubated for 2wk in the worm's tube.  The juveniles emerge from the tube as “nectochaetes”, swim for a day, then settle.  Planktotrophic developers hatch from small eggs (125µm diameter) and spend 2-3wk swimming in the plankton before settling

NOTE2 this type of development is known as poecilogony and is found in other west-coast marine invertebrates: LEARN ABOUT SEA STARS: REPRODUCTION & DEVELOPMENT: PTERASTER and LEARN ABOUT NUDIBRANCHS & RELATIVES: REPRODUCTION: HATCHING & LARVAL LIFE: ALDERIA

NOTE3
  the plants are freeze-dried, then ground to a powder.  Diets include the green alga Ulva lactuca, the brown kelps Nereocystis luetkeana and Macrocystis integrifolia, and the seagrass Zostera marina

 
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